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authorLinus Torvalds <torvalds@linux-foundation.org>2012-07-24 10:01:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-07-24 10:01:50 -0700
commit3c4cfadef6a1665d9cd02a543782d03d3e6740c6 (patch)
tree3df72faaacd494d5ac8c9668df4f529b1b5e4457 /Documentation
parente017507f37d5cb8b541df165a824958bc333bec3 (diff)
parent320f5ea0cedc08ef65d67e056bcb9d181386ef2c (diff)
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Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking changes from David S Miller: 1) Remove the ipv4 routing cache. Now lookups go directly into the FIB trie and use prebuilt routes cached there. No more garbage collection, no more rDOS attacks on the routing cache. Instead we now get predictable and consistent performance, no matter what the pattern of traffic we service. This has been almost 2 years in the making. Special thanks to Julian Anastasov, Eric Dumazet, Steffen Klassert, and others who have helped along the way. I'm sure that with a change of this magnitude there will be some kind of fallout, but such things ought the be simple to fix at this point. Luckily I'm not European so I'll be around all of August to fix things :-) The major stages of this work here are each fronted by a forced merge commit whose commit message contains a top-level description of the motivations and implementation issues. 2) Pre-demux of established ipv4 TCP sockets, saves a route demux on input. 3) TCP SYN/ACK performance tweaks from Eric Dumazet. 4) Add namespace support for netfilter L4 conntrack helpers, from Gao Feng. 5) Add config mechanism for Energy Efficient Ethernet to ethtool, from Yuval Mintz. 6) Remove quadratic behavior from /proc/net/unix, from Eric Dumazet. 7) Support for connection tracker helpers in userspace, from Pablo Neira Ayuso. 8) Allow userspace driven TX load balancing functions in TEAM driver, from Jiri Pirko. 9) Kill off NLMSG_PUT and RTA_PUT macros, more gross stuff with embedded gotos. 10) TCP Small Queues, essentially minimize the amount of TCP data queued up in the packet scheduler layer. Whereas the existing BQL (Byte Queue Limits) limits the pkt_sched --> netdevice queuing levels, this controls the TCP --> pkt_sched queueing levels. From Eric Dumazet. 11) Reduce the number of get_page/put_page ops done on SKB fragments, from Alexander Duyck. 12) Implement protection against blind resets in TCP (RFC 5961), from Eric Dumazet. 13) Support the client side of TCP Fast Open, basically the ability to send data in the SYN exchange, from Yuchung Cheng. Basically, the sender queues up data with a sendmsg() call using MSG_FASTOPEN, then they do the connect() which emits the queued up fastopen data. 14) Avoid all the problems we get into in TCP when timers or PMTU events hit a locked socket. The TCP Small Queues changes added a tcp_release_cb() that allows us to queue work up to the release_sock() caller, and that's what we use here too. From Eric Dumazet. 15) Zero copy on TX support for TUN driver, from Michael S. Tsirkin. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1870 commits) genetlink: define lockdep_genl_is_held() when CONFIG_LOCKDEP r8169: revert "add byte queue limit support". ipv4: Change rt->rt_iif encoding. net: Make skb->skb_iif always track skb->dev ipv4: Prepare for change of rt->rt_iif encoding. ipv4: Remove all RTCF_DIRECTSRC handliing. ipv4: Really ignore ICMP address requests/replies. decnet: Don't set RTCF_DIRECTSRC. net/ipv4/ip_vti.c: Fix __rcu warnings detected by sparse. ipv4: Remove redundant assignment rds: set correct msg_namelen openvswitch: potential NULL deref in sample() tcp: dont drop MTU reduction indications bnx2x: Add new 57840 device IDs tcp: avoid oops in tcp_metrics and reset tcpm_stamp niu: Change niu_rbr_fill() to use unlikely() to check niu_rbr_add_page() return value niu: Fix to check for dma mapping errors. net: Fix references to out-of-scope variables in put_cmsg_compat() net: ethernet: davinci_emac: add pm_runtime support net: ethernet: davinci_emac: Remove unnecessary #include ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/DocBook/80211.tmpl1
-rw-r--r--Documentation/connector/cn_test.c13
-rw-r--r--Documentation/devicetree/bindings/net/broadcom-bcm87xx.txt29
-rw-r--r--Documentation/devicetree/bindings/net/can/fsl-flexcan.txt3
-rw-r--r--Documentation/devicetree/bindings/net/davinci_emac.txt41
-rw-r--r--Documentation/devicetree/bindings/net/fsl-fec.txt6
-rw-r--r--Documentation/devicetree/bindings/net/phy.txt12
-rw-r--r--Documentation/devicetree/bindings/net/stmmac.txt3
-rw-r--r--Documentation/feature-removal-schedule.txt44
-rw-r--r--Documentation/networking/batman-adv.txt5
-rw-r--r--Documentation/networking/bonding.txt6
-rw-r--r--Documentation/networking/bridge.txt13
-rw-r--r--Documentation/networking/caif/Linux-CAIF.txt91
-rw-r--r--Documentation/networking/can.txt186
-rw-r--r--Documentation/networking/ip-sysctl.txt62
-rw-r--r--Documentation/networking/openvswitch.txt2
-rw-r--r--Documentation/networking/s2io.txt14
-rw-r--r--Documentation/networking/stmmac.txt36
-rw-r--r--Documentation/networking/vxge.txt7
-rw-r--r--Documentation/nfc/nfc-hci.txt33
20 files changed, 449 insertions, 158 deletions
diff --git a/Documentation/DocBook/80211.tmpl b/Documentation/DocBook/80211.tmpl
index f3e214f9e25..42e7f030cb1 100644
--- a/Documentation/DocBook/80211.tmpl
+++ b/Documentation/DocBook/80211.tmpl
@@ -404,7 +404,6 @@
!Finclude/net/mac80211.h ieee80211_get_tkip_p1k
!Finclude/net/mac80211.h ieee80211_get_tkip_p1k_iv
!Finclude/net/mac80211.h ieee80211_get_tkip_p2k
-!Finclude/net/mac80211.h ieee80211_key_removed
</chapter>
<chapter id="powersave">
diff --git a/Documentation/connector/cn_test.c b/Documentation/connector/cn_test.c
index 7764594778d..adcca0368d6 100644
--- a/Documentation/connector/cn_test.c
+++ b/Documentation/connector/cn_test.c
@@ -69,9 +69,13 @@ static int cn_test_want_notify(void)
return -ENOMEM;
}
- nlh = NLMSG_PUT(skb, 0, 0x123, NLMSG_DONE, size - sizeof(*nlh));
+ nlh = nlmsg_put(skb, 0, 0x123, NLMSG_DONE, size - sizeof(*nlh), 0);
+ if (!nlh) {
+ kfree_skb(skb);
+ return -EMSGSIZE;
+ }
- msg = (struct cn_msg *)NLMSG_DATA(nlh);
+ msg = nlmsg_data(nlh);
memset(msg, 0, size0);
@@ -117,11 +121,6 @@ static int cn_test_want_notify(void)
pr_info("request was sent: group=0x%x\n", ctl->group);
return 0;
-
-nlmsg_failure:
- pr_err("failed to send %u.%u\n", msg->seq, msg->ack);
- kfree_skb(skb);
- return -EINVAL;
}
#endif
diff --git a/Documentation/devicetree/bindings/net/broadcom-bcm87xx.txt b/Documentation/devicetree/bindings/net/broadcom-bcm87xx.txt
new file mode 100644
index 00000000000..7c86d5e28a0
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/broadcom-bcm87xx.txt
@@ -0,0 +1,29 @@
+The Broadcom BCM87XX devices are a family of 10G Ethernet PHYs. They
+have these bindings in addition to the standard PHY bindings.
