From cdb0e95bf571dccc1f75fef9bdad21b167ef0b37 Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Tue, 1 Nov 2011 20:00:06 -0700 Subject: [PATCH] drm/i915: Try harder during dp pattern 1 link training Instead of going through the sequence just once, run through the whole set up to 5 times to see if something can work. This isn't part of the DP spec, but the BIOS seems to do it, and given that link training failure is so bad, it seems reasonable to follow suit. Signed-off-by: Keith Packard Reviewed-by: Jesse Barnes --- drivers/gpu/drm/i915/intel_dp.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 8e37fdd1fa2f..7101b8b4f8b4 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -1581,7 +1581,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp) int i; uint8_t voltage; bool clock_recovery = false; - int tries; + int voltage_tries, loop_tries; u32 reg; uint32_t DP = intel_dp->DP; @@ -1608,7 +1608,8 @@ intel_dp_start_link_train(struct intel_dp *intel_dp) DP &= ~DP_LINK_TRAIN_MASK; memset(intel_dp->train_set, 0, 4); voltage = 0xff; - tries = 0; + voltage_tries = 0; + loop_tries = 0; clock_recovery = false; for (;;) { /* Use intel_dp->train_set[0] to set the voltage and pre emphasis values */ @@ -1651,16 +1652,26 @@ intel_dp_start_link_train(struct intel_dp *intel_dp) for (i = 0; i < intel_dp->lane_count; i++) if ((intel_dp->train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0) break; - if (i == intel_dp->lane_count) - break; + if (i == intel_dp->lane_count) { + ++loop_tries; + if (loop_tries == 5) { + DRM_DEBUG_KMS("too many full retries, give up\n"); + break; + } + memset(intel_dp->train_set, 0, 4); + voltage_tries = 0; + continue; + } /* Check to see if we've tried the same voltage 5 times */ if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) == voltage) { - ++tries; - if (tries == 5) + ++voltage_tries; + if (voltage_tries == 5) { + DRM_DEBUG_KMS("too many voltage retries, give up\n"); break; + } } else - tries = 0; + voltage_tries = 0; voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK; /* Compute new intel_dp->train_set as requested by target */ -- GitLab