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author | Paul Bolle <pebolle@tiscali.nl> | 2011-03-11 11:24:52 +0100 |
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committer | Takashi Iwai <tiwai@suse.de> | 2011-03-11 15:22:00 +0100 |
commit | 5cd2ad81f912c8535491f541108b655f4552dff9 (patch) | |
tree | 3dc74dc647e858967a33c777af91ee65e1dc6ac8 /sound/pci | |
parent | 88a8516a2128a6d078a106ead48092240e8a138f (diff) | |
download | linux-3.10-5cd2ad81f912c8535491f541108b655f4552dff9.tar.gz linux-3.10-5cd2ad81f912c8535491f541108b655f4552dff9.tar.bz2 linux-3.10-5cd2ad81f912c8535491f541108b655f4552dff9.zip |
ALSA: intel8x0m: wait a bit before warm reset check
At every resume a laptop I use prints this message (at KERN_ERR level):
ALSA sound/pci/intel8x0m.c:904: AC'97 warm reset still in progress? [0x2]
The thing to note here is that 0x2 corresponds to ICH_AC97COLD. Ie, what
seems to be happening is that the register involved indicated a warm
reset for some time (as the ICH_AC97WARM bit was set) but by the time
the warning is printed, and that same register is checked again, that
bit is already cleared and only the ICH_AC97COLD bit is still set.
It turns out a warm reset needs some time to settle, but it is currently
checked right away. The test therefore fails the first time it is done
and schedule_timeout_uninterruptible() will be called. Once we return
from that jiffies is already (far) past end_time on this laptop, so we
exit the loop, print a warning, and exit the function while the warm
reset actually succeeded.
A way to fix this is to call usleep_range() after writing to the
register involved. A handful of tests suggest 500 usecs is a safe value.
(This might punish the "finish cold reset" case, but on this laptop such
a cold reset apparently never happens, so I can't say for sure.)
While we're at it drop the extra single tick from end_time, as it looks
rather silly.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/pci')
-rw-r--r-- | sound/pci/intel8x0m.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/sound/pci/intel8x0m.c b/sound/pci/intel8x0m.c index 13cec1e5ced..b1c926cd281 100644 --- a/sound/pci/intel8x0m.c +++ b/sound/pci/intel8x0m.c @@ -894,7 +894,8 @@ static int snd_intel8x0m_ich_chip_init(struct intel8x0m *chip, int probing) /* finish cold or do warm reset */ cnt |= (cnt & ICH_AC97COLD) == 0 ? ICH_AC97COLD : ICH_AC97WARM; iputdword(chip, ICHREG(GLOB_CNT), cnt); - end_time = (jiffies + (HZ / 4)) + 1; + usleep_range(500, 1000); /* give warm reset some time */ + end_time = jiffies + HZ / 4; do { if ((igetdword(chip, ICHREG(GLOB_CNT)) & ICH_AC97WARM) == 0) goto __ok; |