+
+Compatible: Should contain "broadcom,bcm8706" or "broadcom,bcm8727" and
+ "ethernet-phy-ieee802.3-c45"
+
+Optional Properties:
+
+- broadcom,c45-reg-init : one of more sets of 4 cells. The first cell
+ is the MDIO Manageable Device (MMD) address, the second a register
+ address within the MMD, the third cell contains a mask to be ANDed
+ with the existing register value, and the fourth cell is ORed with
+ he result to yield the new register value. If the third cell has a
+ value of zero, no read of the existing value is performed.
+
+Example:
+
+ ethernet-phy@5 {
+ reg = <5>;
+ compatible = "broadcom,bcm8706", "ethernet-phy-ieee802.3-c45";
+ interrupt-parent = <&gpio>;
+ interrupts = <12 8>; /* Pin 12, active low */
+ /*
+ * Set PMD Digital Control Register for
+ * GPIO[1] Tx/Rx
+ * GPIO[0] R64 Sync Acquired
+ */
+ broadcom,c45-reg-init = <1 0xc808 0xff8f 0x70>;
+ };
diff --git a/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt b/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
index f31b686d455..8ff324eaa88 100644
--- a/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
+++ b/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt
@@ -11,6 +11,9 @@ Required properties:
- reg : Offset and length of the register set for this device
- interrupts : Interrupt tuple for this device
+
+Optional properties:
+
- clock-frequency : The oscillator frequency driving the flexcan device
Example:
diff --git a/Documentation/devicetree/bindings/net/davinci_emac.txt b/Documentation/devicetree/bindings/net/davinci_emac.txt
new file mode 100644
index 00000000000..48b259e29e8
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/davinci_emac.txt
@@ -0,0 +1,41 @@
+* Texas Instruments Davinci EMAC
+
+This file provides information, what the device node
+for the davinci_emac interface contains.
+
+Required properties:
+- compatible: "ti,davinci-dm6467-emac";
+- reg: Offset and length of the register set for the device
+- ti,davinci-ctrl-reg-offset: offset to control register
+- ti,davinci-ctrl-mod-reg-offset: offset to control module register
+- ti,davinci-ctrl-ram-offset: offset to control module ram
+- ti,davinci-ctrl-ram-size: size of control module ram
+- ti,davinci-rmii-en: use RMII
+- ti,davinci-no-bd-ram: has the emac controller BD RAM
+- phy-handle: Contains a phandle to an Ethernet PHY.
+ if not, davinci_emac driver defaults to 100/FULL
+- interrupts: interrupt mapping for the davinci emac interrupts sources:
+ 4 sources: <Receive Threshold Interrupt
+ Receive Interrupt
+ Transmit Interrupt
+ Miscellaneous Interrupt>
+
+Optional properties:
+- local-mac-address : 6 bytes, mac address
+
+Example (enbw_cmc board):
+ eth0: emac@1e20000 {
+ compatible = "ti,davinci-dm6467-emac";
+ reg = <0x220000 0x4000>;
+ ti,davinci-ctrl-reg-offset = <0x3000>;
+ ti,davinci-ctrl-mod-reg-offset = <0x2000>;
+ ti,davinci-ctrl-ram-offset = <0>;
+ ti,davinci-ctrl-ram-size = <0x2000>;
+ local-mac-address = [ 00 00 00 00 00 00 ];
+ interrupts = <33
+ 34
+ 35
+ 36
+ >;
+ interrupt-parent = <&intc>;
+ };
diff --git a/Documentation/devicetree/bindings/net/fsl-fec.txt b/Documentation/devicetree/bindings/net/fsl-fec.txt
index 4616fc28ee8..d5363922140 100644
--- a/Documentation/devicetree/bindings/net/fsl-fec.txt
+++ b/Documentation/devicetree/bindings/net/fsl-fec.txt
@@ -7,10 +7,14 @@ Required properties:
- phy-mode : String, operation mode of the PHY interface.
Supported values are: "mii", "gmii", "sgmii", "tbi", "rmii",
"rgmii", "rgmii-id", "rgmii-rxid", "rgmii-txid", "rtbi", "smii".
-- phy-reset-gpios : Should specify the gpio for phy reset
Optional properties:
- local-mac-address : 6 bytes, mac address
+- phy-reset-gpios : Should specify the gpio for phy reset
+- phy-reset-duration : Reset duration in milliseconds. Should present
+ only if property "phy-reset-gpios" is available. Missing the property
+ will have the duration be 1 millisecond. Numbers greater than 1000 are
+ invalid and 1 millisecond will be used instead.
