[Intel-gfx] [PATCH] drm/i915: vlv: fix DP PHY lockup due to invalid PP sequencer setup

[Imre Deak]

Atm we setup the HW panel power sequencer logic both for eDP and DP
ports. On eDP we then go on and start the power on sequence and commence
with link training when it's ready. On DP we don't do the power on
sequencing but do the link training immediately. At this point the DP
PHY block gets stuck, since - supposedly - it is waiting for the power
on sequence to finish. The actual register write that seems to hold off
the PHY is PIPEX_PP_ON_DELAYS[Panel Control Port Select]. Writing here
a non-0 value eventually sets PIPEX_PP_STATUS[Require Asset Status] to
1 and blocks the PHY until the panel power on is ready.

Fix this by not doing any PP sequencing setup for DP ports.

Thanks to Ville Syrjälä, Jesse Barnes and Todd Previte for the help in
tracking this down.

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ffac7e8..b744073 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1933,10 +1933,12 @@ static void vlv_pre_enable_dp(struct intel_encoder *encoder)
 
 	mutex_unlock(&dev_priv->dpio_lock);
 
-	/* init power sequencer on this pipe and port */
-	intel_dp_init_panel_power_sequencer(dev, intel_dp, &power_seq);
-	intel_dp_init_panel_power_sequencer_registers(dev, intel_dp,
-						      &power_seq);
+	if (is_edp(intel_dp)) {
+		/* init power sequencer on this pipe and port */
+		intel_dp_init_panel_power_sequencer(dev, intel_dp, &power_seq);
+		intel_dp_init_panel_power_sequencer_registers(dev, intel_dp,
+							      &power_seq);
+	}
 
 	intel_enable_dp(encoder);
 
-- 
1.8.4