Bug#658662: drm/i915: no signal via DisplayPort on Sandy Bridge since Linux 3.2
tags 658662 = upstream patch
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Peter Colberg wrote:
> On Wed, Jul 04, 2012 at 10:39:49AM -0500, Jonathan Nieder wrote:
>> From: Jesse Barnes <jbarnes@virtuousgeek.org>
>> Date: Thu, 21 Jun 2012 15:13:50 -0700
>> Subject: drm/i915: prefer wide & slow to fast & narrow in DP configs
[...]
> I tested upstream linux 3.2.23 with the above patch applied, and
> the display is working fine, i.e. it comes up in maximum, native
> resolution even after power-cycling the display.
Nice to hear.
The patch is in linux-next but still not in Linus's tree, so I guess
we'll have to wait before this can be applied to the 3.2.y tree.
Kernel team: please consider the attached patch for wheezy in the
meantime.
Thanks,
Jonathan
Index: debian/patches/bugfix/x86/drm-i915-prefer-wide-slow-to-fast-narrow-in-DP-confi.patch
===================================================================
--- debian/patches/bugfix/x86/drm-i915-prefer-wide-slow-to-fast-narrow-in-DP-confi.patch (revision 0)
+++ debian/patches/bugfix/x86/drm-i915-prefer-wide-slow-to-fast-narrow-in-DP-confi.patch (working copy)
@@ -0,0 +1,39 @@
+From: Jesse Barnes <jbarnes@virtuousgeek.org>
+Date: Thu, 21 Jun 2012 15:13:50 -0700
+Subject: drm/i915: prefer wide & slow to fast & narrow in DP configs
+
+commit 2514bc510d0c3aadcc5204056bb440fa36845147 upstream.
+
+High frequency link configurations have the potential to cause trouble
+with long and/or cheap cables, so prefer slow and wide configurations
+instead. This patch has the potential to cause trouble for eDP
+configurations that lie about available lanes, so if we run into that we
+can make it conditional on eDP.
+
+Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=45801
+Tested-by: peter@colberg.org
+Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
+Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
+Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
+---
+ drivers/gpu/drm/i915/intel_dp.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
+index d4c4937067fb..fae2050324bc 100644
+--- a/drivers/gpu/drm/i915/intel_dp.c
++++ b/drivers/gpu/drm/i915/intel_dp.c
+@@ -708,8 +708,8 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,
+
+ bpp = adjusted_mode->private_flags & INTEL_MODE_DP_FORCE_6BPC ? 18 : 24;
+
+- for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) {
+- for (clock = 0; clock <= max_clock; clock++) {
++ for (clock = 0; clock <= max_clock; clock++) {
++ for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) {
+ int link_avail = intel_dp_max_data_rate(intel_dp_link_clock(bws[clock]), lane_count);
+
+ if (intel_dp_link_required(mode->clock, bpp)
+--
+1.7.10.4
+
Index: debian/patches/series
===================================================================
--- debian/patches/series (revision 19261)
+++ debian/patches/series (working copy)
@@ -379,3 +379,5 @@
features/all/fermi-accel/drm-nouveau-oops-increase-channel-dispc_vma-to-4.patch
features/all/fermi-accel/drm-nvd0-disp-ignore-clock-set-if-no-pclk.patch
features/all/fermi-accel/drm-nouveau-bump-version-to-1.0.0.patch
+
+bugfix/x86/drm-i915-prefer-wide-slow-to-fast-narrow-in-DP-confi.patch
Index: debian/changelog
===================================================================
--- debian/changelog (revision 19261)
+++ debian/changelog (working copy)
@@ -38,6 +38,10 @@
- Refactor sub-channel use
- Bump version to 1.0.0
+ [ Jonathan Nieder ]
+ * [x86] drm/i915: prefer wide & slow to fast & narrow in DP configs
+ (Closes: #658662)
+
-- Ben Hutchings <ben@decadent.org.uk> Fri, 29 Jun 2012 15:01:22 +0100
linux (3.2.21-3) unstable; urgency=low
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