This is a note to let you know that I've just added the patch titled
drm/i915/hsw: Fix workaround for server AUX channel clock divisor
to the 3.14-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-hsw-fix-workaround-for-server-aux-channel-clock-divisor.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e058c945e03a629c99606452a6931f632dd28903 Mon Sep 17 00:00:00 2001
From: Jim Bride <jim.bride@xxxxxxxxxxxxxxx>
Date: Wed, 27 May 2015 10:21:48 -0700
Subject: drm/i915/hsw: Fix workaround for server AUX channel clock divisor
From: Jim Bride <jim.bride@xxxxxxxxxxxxxxx>
commit e058c945e03a629c99606452a6931f632dd28903 upstream.
According to the HSW b-spec we need to try clock divisors of 63
and 72, each 3 or more times, when attempting DP AUX channel
communication on a server chipset. This actually wasn't happening
due to a short-circuit that only checked the DP_AUX_CH_CTL_DONE bit
in status rather than checking that the operation was done and
that DP_AUX_CH_CTL_TIME_OUT_ERROR was not set.
[v2] Implemented alternate solution suggested by Jani Nikula.
Signed-off-by: Jim Bride <jim.bride@xxxxxxxxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -481,10 +481,8 @@ intel_dp_aux_ch(struct intel_dp *intel_d
DP_AUX_CH_CTL_RECEIVE_ERROR))
continue;
if (status & DP_AUX_CH_CTL_DONE)
- break;
+ goto done;
}
- if (status & DP_AUX_CH_CTL_DONE)
- break;
}
if ((status & DP_AUX_CH_CTL_DONE) == 0) {
@@ -493,6 +491,7 @@ intel_dp_aux_ch(struct intel_dp *intel_d
goto out;
}
+done:
/* Check for timeout or receive error.
* Timeouts occur when the sink is not connected
*/
Patches currently in stable-queue which might be from jim.bride@xxxxxxxxxxxxxxx are
queue-3.14/drm-i915-hsw-fix-workaround-for-server-aux-channel-clock-divisor.patch
queue-3.14/drm-i915-fix-ddc-probe-for-passive-adapters.patch
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