[Intel-gfx] [PATCH] drm/i915: unconditionally unlock panel regs

[Jesse Barnes]

In the panel_on function we skip everything if the panel is already
powered up.  However, if it's powered up but not unlocked, subsequent
register writes may fail.

So unlock the regs regardless of the panel state to allow other mode
setting programming to occur normally.

[Still waiting to hear from bug reporters & testers on this one, but
it does get my Vaio working again, with or without the eDP VBT patch
reverted.]

Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index f74a706..129d47a 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -818,6 +818,11 @@ static bool ironlake_edp_panel_on (struct intel_dp *intel_dp)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 pp, idle_on_mask = PP_ON | PP_SEQUENCE_STATE_ON_IDLE;
 
+	pp = I915_READ(PCH_PP_CONTROL);
+	pp |= PANEL_UNLOCK_REGS | POWER_TARGET_ON;
+	I915_WRITE(PCH_PP_CONTROL, pp);
+	POSTING_READ(PCH_PP_CONTROL);
+
 	if (I915_READ(PCH_PP_STATUS) & PP_ON)
 		return true;