[LUCID SRU] request pull i915: fix ironlake edp panel setup (v4)

[Manoj Iyer]

BUG
===
http://launchpad.net/bugs/561802

SRU JUSTIFICATION
================
During installation, bootup (plymouth) and while inside X, screen remains 
blank. Switching VTs yields no results (screen remains blank). This patch 
is required to fix this issue.

TESTING
=======
The patch was tested by James Ferguson @ canonical on E6510 and E6410 and 
reported to work. It does introduce any regressions on other systems I 
tested.

PATCH
=====
The patch is not readily application from upstream to Lucid, it needs to 
be back ported. I have already submitted the patch to stable at kernel.org for 
stable inclusion 3.6.34.y.

The following changes since commit 
f093f69b09ba908509e031d9578e92b2ce8d3582:
   Adam Jackson (1):
         drm/i915: Make G4X-style PLL search more permissive

are available in the git repository at:


git://kernel.ubuntu.com/git/manjo/ubuntu-lucid.git lp561802

Dave Airlie (1):
       i915: fix ironlake edp panel setup (v4)

  drivers/gpu/drm/i915/intel_dp.c |   27 ++++++++++++++++++++++++---
  1 files changed, 24 insertions(+), 3 deletions(-)

>From 39d72c68727400af464103d209fe0dcba832b21f Mon Sep 17 00:00:00 2001
From: Dave Airlie <airlied at redhat.com>
Date: Wed, 30 Jun 2010 11:46:17 +1000
Subject: [PATCH] i915: fix ironlake edp panel setup (v4)

The eDP spec claims a 20% overhead for the 8:10 encoding scheme used
on the wire. Take this into account when picking the lane/clock speed
for the panel.

v3: some panels are out of spec, try our best to deal with them, don't
refuse modes on eDP panels, and try the largest allowed settings if
all else fails on eDP.
v4: fix stupid typo, forgot to git add before amending.

Fixes several reports in bugzilla:

       https://bugs.freedesktop.org/show_bug.cgi?id=28070

Signed-off-by: Dave Airlie <airlied at redhat.com>
Signed-off-by: Eric Anholt <eric at anholt.net>
Signed-off-by: Manoj Iyer <manoj.iyer at canonical.com>

Buglink: http://launchpad.net/bugs/561802

This patch is backported from upstream patch SHAID: fe27d53e5c597ee5ba5d72a29d517091f244e974
---
  drivers/gpu/drm/i915/intel_dp.c |   27 ++++++++++++++++++++++++---
  1 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 6b62762..63ea21e 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -137,6 +137,12 @@ intel_dp_link_required(struct drm_device *dev,
  }

  static int
+intel_dp_max_data_rate(int max_link_clock, int max_lanes)
+{
+	return (max_link_clock * max_lanes * 8) / 10;
+}
+
+static int
  intel_dp_mode_valid(struct drm_connector *connector,
  		    struct drm_display_mode *mode)
  {
@@ -144,8 +150,11 @@ intel_dp_mode_valid(struct drm_connector *connector,
  	int max_link_clock = intel_dp_link_clock(intel_dp_max_link_bw(intel_output));
  	int max_lanes = intel_dp_max_lane_count(intel_output);

-	if (intel_dp_link_required(connector->dev, intel_output, mode->clock)
-			> max_link_clock * max_lanes)
+	/* only refuse the mode on non eDP since we have seen some wierd eDP panels
+	   which are outside spec tolerances but somehow work by magic */
+	if (!IS_eDP(intel_output) &&
+	    (intel_dp_link_required(connector->dev, intel_output, mode->clock)
+	     > intel_dp_max_data_rate(max_link_clock, max_lanes)))
  		return MODE_CLOCK_HIGH;

  	if (mode->clock < 10000)
@@ -497,7 +506,7 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,

  	for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) {
  		for (clock = 0; clock <= max_clock; clock++) {
-			int link_avail = intel_dp_link_clock(bws[clock]) * lane_count;
+			int link_avail = intel_dp_max_data_rate(intel_dp_link_clock(bws[clock]), lane_count);

  			if (intel_dp_link_required(encoder->dev, intel_output, mode->clock)
  					<= link_avail) {
@@ -512,6 +521,18 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,
  			}
  		}
  	}
+
+	if (IS_eDP(intel_output)) {
+		/* okay we failed just pick the highest */
+		dp_priv->lane_count = max_lane_count;
+		dp_priv->link_bw = bws[max_clock];
+		adjusted_mode->clock = intel_dp_link_clock(dp_priv->link_bw);
+		DRM_DEBUG_KMS("Force picking display port link bw %02x lane "
+			      "count %d clock %d\n",
+			      dp_priv->link_bw, dp_priv->lane_count,
+			      adjusted_mode->clock);
+		return true;
+	}
  	return false;
  }

-- 
1.7.0.4



Cheers
--- manjo