Example:
diff --git a/Documentation/devicetree/bindings/net/phy.txt b/Documentation/devicetree/bindings/net/phy.txt
index bb8c742eb8c..7cd18fbfcf7 100644
--- a/Documentation/devicetree/bindings/net/phy.txt
+++ b/Documentation/devicetree/bindings/net/phy.txt
@@ -14,10 +14,20 @@ Required properties:
- linux,phandle : phandle for this node; likely referenced by an
ethernet controller node.
+Optional Properties:
+
+- compatible: Compatible list, may contain
+ "ethernet-phy-ieee802.3-c22" or "ethernet-phy-ieee802.3-c45" for
+ PHYs that implement IEEE802.3 clause 22 or IEEE802.3 clause 45
+ specifications. If neither of these are specified, the default is to
+ assume clause 22. The compatible list may also contain other
+ elements.
+
Example:
ethernet-phy@0 {
- linux,phandle = <2452000>
+ compatible = "ethernet-phy-ieee802.3-c22";
+ linux,phandle = <2452000>;
interrupt-parent = <40000>;
interrupts = <35 1>;
reg = <0>;
diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
index 1f62623f8c3..060bbf098ef 100644
--- a/Documentation/devicetree/bindings/net/stmmac.txt
+++ b/Documentation/devicetree/bindings/net/stmmac.txt
@@ -1,7 +1,8 @@
* STMicroelectronics 10/100/1000 Ethernet driver (GMAC)
Required properties:
-- compatible: Should be "st,spear600-gmac"
+- compatible: Should be "snps,dwmac-<ip_version>" "snps,dwmac"
+ For backwards compatibility: "st,spear600-gmac" is also supported.
- reg: Address and length of the register set for the device
- interrupt-parent: Should be the phandle for the interrupt controller
that services interrupts for this device
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 56000b33340..61d1a89baea 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -249,15 +249,6 @@ Who: Ravikiran Thirumalai <kiran@scalex86.org>
---------------------------
-What: Code that is now under CONFIG_WIRELESS_EXT_SYSFS
- (in net/core/net-sysfs.c)
-When: 3.5
-Why: Over 1K .text/.data size reduction, data is available in other
- ways (ioctls)
-Who: Johannes Berg <johannes@sipsolutions.net>
-
----------------------------
-
What: sysfs ui for changing p4-clockmod parameters
When: September 2009
Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
@@ -414,21 +405,6 @@ Who: Jean Delvare <khali@linux-fr.org>
----------------------------
-What: xt_connlimit rev 0
-When: 2012
-Who: Jan Engelhardt <jengelh@medozas.de>
-Files: net/netfilter/xt_connlimit.c
-
-----------------------------
-
-What: ipt_addrtype match include file
-When: 2012
-Why: superseded by xt_addrtype
-Who: Florian Westphal <fw@strlen.de>
-Files: include/linux/netfilter_ipv4/ipt_addrtype.h
-
-----------------------------
-
What: i2c_driver.attach_adapter
i2c_driver.detach_adapter
When: September 2011
@@ -449,6 +425,19 @@ Who: Hans Verkuil <hans.verkuil@cisco.com>
----------------------------
+What: CONFIG_CFG80211_WEXT
+When: as soon as distributions ship new wireless tools, ie. wpa_supplicant 1.0
+ and NetworkManager/connman/etc. that are able to use nl80211
+Why: Wireless extensions are deprecated, and userland tools are moving to
+ using nl80211. New drivers are no longer using wireless extensions,
+ and while there might still be old drivers, both new drivers and new
+ userland no longer needs them and they can't be used for an feature
+ developed in the past couple of years. As such, compatibility with
+ wireless extensions in new drivers will be removed.
+Who: Johannes Berg <johannes@sipsolutions.net>
+
+----------------------------
+
What: g_file_storage driver
When: 3.8
Why: This driver has been superseded by g_mass_storage.
@@ -589,6 +578,13 @@ Why: Remount currently allows changing bound subsystems and
----------------------------
+What: xt_recent rev 0
+When: 2013
+Who: Pablo Neira Ayuso <pablo@netfilter.org>
+Files: net/netfilter/xt_recent.c
+
+----------------------------
+
What: KVM debugfs statistics
When: 2013
Why: KVM tracepoints provide mostly equivalent information in a much more
diff --git a/Documentation/networking/batman-adv.txt b/Documentation/networking/batman-adv.txt
index 75a592365af..8f3ae4a6147 100644
--- a/Documentation/networking/batman-adv.txt
+++ b/Documentation/networking/batman-adv.txt
@@ -211,6 +211,11 @@ The debug output can be changed at runtime using the file
will enable debug messages for when routes change.
+Counters for different types of packets entering and leaving the
+batman-adv module are available through ethtool:
+
+# ethtool --statistics bat0
+
BATCTL
------
diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt
index bfea8a33890..6b1c7110534 100644
--- a/Documentation/networking/bonding.txt
+++ b/Documentation/networking/bonding.txt
@@ -1210,7 +1210,7 @@ options, you may wish to use the "max_bonds" module parameter,
documented above.
To create multiple bonding devices with differing options, it is
-preferrable to use bonding parameters exported by sysfs, documented in the
+preferable to use bonding parameters exported by sysfs, documented in the
section below.
For versions of bonding without sysfs support, the only means to
@@ -1950,7 +1950,7 @@ access to fail over to. Additionally, the bonding load balance modes
support link monitoring of their members, so if individual links fail,
the load will be rebalanced across the remaining devices.
- See Section 13, "Configuring Bonding for Maximum Throughput"
+ See Section 12, "Configuring Bonding for Maximum Throughput"
for information on configuring bonding with one peer device.
