[ 3.5.y.z extended stable ] Patch "drm/i915: add some barriers when changing DIPs" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    drm/i915: add some barriers when changing DIPs

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 1a5b25b73cd2032b219c3e6a8e7e5f64b81edac5 Mon Sep 17 00:00:00 2001
From: Paulo Zanoni <paulo.r.zanoni at intel.com>
Date: Mon, 28 May 2012 16:43:00 -0300
Subject: [PATCH] drm/i915: add some barriers when changing DIPs

commit 9d9740f099f2eaf309c4c9cbc0d732507140db28 upstream.

On IVB and older, we basically have two registers: the control and the
data register. We write a few consecutitve times to the control
register, and we need these writes to arrive exactly in the specified
order.

Also, when we're changing the data register, we need to guarantee that
anything written to the control register already arrived (since
changing the control register can change where the data register
points to). Also, we need to make sure all the writes to the data
register happen exactly in the specified order, and we also *can't*
read the data register during this process, since reading and/or
writing it will change the place it points to.

So invoke the "better safe than sorry" rule and just be careful and
put barriers everywhere :)

On HSW we still have a control register that we write many times, but
we have many data registers.

Demanded-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
[ herton: drop changes to *_set_infoframes functions, not present in
  3.5. While commits which add *_set_infoframes and all that could be
  picked, may be it's too much for this stable (although they fix other
  issues), just this makes next patch easier to apply ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/gpu/drm/i915/intel_hdmi.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index bc1f0f2..a0194e5 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -141,16 +141,19 @@ static void g4x_write_infoframe(struct drm_encoder *encoder,

 	I915_WRITE(VIDEO_DIP_CTL, val);

+	mmiowb();
 	for (i = 0; i < len; i += 4) {
 		I915_WRITE(VIDEO_DIP_DATA, *data);
 		data++;
 	}
+	mmiowb();

 	val |= g4x_infoframe_enable(frame);
 	val &= ~VIDEO_DIP_FREQ_MASK;
 	val |= VIDEO_DIP_FREQ_VSYNC;

 	I915_WRITE(VIDEO_DIP_CTL, val);
+	POSTING_READ(VIDEO_DIP_CTL);
 }

 static void ibx_write_infoframe(struct drm_encoder *encoder,
@@ -190,16 +193,19 @@ static void ibx_write_infoframe(struct drm_encoder *encoder,

 	I915_WRITE(reg, val);

+	mmiowb();
 	for (i = 0; i < len; i += 4) {
 		I915_WRITE(TVIDEO_DIP_DATA(intel_crtc->pipe), *data);
 		data++;
 	}
+	mmiowb();

 	val |= g4x_infoframe_enable(frame);
 	val &= ~VIDEO_DIP_FREQ_MASK;
 	val |= VIDEO_DIP_FREQ_VSYNC;

 	I915_WRITE(reg, val);
+	POSTING_READ(reg);
 }

 static void cpt_write_infoframe(struct drm_encoder *encoder,
@@ -229,16 +235,19 @@ static void cpt_write_infoframe(struct drm_encoder *encoder,

 	I915_WRITE(reg, val);

+	mmiowb();
 	for (i = 0; i < len; i += 4) {
 		I915_WRITE(TVIDEO_DIP_DATA(intel_crtc->pipe), *data);
 		data++;
 	}
+	mmiowb();

 	val |= g4x_infoframe_enable(frame);
 	val &= ~VIDEO_DIP_FREQ_MASK;
 	val |= VIDEO_DIP_FREQ_VSYNC;

 	I915_WRITE(reg, val);
+	POSTING_READ(reg);
 }

 static void vlv_write_infoframe(struct drm_encoder *encoder,
@@ -262,16 +271,19 @@ static void vlv_write_infoframe(struct drm_encoder *encoder,

 	I915_WRITE(reg, val);

+	mmiowb();
 	for (i = 0; i < len; i += 4) {
 		I915_WRITE(VLV_TVIDEO_DIP_DATA(intel_crtc->pipe), *data);
 		data++;
 	}
+	mmiowb();

 	val |= g4x_infoframe_enable(frame);
 	val &= ~VIDEO_DIP_FREQ_MASK;
 	val |= VIDEO_DIP_FREQ_VSYNC;

 	I915_WRITE(reg, val);
+	POSTING_READ(reg);
 }

 static void hsw_write_infoframe(struct drm_encoder *encoder,
@@ -294,13 +306,16 @@ static void hsw_write_infoframe(struct drm_encoder *encoder,
 	val &= ~hsw_infoframe_enable(frame);
 	I915_WRITE(ctl_reg, val);

+	mmiowb();
 	for (i = 0; i < len; i += 4) {
 		I915_WRITE(data_reg + i, *data);
 		data++;
 	}
+	mmiowb();

 	val |= hsw_infoframe_enable(frame);
 	I915_WRITE(ctl_reg, val);
+	POSTING_READ(ctl_reg);
 }

 static void intel_set_infoframe(struct drm_encoder *encoder,
--
1.7.9.5