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* [PATCH] drm/i915/hsw: Fix workaround for server AUX channel clock divisor
@ 2015-05-19 16:13 jim.bride
  2015-05-20 23:07 ` Todd Previte
  0 siblings, 1 reply; 6+ messages in thread
From: jim.bride @ 2015-05-19 16:13 UTC (permalink / raw)
  To: intel-gfx

From: Jim Bride <jim.bride@linux.intel.com>

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.

Signed-off-by: Jim Bride <jim.bride@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 0edc305..c01a3f9 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -895,7 +895,8 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
 			if (status & DP_AUX_CH_CTL_DONE)
 				break;
 		}
-		if (status & DP_AUX_CH_CTL_DONE)
+		if ((status & DP_AUX_CH_CTL_DONE) &&
+		    !(status & DP_AUX_CH_CTL_TIME_OUT_ERROR))
 			break;
 	}
 
-- 
1.9.1

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^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2015-05-22  4:44 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-05-19 16:13 [PATCH] drm/i915/hsw: Fix workaround for server AUX channel clock divisor jim.bride
2015-05-20 23:07 ` Todd Previte
2015-05-21  8:20   ` Ville Syrjälä
2015-05-21 12:04     ` Jani Nikula
2015-05-21 18:34       ` Jim Bride
2015-05-22  4:43         ` Jani Nikula

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