11.2 High Availability in a Multiple Switch Topology
@@ -2620,7 +2620,7 @@ be found at:
https://lists.sourceforge.net/lists/listinfo/bonding-devel
- Discussions regarding the developpement of the bonding driver take place
+ Discussions regarding the development of the bonding driver take place
on the main Linux network mailing list, hosted at vger.kernel.org. The list
address is:
diff --git a/Documentation/networking/bridge.txt b/Documentation/networking/bridge.txt
index a7ba5e4e2c9..a27cb6214ed 100644
--- a/Documentation/networking/bridge.txt
+++ b/Documentation/networking/bridge.txt
@@ -1,7 +1,14 @@
In order to use the Ethernet bridging functionality, you'll need the
-userspace tools. These programs and documentation are available
-at http://www.linuxfoundation.org/en/Net:Bridge. The download page is
-http://prdownloads.sourceforge.net/bridge.
+userspace tools.
+
+Documentation for Linux bridging is on:
+ http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge
+
+The bridge-utilities are maintained at:
+ git://git.kernel.org/pub/scm/linux/kernel/git/shemminger/bridge-utils.git
+
+Additionally, the iproute2 utilities can be used to configure
+bridge devices.
If you still have questions, don't hesitate to post to the mailing list
(more info https://lists.linux-foundation.org/mailman/listinfo/bridge).
diff --git a/Documentation/networking/caif/Linux-CAIF.txt b/Documentation/networking/caif/Linux-CAIF.txt
index e52fd62bef3..0aa4bd381be 100644
--- a/Documentation/networking/caif/Linux-CAIF.txt
+++ b/Documentation/networking/caif/Linux-CAIF.txt
@@ -19,60 +19,36 @@ and host. Currently, UART and Loopback are available for Linux.
Architecture:
------------
The implementation of CAIF is divided into:
-* CAIF Socket Layer, Kernel API, and Net Device.
+* CAIF Socket Layer and GPRS IP Interface.
* CAIF Core Protocol Implementation
* CAIF Link Layer, implemented as NET devices.
RTNL
!
- ! +------+ +------+ +------+
- ! +------+! +------+! +------+!
- ! ! Sock !! !Kernel!! ! Net !!
- ! ! API !+ ! API !+ ! Dev !+ <- CAIF Client APIs
- ! +------+ +------! +------+
- ! ! ! !
- ! +----------!----------+
- ! +------+ <- CAIF Protocol Implementation
- +-------> ! CAIF !
- ! Core !
- +------+
- +--------!--------+
- ! !
- +------+ +-----+
- ! ! ! TTY ! <- Link Layer (Net Devices)
- +------+ +-----+
-
-
-Using the Kernel API
-----------------------
-The Kernel API is used for accessing CAIF channels from the
-kernel.
-The user of the API has to implement two callbacks for receive
-and control.
-The receive callback gives a CAIF packet as a SKB. The control
-callback will
-notify of channel initialization complete, and flow-on/flow-
-off.
-
-
- struct caif_device caif_dev = {
- .caif_config = {
- .name = "MYDEV"
- .type = CAIF_CHTY_AT
- }
- .receive_cb = my_receive,
- .control_cb = my_control,
- };
- caif_add_device(&caif_dev);
- caif_transmit(&caif_dev, skb);
-
-See the caif_kernel.h for details about the CAIF kernel API.
+ ! +------+ +------+
+ ! +------+! +------+!
+ ! ! IP !! !Socket!!
+ +-------> !interf!+ ! API !+ <- CAIF Client APIs
+ ! +------+ +------!
+ ! ! !
+ ! +-----------+
+ ! !
+ ! +------+ <- CAIF Core Protocol
+ ! ! CAIF !
+ ! ! Core !
+ ! +------+
+ ! +----------!---------+
+ ! ! ! !
+ ! +------+ +-----+ +------+
+ +--> ! HSI ! ! TTY ! ! USB ! <- Link Layer (Net Devices)
+ +------+ +-----+ +------+
+
I M P L E M E N T A T I O N
===========================
-===========================
+
CAIF Core Protocol Layer
=========================================
@@ -88,17 +64,13 @@ The Core CAIF implementation contains:
- Simple implementation of CAIF.
- Layered architecture (a la Streams), each layer in the CAIF
specification is implemented in a separate c-file.
- - Clients must implement PHY layer to access physical HW
- with receive and transmit functions.
- Clients must call configuration function to add PHY layer.
- Clients must implement CAIF layer to consume/produce
CAIF payload with receive and transmit functions.
- Clients must call configuration function to add and connect the
Client layer.
- When receiving / transmitting CAIF Packets (cfpkt), ownership is passed
- to the called function (except for framing layers' receive functions
- or if a transmit function returns an error, in which case the caller
- must free the packet).
+ to the called function (except for framing layers' receive function)
Layered Architecture
--------------------
@@ -109,11 +81,6 @@ Implementation. The support functions include:
CAIF Packet has functions for creating, destroying and adding content
and for adding/extracting header and trailers to protocol packets.
- - CFLST CAIF list implementation.
-
- - CFGLUE CAIF Glue. Contains OS Specifics, such as memory
- allocation, endianness, etc.
-
The CAIF Protocol implementation contains:
- CFCNFG CAIF Configuration layer. Configures the CAIF Protocol
@@ -128,7 +95,7 @@ The CAIF Protocol implementation contains:
control and remote shutdown requests.
- CFVEI CAIF VEI layer. Handles CAIF AT Channels on VEI (Virtual
- External Interface). This layer encodes/decodes VEI frames.
+ External Interface). This layer encodes/decodes VEI frames.
- CFDGML CAIF Datagram layer. Handles CAIF Datagram layer (IP
traffic), encodes/decodes Datagram frames.
@@ -170,7 +137,7 @@ The CAIF Protocol implementation contains:
+---------+ +---------+
! !
+---------+ +---------+
- | | | Serial |
+ | | | Serial |
| | | CFSERL |
+---------+ +---------+
@@ -186,24 +153,20 @@ In this layered approach the following "rules" apply.
layer->dn->transmit(layer->dn, packet);
-Linux Driver Implementation
+CAIF Socket and IP interface
===========================
-Linux GPRS Net Device and CAIF socket are implemented on top of the
-CAIF Core protocol. The Net device and CAIF socket have an instance of
+The IP interface and CAIF socket API are implemented on top of the
+CAIF Core protocol. The IP Interface and CAIF socket have an instance of
'struct cflayer', just like the CAIF Core protocol stack.
