[Intel-gfx] [PATCH] drm/i915: Cancel vdd off work before suspend

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Currently we just make sure vdd is off before suspending, but we don't
cancel the vdd off work. The work wil not touch vdd if
want_panel_vdd==false so in theory this is fine.

In the past that was perfectly fine since the vdd off work didn't do
anything when want_panel_vdd==false, so even if the work would have been
run during system resume before i915 has resumed, nothing would happen.

However since pps_lock() will now grab the power domain references before
it can check want_panel_vdd, we may end up toggling the power wells on/off
already before the driver has resumed. That is not really acceptable, so
cancel the vdd off work when suspending the encoder.

The problem appeared when pps_lock() was introduced in:
 commit 773538e86081d146e0020435d614f4b96996c1f9
 Author: Ville Syrjälä <ville.syrjala at linux.intel.com>
 Date:   Thu Sep 4 14:54:56 2014 +0300

    drm/i915: Reset power sequencer pipe tracking when disp2d is off

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 46731da..d2529ec 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4335,6 +4335,7 @@ static void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder)
 	 * vdd might still be enabled do to the delayed vdd off.
 	 * Make sure vdd is actually turned off here.
 	 */
+	cancel_delayed_work_sync(&intel_dp->panel_vdd_work);
 	pps_lock(intel_dp);
 	edp_panel_vdd_off_sync(intel_dp);
 	pps_unlock(intel_dp);
-- 
2.0.4