drm/i915: Support for ns2501-DVO

This patch adds support for the ns2501 DVO, found in some older Fujitsu/Siemens Labtops.
It is in the state of "works for me".
Includes now proper DPMS support. Includes switching between resolutions -
from 640x480 to 1024x768.
Currently assumes that the native display resolution is 1024x768.

The ns2501 seems to be rather critical - if the output PLL is not
running, the chip doesn't seem to be clocked and then doesn't react
on i2c messages. Thus, a quick'n-dirty trick ensures that the DVO
is active before submitting any i2c messages to it. This is
probably to be reviewed.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=17902
Signed-off-by: Thomas Richter <thor@math.tu-berlin.de>
[danvet: fixup whitespace fail.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

5 files changed, 596 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index b0bacdba6d7..0f2c5493242 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -40,6 +40,7 @@ i915-y := i915_drv.o i915_dma.o i915_irq.o \
 	  dvo_ivch.o \
 	  dvo_tfp410.o \
 	  dvo_sil164.o \
+	  dvo_ns2501.o \
 	  i915_gem_dmabuf.o
 
 i915-$(CONFIG_COMPAT)   += i915_ioc32.o
diff --git a/drivers/gpu/drm/i915/dvo.h b/drivers/gpu/drm/i915/dvo.h
index 58914691a77..0c8ac4d92de 100644
--- a/drivers/gpu/drm/i915/dvo.h
+++ b/drivers/gpu/drm/i915/dvo.h
@@ -140,5 +140,6 @@ extern struct intel_dvo_dev_ops ch7xxx_ops;
 extern struct intel_dvo_dev_ops ivch_ops;
 extern struct intel_dvo_dev_ops tfp410_ops;
 extern struct intel_dvo_dev_ops ch7017_ops;
+extern struct intel_dvo_dev_ops ns2501_ops;
 
 #endif /* _INTEL_DVO_H */
diff --git a/drivers/gpu/drm/i915/dvo_ns2501.c b/drivers/gpu/drm/i915/dvo_ns2501.c
new file mode 100644
index 00000000000..1a0bad9a5fa
--- /dev/null
+++ b/drivers/gpu/drm/i915/dvo_ns2501.c
@@ -0,0 +1,582 @@
+/*
+ *
+ * Copyright (c) 2012 Gilles Dartiguelongue, Thomas Richter
+ *
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#include "dvo.h"
+#include "i915_reg.h"
+#include "i915_drv.h"
+
+#define NS2501_VID 0x1305
+#define NS2501_DID 0x6726
+
+#define NS2501_VID_LO 0x00
+#define NS2501_VID_HI 0x01
+#define NS2501_DID_LO 0x02
+#define NS2501_DID_HI 0x03
+#define NS2501_REV 0x04
+#define NS2501_RSVD 0x05
+#define NS2501_FREQ_LO 0x06
+#define NS2501_FREQ_HI 0x07
+
+#define NS2501_REG8 0x08
+#define NS2501_8_VEN (1<<5)
+#define NS2501_8_HEN (1<<4)
+#define NS2501_8_DSEL (1<<3)
+#define NS2501_8_BPAS (1<<2)
+#define NS2501_8_RSVD (1<<1)
+#define NS2501_8_PD (1<<0)
+
+#define NS2501_REG9 0x09
+#define NS2501_9_VLOW (1<<7)
+#define NS2501_9_MSEL_MASK (0x7<<4)
+#define NS2501_9_TSEL (1<<3)
+#define NS2501_9_RSEN (1<<2)
+#define NS2501_9_RSVD (1<<1)
+#define NS2501_9_MDI (1<<0)
+
+#define NS2501_REGC 0x0c
+
+struct ns2501_priv {
+	//I2CDevRec d;
+	bool quiet;
+	int reg_8_shadow;
+	int reg_8_set;
+	// Shadow registers for i915
+	int dvoc;
+	int pll_a;
+	int srcdim;
+	int fw_blc;
+};
+
+#define NSPTR(d) ((NS2501Ptr)(d->DriverPrivate.ptr))
+
+/*
+ * Include the PLL launcher prototype
+ */
+extern void intel_enable_pll(struct drm_i915_private *dev_priv, enum pipe pipe);
+
+/*
+ * For reasons unclear to me, the ns2501 at least on the Fujitsu/Siemens
+ * laptops does not react on the i2c bus unless
+ * both the PLL is running and the display is configured in its native
+ * resolution.
+ * This function forces the DVO on, and stores the registers it touches.