Net device and Socket implement the 'receive()' function defined by
'struct cflayer', just like the rest of the CAIF stack. In this way, transmit and
receive of packets is handled as by the rest of the layers: the 'dn->transmit()'
function is called in order to transmit data.
-The layer on top of the CAIF Core implementation is
-sometimes referred to as the "Client layer".
-
-
Configuration of Link Layer
---------------------------
-The Link Layer is implemented as Linux net devices (struct net_device).
+The Link Layer is implemented as Linux network devices (struct net_device).
Payload handling and registration is done using standard Linux mechanisms.
The CAIF Protocol relies on a loss-less link layer without implementing
diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
index ac295399f0d..820f55344ed 100644
--- a/Documentation/networking/can.txt
+++ b/Documentation/networking/can.txt
@@ -22,7 +22,8 @@ This file contains
4.1.2 RAW socket option CAN_RAW_ERR_FILTER
4.1.3 RAW socket option CAN_RAW_LOOPBACK
4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
- 4.1.5 RAW socket returned message flags
+ 4.1.5 RAW socket option CAN_RAW_FD_FRAMES
+ 4.1.6 RAW socket returned message flags
4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
4.3 connected transport protocols (SOCK_SEQPACKET)
4.4 unconnected transport protocols (SOCK_DGRAM)
@@ -41,7 +42,8 @@ This file contains
6.5.1 Netlink interface to set/get devices properties
6.5.2 Setting the CAN bit-timing
6.5.3 Starting and stopping the CAN network device
- 6.6 supported CAN hardware
+ 6.6 CAN FD (flexible data rate) driver support
+ 6.7 supported CAN hardware
7 Socket CAN resources
@@ -232,16 +234,16 @@ solution for a couple of reasons:
arbitration problems and error frames caused by the different
ECUs. The occurrence of detected errors are important for diagnosis
and have to be logged together with the exact timestamp. For this
- reason the CAN interface driver can generate so called Error Frames
- that can optionally be passed to the user application in the same
- way as other CAN frames. Whenever an error on the physical layer
+ reason the CAN interface driver can generate so called Error Message
+ Frames that can optionally be passed to the user application in the
+ same way as other CAN frames. Whenever an error on the physical layer
or the MAC layer is detected (e.g. by the CAN controller) the driver
- creates an appropriate error frame. Error frames can be requested by
- the user application using the common CAN filter mechanisms. Inside
- this filter definition the (interested) type of errors may be
- selected. The reception of error frames is disabled by default.
- The format of the CAN error frame is briefly described in the Linux
- header file "include/linux/can/error.h".
+ creates an appropriate error message frame. Error messages frames can
+ be requested by the user application using the common CAN filter
+ mechanisms. Inside this filter definition the (interested) type of
+ errors may be selected. The reception of error messages is disabled
+ by default. The format of the CAN error message frame is briefly
+ described in the Linux header file "include/linux/can/error.h".
4. How to use Socket CAN
------------------------
@@ -273,7 +275,7 @@ solution for a couple of reasons:
struct can_frame {
canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
- __u8 can_dlc; /* data length code: 0 .. 8 */
+ __u8 can_dlc; /* frame payload length in byte (0 .. 8) */
__u8 data[8] __attribute__((aligned(8)));
};
@@ -375,6 +377,51 @@ solution for a couple of reasons:
nbytes = sendto(s, &frame, sizeof(struct can_frame),
0, (struct sockaddr*)&addr, sizeof(addr));
+ Remark about CAN FD (flexible data rate) support:
+
+ Generally the handling of CAN FD is very similar to the formerly described
+ examples. The new CAN FD capable CAN controllers support two different
+ bitrates for the arbitration phase and the payload phase of the CAN FD frame
+ and up to 64 bytes of payload. This extended payload length breaks all the
+ kernel interfaces (ABI) which heavily rely on the CAN frame with fixed eight
+ bytes of payload (struct can_frame) like the CAN_RAW socket. Therefore e.g.
+ the CAN_RAW socket supports a new socket option CAN_RAW_FD_FRAMES that
+ switches the socket into a mode that allows the handling of CAN FD frames
+ and (legacy) CAN frames simultaneously (see section 4.1.5).
+
+ The struct canfd_frame is defined in include/linux/can.h:
+
+ struct canfd_frame {
+ canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
+ __u8 len; /* frame payload length in byte (0 .. 64) */
+ __u8 flags; /* additional flags for CAN FD */
+ __u8 __res0; /* reserved / padding */
+ __u8 __res1; /* reserved / padding */
+ __u8 data[64] __attribute__((aligned(8)));
+ };
+
+ The struct canfd_frame and the existing struct can_frame have the can_id,
+ the payload length and the payload data at the same offset inside their
+ structures. This allows to handle the different structures very similar.
+ When the content of a struct can_frame is copied into a struct canfd_frame
+ all structure elements can be used as-is - only the data[] becomes extended.
+
+ When introducing the struct canfd_frame it turned out that the data length
+ code (DLC) of the struct can_frame was used as a length information as the
+ length and the DLC has a 1:1 mapping in the range of 0 .. 8. To preserve
+ the easy handling of the length information the canfd_frame.len element
+ contains a plain length value from 0 .. 64. So both canfd_frame.len and
+ can_frame.can_dlc are equal and contain a length information and no DLC.
+ For details about the distinction of CAN and CAN FD capable devices and
+ the mapping to the bus-relevant data length code (DLC), see chapter 6.6.
