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Revert "drm/i915: Try harder to complete DP training pattern 1" 

This reverts commit 2477367083.

If (for whatever reason) the DP sink device never asks for the maximal
voltage level, we never don't hit the check that should bail us out
after 5 retries of the same voltage. Which leads to an endless loop in
the DP link training code, which hangs the driver.

Now some more DP link training experiments on eDP panels seem to
indicate that our training algorithm isn't robust enough anyway and
needs more work. Hence for 3.7-fixes, let's just revert the regressing
commit instead of trying to apply more duct-tape.

Reported-by: Oleksij Rempel <bug-track@fisher-privat.net>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2012-10-16 09:50:25 +02:00
parent e751823da2
commit b06fbda328
1 changed files with 10 additions and 5 deletions
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15
drivers/gpu/drm/i915/intel_dp.c
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@ -1798,7 +1798,8 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
if ((intel_dp->train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0)
break;
if (i == intel_dp->lane_count && voltage_tries == 5) {
if (++loop_tries == 5) {
++loop_tries;
if (loop_tries == 5) {
DRM_DEBUG_KMS("too many full retries, give up\n");
break;
}
@ -1808,11 +1809,15 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
}
/* Check to see if we've tried the same voltage 5 times */
if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) != voltage) {
voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
voltage_tries = 0;
} else
if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) == voltage) {
++voltage_tries;
if (voltage_tries == 5) {
DRM_DEBUG_KMS("too many voltage retries, give up\n");
break;
}
} else
voltage_tries = 0;
voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
/* Compute new intel_dp->train_set as requested by target */
intel_get_adjust_train(intel_dp, link_status);