+ * Afterwards, registers are restored to regular values.
+ *
+ * This is pretty much a hack, though it works.
+ * Without that, ns2501_readb and ns2501_writeb fail
+ * when switching the resolution.
+ */
+
+static void enable_dvo(struct intel_dvo_device *dvo)
+{
+	struct ns2501_priv *ns = (struct ns2501_priv *)(dvo->dev_priv);
+	struct i2c_adapter *adapter = dvo->i2c_bus;
+	struct intel_gmbus *bus = container_of(adapter,
+					       struct intel_gmbus,
+					       adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+
+	DRM_DEBUG_KMS("%s: Trying to re-enable the DVO\n", __FUNCTION__);
+
+	ns->dvoc = I915_READ(DVO_C);
+	ns->pll_a = I915_READ(_DPLL_A);
+	ns->srcdim = I915_READ(DVOC_SRCDIM);
+	ns->fw_blc = I915_READ(FW_BLC);
+
+	I915_WRITE(DVOC, 0x10004084);
+	I915_WRITE(_DPLL_A, 0xd0820000);
+	I915_WRITE(DVOC_SRCDIM, 0x400300);	// 1024x768
+	I915_WRITE(FW_BLC, 0x1080304);
+
+	intel_enable_pll(dev_priv, 0);
+
+	I915_WRITE(DVOC, 0x90004084);
+}
+
+/*
+ * Restore the I915 registers modified by the above
+ * trigger function.
+ */
+static void restore_dvo(struct intel_dvo_device *dvo)
+{
+	struct i2c_adapter *adapter = dvo->i2c_bus;
+	struct intel_gmbus *bus = container_of(adapter,
+					       struct intel_gmbus,
+					       adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+	struct ns2501_priv *ns = (struct ns2501_priv *)(dvo->dev_priv);
+
+	I915_WRITE(DVOC, ns->dvoc);
+	I915_WRITE(_DPLL_A, ns->pll_a);
+	I915_WRITE(DVOC_SRCDIM, ns->srcdim);
+	I915_WRITE(FW_BLC, ns->fw_blc);
+}
+
+/*
+** Read a register from the ns2501.
+** Returns true if successful, false otherwise.
+** If it returns false, it might be wise to enable the
+** DVO with the above function.
+*/
+static bool ns2501_readb(struct intel_dvo_device *dvo, int addr, uint8_t * ch)
+{
+	struct ns2501_priv *ns = dvo->dev_priv;
+	struct i2c_adapter *adapter = dvo->i2c_bus;
+	u8 out_buf[2];
+	u8 in_buf[2];
+
+	struct i2c_msg msgs[] = {
+		{
+		 .addr = dvo->slave_addr,
+		 .flags = 0,
+		 .len = 1,
+		 .buf = out_buf,
+		 },
+		{
+		 .addr = dvo->slave_addr,
+		 .flags = I2C_M_RD,
+		 .len = 1,
+		 .buf = in_buf,
+		 }
+	};
+
+	out_buf[0] = addr;
+	out_buf[1] = 0;
+
+	if (i2c_transfer(adapter, msgs, 2) == 2) {
+		*ch = in_buf[0];
+		return true;
+	};
+
+	if (!ns->quiet) {
+		DRM_DEBUG_KMS
+		    ("Unable to read register 0x%02x from %s:0x%02x.\n", addr,
+		     adapter->name, dvo->slave_addr);
+	}
+
+	return false;
+}
+
+/*
+** Write a register to the ns2501.
+** Returns true if successful, false otherwise.
+** If it returns false, it might be wise to enable the
+** DVO with the above function.
+*/
+static bool ns2501_writeb(struct intel_dvo_device *dvo, int addr, uint8_t ch)
+{
+	struct ns2501_priv *ns = dvo->dev_priv;
+	struct i2c_adapter *adapter = dvo->i2c_bus;
+	uint8_t out_buf[2];
+
+	struct i2c_msg msg = {
+		.addr = dvo->slave_addr,
+		.flags = 0,
+		.len = 2,
+		.buf = out_buf,
+	};
+
+	out_buf[0] = addr;
+	out_buf[1] = ch;
+
+	if (i2c_transfer(adapter, &msg, 1) == 1) {
+		return true;
+	}
+
+	if (!ns->quiet) {
+		DRM_DEBUG_KMS("Unable to write register 0x%02x to %s:%d\n",
+			      addr, adapter->name, dvo->slave_addr);
+	}
+
+	return false;
+}
+
+/* National Semiconductor 2501 driver for chip on i2c bus
+ * scan for the chip on the bus.