+
+ The length of the two CAN(FD) frame structures define the maximum transfer
+ unit (MTU) of the CAN(FD) network interface and skbuff data length. Two
+ definitions are specified for CAN specific MTUs in include/linux/can.h :
+
+ #define CAN_MTU (sizeof(struct can_frame)) == 16 => 'legacy' CAN frame
+ #define CANFD_MTU (sizeof(struct canfd_frame)) == 72 => CAN FD frame
+
4.1 RAW protocol sockets with can_filters (SOCK_RAW)
Using CAN_RAW sockets is extensively comparable to the commonly
@@ -383,7 +430,7 @@ solution for a couple of reasons:
defaults are set at RAW socket binding time:
- The filters are set to exactly one filter receiving everything
- - The socket only receives valid data frames (=> no error frames)
+ - The socket only receives valid data frames (=> no error message frames)
- The loopback of sent CAN frames is enabled (see chapter 3.2)
- The socket does not receive its own sent frames (in loopback mode)
@@ -434,7 +481,7 @@ solution for a couple of reasons:
4.1.2 RAW socket option CAN_RAW_ERR_FILTER
As described in chapter 3.4 the CAN interface driver can generate so
- called Error Frames that can optionally be passed to the user
+ called Error Message Frames that can optionally be passed to the user
application in the same way as other CAN frames. The possible
errors are divided into different error classes that may be filtered
using the appropriate error mask. To register for every possible
@@ -472,7 +519,69 @@ solution for a couple of reasons:
setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
&recv_own_msgs, sizeof(recv_own_msgs));
- 4.1.5 RAW socket returned message flags
+ 4.1.5 RAW socket option CAN_RAW_FD_FRAMES
+
+ CAN FD support in CAN_RAW sockets can be enabled with a new socket option
+ CAN_RAW_FD_FRAMES which is off by default. When the new socket option is
+ not supported by the CAN_RAW socket (e.g. on older kernels), switching the
+ CAN_RAW_FD_FRAMES option returns the error -ENOPROTOOPT.
+
+ Once CAN_RAW_FD_FRAMES is enabled the application can send both CAN frames
+ and CAN FD frames. OTOH the application has to handle CAN and CAN FD frames
+ when reading from the socket.
+
+ CAN_RAW_FD_FRAMES enabled: CAN_MTU and CANFD_MTU are allowed
+ CAN_RAW_FD_FRAMES disabled: only CAN_MTU is allowed (default)
+
+ Example:
+ [ remember: CANFD_MTU == sizeof(struct canfd_frame) ]
+
+ struct canfd_frame cfd;
+
+ nbytes = read(s, &cfd, CANFD_MTU);
+
+ if (nbytes == CANFD_MTU) {
+ printf("got CAN FD frame with length %d\n", cfd.len);
+ /* cfd.flags contains valid data */
+ } else if (nbytes == CAN_MTU) {
+ printf("got legacy CAN frame with length %d\n", cfd.len);
+ /* cfd.flags is undefined */
+ } else {
+ fprintf(stderr, "read: invalid CAN(FD) frame\n");
+ return 1;
+ }
+
+ /* the content can be handled independently from the received MTU size */
+
+ printf("can_id: %X data length: %d data: ", cfd.can_id, cfd.len);
+ for (i = 0; i < cfd.len; i++)
+ printf("%02X ", cfd.data[i]);
+
+ When reading with size CANFD_MTU only returns CAN_MTU bytes that have
+ been received from the socket a legacy CAN frame has been read into the
+ provided CAN FD structure. Note that the canfd_frame.flags data field is
+ not specified in the struct can_frame and therefore it is only valid in
+ CANFD_MTU sized CAN FD frames.
+
+ As long as the payload length is <=8 the received CAN frames from CAN FD
+ capable CAN devices can be received and read by legacy sockets too. When
+ user-generated CAN FD frames have a payload length <=8 these can be send
+ by legacy CAN network interfaces too. Sending CAN FD frames with payload
+ length > 8 to a legacy CAN network interface returns an -EMSGSIZE error.
+
+ Implementation hint for new CAN applications:
+
+ To build a CAN FD aware application use struct canfd_frame as basic CAN
+ data structure for CAN_RAW based applications. When the application is
+ executed on an older Linux kernel and switching the CAN_RAW_FD_FRAMES
+ socket option returns an error: No problem. You'll get legacy CAN frames
+ or CAN FD frames and can process them the same way.
+
+ When sending to CAN devices make sure that the device is capable to handle
+ CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU.
+ The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
+
+ 4.1.6 RAW socket returned message flags
When using recvmsg() call, the msg->msg_flags may contain following flags:
@@ -527,7 +636,7 @@ solution for a couple of reasons:
rcvlist_all - list for unfiltered entries (no filter operations)
rcvlist_eff - list for single extended frame (EFF) entries
- rcvlist_err - list for error frames masks
+ rcvlist_err - list for error message frames masks
rcvlist_fil - list for mask/value filters
rcvlist_inv - list for mask/value filters (inverse semantic)
rcvlist_sff - list for single standard frame (SFF) entries
@@ -573,10 +682,13 @@ solution for a couple of reasons:
dev->type = ARPHRD_CAN; /* the netdevice hardware type */
dev->flags = IFF_NOARP; /* CAN has no arp */
- dev->mtu = sizeof(struct can_frame);
+ dev->mtu = CAN_MTU; /* sizeof(struct can_frame) -> legacy CAN interface */
- The struct can_frame is the payload of each socket buffer in the
- protocol family PF_CAN.
+ or alternative, when the controller supports CAN with flexible data rate:
+ dev->mtu = CANFD_MTU; /* sizeof(struct canfd_frame) -> CAN FD interface */
+
+ The struct can_frame or struct canfd_frame is the payload of each socket
+ buffer (skbuff) in the protocol family PF_CAN.
6.2 local loopback of sent frames
@@ -784,15 +896,41 @@ solution for a couple of reasons:
$ ip link set canX type can restart-ms 100
Alternatively, the application may realize the "bus-off" condition
- by monitoring CAN error frames and do a restart when appropriate with
- the command:
+ by monitoring CAN error message frames and do a restart when
+ appropriate with the command:
$ ip link set canX type can restart
- Note that a restart will also create a CAN error frame (see also
- chapter 3.4).
+ Note that a restart will also create a CAN error message frame (see
+ also chapter 3.4).
+
+ 6.6 CAN FD (flexible data rate) driver support
+
+ CAN FD capable CAN controllers support two different bitrates for the
+ arbitration phase and the payload phase of the CAN FD frame. Therefore a
+ second bittiming has to be specified in order to enable the CAN FD bitrate.
