Commit e058c945 authored by Jim Bride's avatar Jim Bride Committed by Jani Nikula

drm/i915/hsw: Fix workaround for server AUX channel clock divisor

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.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarJim Bride <jim.bride@linux.intel.com>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
parent c65b99f0
...@@ -880,10 +880,8 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, ...@@ -880,10 +880,8 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
DP_AUX_CH_CTL_RECEIVE_ERROR)) DP_AUX_CH_CTL_RECEIVE_ERROR))
continue; continue;
if (status & DP_AUX_CH_CTL_DONE) 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) { if ((status & DP_AUX_CH_CTL_DONE) == 0) {
...@@ -892,6 +890,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, ...@@ -892,6 +890,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
goto out; goto out;
} }
done:
/* Check for timeout or receive error. /* Check for timeout or receive error.
* Timeouts occur when the sink is not connected * Timeouts occur when the sink is not connected
*/ */
......
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