+ * Hope the VBIOS initialized the PLL correctly so we can
+ * talk to it. If not, it will not be seen and not detected.
+ * Bummer!
+ */
+static bool ns2501_init(struct intel_dvo_device *dvo,
+			struct i2c_adapter *adapter)
+{
+	/* this will detect the NS2501 chip on the specified i2c bus */
+	struct ns2501_priv *ns;
+	unsigned char ch;
+
+	ns = kzalloc(sizeof(struct ns2501_priv), GFP_KERNEL);
+	if (ns == NULL)
+		return false;
+
+	dvo->i2c_bus = adapter;
+	dvo->dev_priv = ns;
+	ns->quiet = true;
+
+	if (!ns2501_readb(dvo, NS2501_VID_LO, &ch))
+		goto out;
+
+	if (ch != (NS2501_VID & 0xff)) {
+		DRM_DEBUG_KMS("ns2501 not detected got %d: from %s Slave %d.\n",
+			      ch, adapter->name, dvo->slave_addr);
+		goto out;
+	}
+
+	if (!ns2501_readb(dvo, NS2501_DID_LO, &ch))
+		goto out;
+
+	if (ch != (NS2501_DID & 0xff)) {
+		DRM_DEBUG_KMS("ns2501 not detected got %d: from %s Slave %d.\n",
+			      ch, adapter->name, dvo->slave_addr);
+		goto out;
+	}
+	ns->quiet = false;
+	ns->reg_8_set = 0;
+	ns->reg_8_shadow =
+	    NS2501_8_PD | NS2501_8_BPAS | NS2501_8_VEN | NS2501_8_HEN;
+
+	DRM_DEBUG_KMS("init ns2501 dvo controller successfully!\n");
+	return true;
+
+out:
+	kfree(ns);
+	return false;
+}
+
+static enum drm_connector_status ns2501_detect(struct intel_dvo_device *dvo)
+{
+	/*
+	 * This is a Laptop display, it doesn't have hotplugging.
+	 * Even if not, the detection bit of the 2501 is unreliable as
+	 * it only works for some display types.
+	 * It is even more unreliable as the PLL must be active for
+	 * allowing reading from the chiop.
+	 */
+	return connector_status_connected;
+}
+
+static enum drm_mode_status ns2501_mode_valid(struct intel_dvo_device *dvo,
+					      struct drm_display_mode *mode)
+{
+	DRM_DEBUG_KMS
+	    ("%s: is mode valid (hdisplay=%d,htotal=%d,vdisplay=%d,vtotal=%d)\n",
+	     __FUNCTION__, mode->hdisplay, mode->htotal, mode->vdisplay,
+	     mode->vtotal);
+
+	/*
+	 * Currently, these are all the modes I have data from.
+	 * More might exist. Unclear how to find the native resolution
+	 * of the panel in here so we could always accept it
+	 * by disabling the scaler.
+	 */
+	if ((mode->hdisplay == 800 && mode->vdisplay == 600) ||
+	    (mode->hdisplay == 640 && mode->vdisplay == 480) ||
+	    (mode->hdisplay == 1024 && mode->vdisplay == 768)) {
+		return MODE_OK;
+	} else {
+		return MODE_ONE_SIZE;	/* Is this a reasonable error? */
+	}
+}
+
+static void ns2501_mode_set(struct intel_dvo_device *dvo,
+			    struct drm_display_mode *mode,
+			    struct drm_display_mode *adjusted_mode)
+{
+	bool ok;
+	bool restore = false;
+	struct ns2501_priv *ns = (struct ns2501_priv *)(dvo->dev_priv);
+
+	DRM_DEBUG_KMS
+	    ("%s: set mode (hdisplay=%d,htotal=%d,vdisplay=%d,vtotal=%d).\n",
+	     __FUNCTION__, mode->hdisplay, mode->htotal, mode->vdisplay,
+	     mode->vtotal);
+
+	/*
+	 * Where do I find the native resolution for which scaling is not required???
+	 *
+	 * First trigger the DVO on as otherwise the chip does not appear on the i2c
+	 * bus.
+	 */
+	do {
+		ok = true;
+
+		if (mode->hdisplay == 800 && mode->vdisplay == 600) {
+			/* mode 277 */
+			ns->reg_8_shadow &= ~NS2501_8_BPAS;
+			DRM_DEBUG_KMS("%s: switching to 800x600\n",
+				      __FUNCTION__);
+
+			/*
+			 * No, I do not know where this data comes from.