+
+ Additionally CAN FD capable CAN controllers support up to 64 bytes of
+ payload. The representation of this length in can_frame.can_dlc and
+ canfd_frame.len for userspace applications and inside the Linux network
+ layer is a plain value from 0 .. 64 instead of the CAN 'data length code'.
+ The data length code was a 1:1 mapping to the payload length in the legacy
+ CAN frames anyway. The payload length to the bus-relevant DLC mapping is
+ only performed inside the CAN drivers, preferably with the helper
+ functions can_dlc2len() and can_len2dlc().
+
+ The CAN netdevice driver capabilities can be distinguished by the network
+ devices maximum transfer unit (MTU):
+
+ MTU = 16 (CAN_MTU) => sizeof(struct can_frame) => 'legacy' CAN device
+ MTU = 72 (CANFD_MTU) => sizeof(struct canfd_frame) => CAN FD capable device
+
+ The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
+ N.B. CAN FD capable devices can also handle and send legacy CAN frames.
+
+ FIXME: Add details about the CAN FD controller configuration when available.
- 6.6 Supported CAN hardware
+ 6.7 Supported CAN hardware
Please check the "Kconfig" file in "drivers/net/can" to get an actual
list of the support CAN hardware. On the Socket CAN project website
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 6f896b94abd..406a5226220 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -468,6 +468,19 @@ tcp_syncookies - BOOLEAN
SYN flood warnings in logs not being really flooded, your server
is seriously misconfigured.
+tcp_fastopen - INTEGER
+ Enable TCP Fast Open feature (draft-ietf-tcpm-fastopen) to send data
+ in the opening SYN packet. To use this feature, the client application
+ must not use connect(). Instead, it should use sendmsg() or sendto()
+ with MSG_FASTOPEN flag which performs a TCP handshake automatically.
+
+ The values (bitmap) are:
+ 1: Enables sending data in the opening SYN on the client
+ 5: Enables sending data in the opening SYN on the client regardless
+ of cookie availability.
+
+ Default: 0
+
tcp_syn_retries - INTEGER
Number of times initial SYNs for an active TCP connection attempt
will be retransmitted. Should not be higher than 255. Default value
@@ -551,6 +564,25 @@ tcp_thin_dupack - BOOLEAN
Documentation/networking/tcp-thin.txt
Default: 0
+tcp_limit_output_bytes - INTEGER
+ Controls TCP Small Queue limit per tcp socket.
+ TCP bulk sender tends to increase packets in flight until it
+ gets losses notifications. With SNDBUF autotuning, this can
+ result in a large amount of packets queued in qdisc/device
+ on the local machine, hurting latency of other flows, for
+ typical pfifo_fast qdiscs.
+ tcp_limit_output_bytes limits the number of bytes on qdisc
+ or device to reduce artificial RTT/cwnd and reduce bufferbloat.
+ Note: For GSO/TSO enabled flows, we try to have at least two
+ packets in flight. Reducing tcp_limit_output_bytes might also
+ reduce the size of individual GSO packet (64KB being the max)
+ Default: 131072
+
+tcp_challenge_ack_limit - INTEGER
+ Limits number of Challenge ACK sent per second, as recommended
+ in RFC 5961 (Improving TCP's Robustness to Blind In-Window Attacks)
+ Default: 100
+
UDP variables:
udp_mem - vector of 3 INTEGERs: min, pressure, max
@@ -857,9 +889,19 @@ accept_source_route - BOOLEAN
FALSE (host)
accept_local - BOOLEAN
- Accept packets with local source addresses. In combination with
- suitable routing, this can be used to direct packets between two
- local interfaces over the wire and have them accepted properly.
+ Accept packets with local source addresses. In combination
+ with suitable routing, this can be used to direct packets
+ between two local interfaces over the wire and have them
+ accepted properly.
+
+ rp_filter must be set to a non-zero value in order for
+ accept_local to have an effect.
+
+ default FALSE
+
+route_localnet - BOOLEAN
+ Do not consider loopback addresses as martian source or destination
+ while routing. This enables the use of 127/8 for local routing purposes.
default FALSE
rp_filter - INTEGER
@@ -1398,6 +1440,20 @@ path_max_retrans - INTEGER
Default: 5
+pf_retrans - INTEGER
+ The number of retransmissions that will be attempted on a given path
+ before traffic is redirected to an alternate transport (should one
+ exist). Note this is distinct from path_max_retrans, as a path that
+ passes the pf_retrans threshold can still be used. Its only
+ deprioritized when a transmission path is selected by the stack. This
+ setting is primarily used to enable fast failover mechanisms without
+ having to reduce path_max_retrans to a very low value. See:
+ http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt
+ for details. Note also that a value of pf_retrans > path_max_retrans
+ disables this feature
+
+ Default: 0
+
rto_initial - INTEGER
The initial round trip timeout value in milliseconds that will be used
in calculating round trip times. This is the initial time interval
diff --git a/Documentation/networking/openvswitch.txt b/Documentation/networking/openvswitch.txt
index b8a048b8df3..8fa2dd1e792 100644
--- a/Documentation/networking/openvswitch.txt
+++ b/Documentation/networking/openvswitch.txt
@@ -118,7 +118,7 @@ essentially like this, ignoring metadata:
Naively, to add VLAN support, it makes sense to add a new "vlan" flow
key attribute to contain the VLAN tag, then continue to decode the
encapsulated headers beyond the VLAN tag using the existing field
-definitions. With this change, an TCP packet in VLAN 10 would have a
+definitions. With this change, a TCP packet in VLAN 10 would have a
flow key much like this:
eth(...), vlan(vid=10, pcp=0), eth_type(0x0800), ip(proto=6, ...), tcp(...)
diff --git a/Documentation/networking/s2io.txt b/Documentation/networking/s2io.txt
index 4be0c039edb..d2a9f43b554 100644
--- a/Documentation/networking/s2io.txt
+++ b/Documentation/networking/s2io.txt
@@ -136,16 +136,6 @@ For more information, please review the AMD8131 errata at
http://vip.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/
26310_AMD-8131_HyperTransport_PCI-X_Tunnel_Revision_Guide_rev_3_18.pdf
-6. Available Downloads
-Neterion "s2io" driver in Red Hat and Suse 2.6-based distributions is kept up
-to date, also the latest "s2io" code (including support for 2.4 kernels) is
-available via "Support" link on the Neterion site: http://www.neterion.com.
