This is a note to let you know that I've just added the patch titled
drm/i915/dp: Be paranoid in case we disable a DP before it is attached
to the 2.6.38-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-i915-dp-be-paranoid-in-case-we-disable-a-dp-before-it-is-attached.patch
and it can be found in the queue-2.6.38 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 31acbcc408f412d1ba73765b846c38642be553c3 Mon Sep 17 00:00:00 2001
From: Chris Wilson <[email protected]>
Date: Sun, 17 Apr 2011 06:38:35 +0100
Subject: drm/i915/dp: Be paranoid in case we disable a DP before it is attached
From: Chris Wilson <[email protected]>
commit 31acbcc408f412d1ba73765b846c38642be553c3 upstream.
Given that the hardware may be left in a random condition by the BIOS,
it is conceivable that we then attempt to clear the DP_PIPEB_SELECT bit
without us ever enabling/attaching the DP encoder to a pipe. Thus
causing a NULL deference when we attempt to wait for a vblank on that
crtc.
Reported-and-tested-by: Bryan Christ <[email protected]>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=36314
Signed-off-by: Chris Wilson <[email protected]>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=36456
Reported-and-tested-by: Bo Wang <[email protected]>
Signed-off-by: Keith Packard <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/gpu/drm/i915/intel_dp.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1455,7 +1455,8 @@ intel_dp_link_down(struct intel_dp *inte
if (!HAS_PCH_CPT(dev) &&
I915_READ(intel_dp->output_reg) & DP_PIPEB_SELECT) {
- struct intel_crtc *intel_crtc =
to_intel_crtc(intel_dp->base.base.crtc);
+ struct drm_crtc *crtc = intel_dp->base.base.crtc;
+
/* Hardware workaround: leaving our transcoder select
* set to transcoder B while it's off will prevent the
* corresponding HDMI output on transcoder A.
@@ -1470,7 +1471,19 @@ intel_dp_link_down(struct intel_dp *inte
/* Changes to enable or select take place the vblank
* after being written.
*/
- intel_wait_for_vblank(dev, intel_crtc->pipe);
+ if (crtc == NULL) {
+ /* We can arrive here never having been attached
+ * to a CRTC, for instance, due to inheriting
+ * random state from the BIOS.
+ *
+ * If the pipe is not running, play safe and
+ * wait for the clocks to stabilise before
+ * continuing.
+ */
+ POSTING_READ(intel_dp->output_reg);
+ msleep(50);
+ } else
+ intel_wait_for_vblank(dev, to_intel_crtc(crtc)->pipe);
}
I915_WRITE(intel_dp->output_reg, DP & ~DP_PORT_EN);
Patches currently in stable-queue which might be from [email protected]
are
queue-2.6.38/drm-i915-release-object-along-create-user-fb-error-path.patch
queue-2.6.38/drm-i915-lvds-only-act-on-lid-notify-when-the-device-is-on.patch
queue-2.6.38/drm-i915-dp-be-paranoid-in-case-we-disable-a-dp-before-it-is-attached.patch
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