+			 * It is just what the video bios left in the DVO, so
+			 * I'm just copying it here over.
+			 * This also means that I cannot support any other modes
+			 * except the ones supported by the bios.
+			 */
+			ok &= ns2501_writeb(dvo, 0x11, 0xc8);	// 0xc7 also works.
+			ok &= ns2501_writeb(dvo, 0x1b, 0x19);
+			ok &= ns2501_writeb(dvo, 0x1c, 0x62);	// VBIOS left 0x64 here, but 0x62 works nicer
+			ok &= ns2501_writeb(dvo, 0x1d, 0x02);
+
+			ok &= ns2501_writeb(dvo, 0x34, 0x03);
+			ok &= ns2501_writeb(dvo, 0x35, 0xff);
+
+			ok &= ns2501_writeb(dvo, 0x80, 0x27);
+			ok &= ns2501_writeb(dvo, 0x81, 0x03);
+			ok &= ns2501_writeb(dvo, 0x82, 0x41);
+			ok &= ns2501_writeb(dvo, 0x83, 0x05);
+
+			ok &= ns2501_writeb(dvo, 0x8d, 0x02);
+			ok &= ns2501_writeb(dvo, 0x8e, 0x04);
+			ok &= ns2501_writeb(dvo, 0x8f, 0x00);
+
+			ok &= ns2501_writeb(dvo, 0x90, 0xfe);	/* vertical. VBIOS left 0xff here, but 0xfe works better */
+			ok &= ns2501_writeb(dvo, 0x91, 0x07);
+			ok &= ns2501_writeb(dvo, 0x94, 0x00);
+			ok &= ns2501_writeb(dvo, 0x95, 0x00);
+
+			ok &= ns2501_writeb(dvo, 0x96, 0x00);
+
+			ok &= ns2501_writeb(dvo, 0x99, 0x00);
+			ok &= ns2501_writeb(dvo, 0x9a, 0x88);
+
+			ok &= ns2501_writeb(dvo, 0x9c, 0x23);	/* Looks like first and last line of the image. */
+			ok &= ns2501_writeb(dvo, 0x9d, 0x00);
+			ok &= ns2501_writeb(dvo, 0x9e, 0x25);
+			ok &= ns2501_writeb(dvo, 0x9f, 0x03);
+
+			ok &= ns2501_writeb(dvo, 0xa4, 0x80);
+
+			ok &= ns2501_writeb(dvo, 0xb6, 0x00);
+
+			ok &= ns2501_writeb(dvo, 0xb9, 0xc8);	/* horizontal? */
+			ok &= ns2501_writeb(dvo, 0xba, 0x00);	/* horizontal? */
+
+			ok &= ns2501_writeb(dvo, 0xc0, 0x05);	/* horizontal? */
+			ok &= ns2501_writeb(dvo, 0xc1, 0xd7);
+
+			ok &= ns2501_writeb(dvo, 0xc2, 0x00);
+			ok &= ns2501_writeb(dvo, 0xc3, 0xf8);
+
+			ok &= ns2501_writeb(dvo, 0xc4, 0x03);
+			ok &= ns2501_writeb(dvo, 0xc5, 0x1a);
+
+			ok &= ns2501_writeb(dvo, 0xc6, 0x00);
+			ok &= ns2501_writeb(dvo, 0xc7, 0x73);
+			ok &= ns2501_writeb(dvo, 0xc8, 0x02);
+
+		} else if (mode->hdisplay == 640 && mode->vdisplay == 480) {
+			/* mode 274 */
+			DRM_DEBUG_KMS("%s: switching to 640x480\n",
+				      __FUNCTION__);
+			/*
+			 * No, I do not know where this data comes from.
+			 * It is just what the video bios left in the DVO, so
+			 * I'm just copying it here over.
+			 * This also means that I cannot support any other modes
+			 * except the ones supported by the bios.
