This is a note to let you know that I've just added the patch titled
Revert "drm/i915/dp: Use auxch precharge value of 5 everywhere"
to the 3.4-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:
revert-drm-i915-dp-use-auxch-precharge-value-of-5-everywhere.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 6b4e0a93ff6e45714c72bdce193f719ed94810e3 Mon Sep 17 00:00:00 2001
From: Daniel Vetter <[email protected]>
Date: Thu, 14 Jun 2012 22:15:00 +0200
Subject: Revert "drm/i915/dp: Use auxch precharge value of 5 everywhere"
From: Daniel Vetter <[email protected]>
commit 6b4e0a93ff6e45714c72bdce193f719ed94810e3 upstream.
This reverts commit 092945e11c5b84f66dd08f0b87fb729715d377bc.
This commit prevents a DP screen from properly training the link.
Oddly enough it works, once the machine has been warm-booted with an
older kernel.
According to DP docs this _should_ have been the right precharge time.
Also, the commit that originally introduces this was just general snb
DP enabling and didn't mention any specific reason for this special
value. Whatever, trust the reporter that this makes things worse and
let's just revert it.
v2: Less spelling fail.
Cc: Adam Jackson <[email protected]>
Cc: Jesse Barnes <[email protected]>
Reported-by: "Wouter M. Koolen" <[email protected]>
Buglink: https://lkml.org/lkml/2012/6/14/301
Signed-Off-by: Daniel Vetter <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/gpu/drm/i915/intel_dp.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -368,7 +368,7 @@ intel_dp_aux_ch(struct intel_dp *intel_d
int recv_bytes;
uint32_t status;
uint32_t aux_clock_divider;
- int try, precharge = 5;
+ int try, precharge;
intel_dp_check_edp(intel_dp);
/* The clock divider is based off the hrawclk,
@@ -388,6 +388,11 @@ intel_dp_aux_ch(struct intel_dp *intel_d
else
aux_clock_divider = intel_hrawclk(dev) / 2;
+ if (IS_GEN6(dev))
+ precharge = 3;
+ else
+ precharge = 5;
+
/* Try to wait for any previous AUX channel activity */
for (try = 0; try < 3; try++) {
status = I915_READ(ch_ctl);
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/drm-sis-initialize-object_idr.patch
queue-3.4/drm-via-initialize-object_idr.patch
queue-3.4/revert-drm-i915-dp-use-auxch-precharge-value-of-5-everywhere.patch
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