[PATCH] drm/i915/psr: Fix PSR sink enable sequence

[Ville Syrjala <ville.syrjala@linux.intel.com>]

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

According to the eDP spec, the source must first configure all
PSR related DPCD registers apart from the actual enable bit,
and only then set the enable bit. Split the current single DPCD
write to two to match the spec.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_psr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 1a4ef231a53c..2b7c0c73f335 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -745,7 +745,7 @@ static void _psr_enable_sink(struct intel_dp *intel_dp,
 			     const struct intel_crtc_state *crtc_state)
 {
 	struct intel_display *display = to_intel_display(intel_dp);
-	u8 val = DP_PSR_ENABLE;
+	u8 val = 0;
 
 	if (crtc_state->has_sel_update) {
 		val |= DP_PSR_ENABLE_PSR2 | DP_PSR_IRQ_HPD_WITH_CRC_ERRORS;
@@ -765,7 +765,9 @@ static void _psr_enable_sink(struct intel_dp *intel_dp,
 
 	if (intel_dp->psr.entry_setup_frames > 0)
 		val |= DP_PSR_FRAME_CAPTURE;
+	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, val);
 
+	val |= DP_PSR_ENABLE;
 	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, val);
 }
 
-- 
2.44.2