+			 */
+			ns->reg_8_shadow &= ~NS2501_8_BPAS;
+
+			ok &= ns2501_writeb(dvo, 0x11, 0xa0);
+			ok &= ns2501_writeb(dvo, 0x1b, 0x11);
+			ok &= ns2501_writeb(dvo, 0x1c, 0x54);
+			ok &= ns2501_writeb(dvo, 0x1d, 0x03);
+
+			ok &= ns2501_writeb(dvo, 0x34, 0x03);
+			ok &= ns2501_writeb(dvo, 0x35, 0xff);
+
+			ok &= ns2501_writeb(dvo, 0x80, 0xff);
+			ok &= ns2501_writeb(dvo, 0x81, 0x07);
+			ok &= ns2501_writeb(dvo, 0x82, 0x3d);
+			ok &= ns2501_writeb(dvo, 0x83, 0x05);
+
+			ok &= ns2501_writeb(dvo, 0x8d, 0x02);
+			ok &= ns2501_writeb(dvo, 0x8e, 0x10);
+			ok &= ns2501_writeb(dvo, 0x8f, 0x00);
+
+			ok &= ns2501_writeb(dvo, 0x90, 0xff);	/* vertical */
+			ok &= ns2501_writeb(dvo, 0x91, 0x07);
+			ok &= ns2501_writeb(dvo, 0x94, 0x00);
+			ok &= ns2501_writeb(dvo, 0x95, 0x00);
+
+			ok &= ns2501_writeb(dvo, 0x96, 0x05);
+
+			ok &= ns2501_writeb(dvo, 0x99, 0x00);
+			ok &= ns2501_writeb(dvo, 0x9a, 0x88);
+
+			ok &= ns2501_writeb(dvo, 0x9c, 0x24);
+			ok &= ns2501_writeb(dvo, 0x9d, 0x00);
+			ok &= ns2501_writeb(dvo, 0x9e, 0x25);
+			ok &= ns2501_writeb(dvo, 0x9f, 0x03);
+
+			ok &= ns2501_writeb(dvo, 0xa4, 0x84);
+
+			ok &= ns2501_writeb(dvo, 0xb6, 0x09);
+
+			ok &= ns2501_writeb(dvo, 0xb9, 0xa0);	/* horizontal? */
+			ok &= ns2501_writeb(dvo, 0xba, 0x00);	/* horizontal? */
+
+			ok &= ns2501_writeb(dvo, 0xc0, 0x05);	/* horizontal? */
+			ok &= ns2501_writeb(dvo, 0xc1, 0x90);
+
+			ok &= ns2501_writeb(dvo, 0xc2, 0x00);
+			ok &= ns2501_writeb(dvo, 0xc3, 0x0f);
+
+			ok &= ns2501_writeb(dvo, 0xc4, 0x03);
+			ok &= ns2501_writeb(dvo, 0xc5, 0x16);
+
+			ok &= ns2501_writeb(dvo, 0xc6, 0x00);
+			ok &= ns2501_writeb(dvo, 0xc7, 0x02);
+			ok &= ns2501_writeb(dvo, 0xc8, 0x02);
+
+		} else if (mode->hdisplay == 1024 && mode->vdisplay == 768) {
+			/* mode 280 */
+			DRM_DEBUG_KMS("%s: switching to 1024x768\n",
+				      __FUNCTION__);
+			/*
+			 * This might or might not work, actually. I'm silently
+			 * assuming here that the native panel resolution is
+			 * 1024x768. If not, then this leaves the scaler disabled
+			 * generating a picture that is likely not the expected.
+			 *
+			 * Problem is that I do not know where to take the panel
+			 * dimensions from.
+			 *
+			 * Enable the bypass, scaling not required.
+			 *
+			 * The scaler registers are irrelevant here....
+			 *
+			 */
+			ns->reg_8_shadow |= NS2501_8_BPAS;
+			ok &= ns2501_writeb(dvo, 0x37, 0x44);
+		} else {
+			/*
+			 * Data not known. Bummer!
+			 * Hopefully, the code should not go here
+			 * as mode_OK delivered no other modes.
+			 */
+			ns->reg_8_shadow |= NS2501_8_BPAS;
+		}
+		ok &= ns2501_writeb(dvo, NS2501_REG8, ns->reg_8_shadow);
+
+		if (!ok) {
+			if (restore)
+				restore_dvo(dvo);
+			enable_dvo(dvo);
+			restore = true;
+		}
+	} while (!ok);
+	/*
+	 * Restore the old i915 registers before
+	 * forcing the ns2501 on.
