drm/i915: make sure VDD is turned off during system suspend

Atm we may leave eDP VDD enabled during system suspend after the CRTCs
are disabled through an HPD->DPCD read event. So disable VDD during
suspend at a point when no HPDs can occur.

Note that runtime suspend doesn't have the same problem, since there the
RPM ref held by VDD provides already the needed serialization.

v2:
- add note to commit message about the runtime suspend path (Ville)
- use edp_panel_vdd_off_sync(), so we can keep the WARN in
  edp_panel_vdd_off() (Ville)
v3:
- rebased on -fixes (for_each_intel_encoder()->list_for_each_entry())
  (Imre)

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v2)
Cc: stable@vger.kernel.org (3.16+)
[Jani: fix sparse warning reported by Fengguang Wu]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index fe3431f..b8c8bbd 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -153,6 +153,12 @@ struct intel_encoder {
 	 * be set correctly before calling this function. */
 	void (*get_config)(struct intel_encoder *,
 			   struct intel_crtc_config *pipe_config);
+	/*
+	 * Called during system suspend after all pending requests for the
+	 * encoder are flushed (for example for DP AUX transactions) and
+	 * device interrupts are disabled.
+	 */
+	void (*suspend)(struct intel_encoder *);
 	int crtc_mask;
 	enum hpd_pin hpd_pin;
 };