-
-For Xframe User Guide (Programming manual), visit ftp site ns1.s2io.com,
-user: linuxdocs password: HALdocs
-
-7. Support
+6. Support
For further support please contact either your 10GbE Xframe NIC vendor (IBM,
-HP, SGI etc.) or click on the "Support" link on the Neterion site:
-http://www.neterion.com.
-
+HP, SGI etc.)
diff --git a/Documentation/networking/stmmac.txt b/Documentation/networking/stmmac.txt
index 5cb9a197246..c676b9cedbd 100644
--- a/Documentation/networking/stmmac.txt
+++ b/Documentation/networking/stmmac.txt
@@ -257,9 +257,11 @@ reset procedure etc).
o Makefile
o stmmac_main.c: main network device driver;
o stmmac_mdio.c: mdio functions;
+ o stmmac_pci: PCI driver;
+ o stmmac_platform.c: platform driver
o stmmac_ethtool.c: ethtool support;
o stmmac_timer.[ch]: timer code used for mitigating the driver dma interrupts
- Only tested on ST40 platforms based.
+ (only tested on ST40 platforms based);
o stmmac.h: private driver structure;
o common.h: common definitions and VFTs;
o descs.h: descriptor structure definitions;
@@ -269,9 +271,11 @@ reset procedure etc).
o dwmac100_core: MAC 100 core and dma code;
o dwmac100_dma.c: dma funtions for the MAC chip;
o dwmac1000.h: specific header file for the MAC;
- o dwmac_lib.c: generic DMA functions shared among chips
- o enh_desc.c: functions for handling enhanced descriptors
- o norm_desc.c: functions for handling normal descriptors
+ o dwmac_lib.c: generic DMA functions shared among chips;
+ o enh_desc.c: functions for handling enhanced descriptors;
+ o norm_desc.c: functions for handling normal descriptors;
+ o chain_mode.c/ring_mode.c:: functions to manage RING/CHAINED modes;
+ o mmc_core.c/mmc.h: Management MAC Counters;
5) Debug Information
@@ -304,7 +308,27 @@ All these are only useful during the developing stage
and should never enabled inside the code for general usage.
In fact, these can generate an huge amount of debug messages.
-6) TODO:
+6) Energy Efficient Ethernet
+
+Energy Efficient Ethernet(EEE) enables IEEE 802.3 MAC sublayer along
+with a family of Physical layer to operate in the Low power Idle(LPI)
+mode. The EEE mode supports the IEEE 802.3 MAC operation at 100Mbps,
+1000Mbps & 10Gbps.
+
+The LPI mode allows power saving by switching off parts of the
+communication device functionality when there is no data to be
+transmitted & received. The system on both the side of the link can
+disable some functionalities & save power during the period of low-link
+utilization. The MAC controls whether the system should enter or exit
+the LPI mode & communicate this to PHY.
+
+As soon as the interface is opened, the driver verifies if the EEE can
+be supported. This is done by looking at both the DMA HW capability
+register and the PHY devices MCD registers.
+To enter in Tx LPI mode the driver needs to have a software timer
+that enable and disable the LPI mode when there is nothing to be
+transmitted.
+
+7) TODO:
o XGMAC is not supported.
- o Add the EEE - Energy Efficient Ethernet
o Add the PTP - precision time protocol
diff --git a/Documentation/networking/vxge.txt b/Documentation/networking/vxge.txt
index d2e2997e6fa..bb76c667a47 100644
--- a/Documentation/networking/vxge.txt
+++ b/Documentation/networking/vxge.txt
@@ -91,10 +91,3 @@ v) addr_learn_en
virtualization environment.
Valid range: 0,1 (disabled, enabled respectively)
Default: 0
-
-4) Troubleshooting:
--------------------
-
-To resolve an issue with the source code or X3100 series adapter, please collect
-the statistics, register dumps using ethool, relevant logs and email them to
-support@neterion.com.
diff --git a/Documentation/nfc/nfc-hci.txt b/Documentation/nfc/nfc-hci.txt
index 320f9336c78..89a339c9b07 100644
--- a/Documentation/nfc/nfc-hci.txt
+++ b/Documentation/nfc/nfc-hci.txt
@@ -178,3 +178,36 @@ ANY_GET_PARAMETER to the reader A gate to get information on the target
that was discovered).
Typically, such an event will be propagated to NFC Core from MSGRXWQ context.
+
+Error management
+----------------
+
+Errors that occur synchronously with the execution of an NFC Core request are
+simply returned as the execution result of the request. These are easy.
+
+Errors that occur asynchronously (e.g. in a background protocol handling thread)
+must be reported such that upper layers don't stay ignorant that something
+went wrong below and know that expected events will probably never happen.
+Handling of these errors is done as follows:
+
+- driver (pn544) fails to deliver an incoming frame: it stores the error such
+that any subsequent call to the driver will result in this error. Then it calls
+the standard nfc_shdlc_recv_frame() with a NULL argument to report the problem
+above. shdlc stores a EREMOTEIO sticky status, which will trigger SMW to
+report above in turn.
+
+- SMW is basically a background thread to handle incoming and outgoing shdlc
+frames. This thread will also check the shdlc sticky status and report to HCI
+when it discovers it is not able to run anymore because of an unrecoverable
+error that happened within shdlc or below. If the problem occurs during shdlc
+connection, the error is reported through the connect completion.
+
+- HCI: if an internal HCI error happens (frame is lost), or HCI is reported an
+error from a lower layer, HCI will either complete the currently executing
+command with that error, or notify NFC Core directly if no command is executing.
+
+- NFC Core: when NFC Core is notified of an error from below and polling is
+active, it will send a tag discovered event with an empty tag list to the user
+space to let it know that the poll operation will never be able to detect a tag.
+If polling is not active and the error was sticky, lower levels will return it
+at next invocation.