+	 */
+	if (restore)
+		restore_dvo(dvo);
+}
+
+/* set the NS2501 power state */
+static void ns2501_dpms(struct intel_dvo_device *dvo, int mode)
+{
+	bool ok;
+	bool restore = false;
+	struct ns2501_priv *ns = (struct ns2501_priv *)(dvo->dev_priv);
+	unsigned char ch;
+
+	DRM_DEBUG_KMS("%s: Trying set the dpms of the DVO to %d\n",
+		      __FUNCTION__, mode);
+
+	ch = ns->reg_8_shadow;
+
+	if (mode == DRM_MODE_DPMS_ON)
+		ch |= NS2501_8_PD;
+	else
+		ch &= ~NS2501_8_PD;
+
+	if (ns->reg_8_set == 0 || ns->reg_8_shadow != ch) {
+		ns->reg_8_set = 1;
+		ns->reg_8_shadow = ch;
+
+		do {
+			ok = true;
+			ok &= ns2501_writeb(dvo, NS2501_REG8, ch);
+			ok &=
+			    ns2501_writeb(dvo, 0x34,
+					  (mode ==
+					   DRM_MODE_DPMS_ON) ? (0x03) : (0x00));
+			ok &=
+			    ns2501_writeb(dvo, 0x35,
+					  (mode ==
+					   DRM_MODE_DPMS_ON) ? (0xff) : (0x00));
+			if (!ok) {
+				if (restore)
+					restore_dvo(dvo);
+				enable_dvo(dvo);
+				restore = true;
+			}
+		} while (!ok);
+
+		if (restore)
+			restore_dvo(dvo);
+	}
+}
+
+static void ns2501_dump_regs(struct intel_dvo_device *dvo)
+{
+	uint8_t val;
+
+	ns2501_readb(dvo, NS2501_FREQ_LO, &val);
+	DRM_LOG_KMS("NS2501_FREQ_LO: 0x%02x\n", val);
+	ns2501_readb(dvo, NS2501_FREQ_HI, &val);
+	DRM_LOG_KMS("NS2501_FREQ_HI: 0x%02x\n", val);
+	ns2501_readb(dvo, NS2501_REG8, &val);
+	DRM_LOG_KMS("NS2501_REG8: 0x%02x\n", val);
+	ns2501_readb(dvo, NS2501_REG9, &val);
+	DRM_LOG_KMS("NS2501_REG9: 0x%02x\n", val);
+	ns2501_readb(dvo, NS2501_REGC, &val);
+	DRM_LOG_KMS("NS2501_REGC: 0x%02x\n", val);
+}
+
+static void ns2501_destroy(struct intel_dvo_device *dvo)
+{
+	struct ns2501_priv *ns = dvo->dev_priv;
+
+	if (ns) {
+		kfree(ns);
+		dvo->dev_priv = NULL;
+	}
+}
+
+struct intel_dvo_dev_ops ns2501_ops = {
+	.init = ns2501_init,
+	.detect = ns2501_detect,
+	.mode_valid = ns2501_mode_valid,
+	.mode_set = ns2501_mode_set,
+	.dpms = ns2501_dpms,
+	.dump_regs = ns2501_dump_regs,
+	.destroy = ns2501_destroy,
+};
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f8c2aa1ec27..93d9934ba32 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1428,8 +1428,10 @@ static void assert_pch_ports_disabled(struct drm_i915_private *dev_priv,
  * protect mechanism may be enabled.
  *
  * Note!  This is for pre-ILK only.
+ *
+ * Unfortunately needed by dvo_ns2501 since the dvo depends on it running.
  */
-static void intel_enable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
+void intel_enable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
 {
 	int reg;
 	u32 val;
diff --git a/drivers/gpu/drm/i915/intel_dvo.c b/drivers/gpu/drm/i915/intel_dvo.c
index 556cf6bf2a5..03dfdff8e00 100644
--- a/drivers/gpu/drm/i915/intel_dvo.c
+++ b/drivers/gpu/drm/i915/intel_dvo.c
@@ -37,6 +37,7 @@
 #define SIL164_ADDR	0x38
 #define CH7xxx_ADDR	0x76
 #define TFP410_ADDR	0x38
+#define NS2501_ADDR     0x38
 
 static const struct intel_dvo_device intel_dvo_devices[] = {
 	{
@@ -74,7 +75,14 @@ static const struct intel_dvo_device intel_dvo_devices[] = {
 		.slave_addr = 0x75,
 		.gpio = GMBUS_PORT_DPB,
 		.dev_ops = &ch7017_ops,
-	}
+	},
+	{
+	        .type = INTEL_DVO_CHIP_TMDS,
+		.name = "ns2501",
+		.dvo_reg = DVOC,
+		.slave_addr = NS2501_ADDR,
+		.dev_ops = &ns2501_ops,
+       }
 };
 
 struct intel_dvo {