drm/i915/psr: Fix PSR sink enable sequence

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>
Link: https://patchwork.freedesktop.org/patch/msgid/20240911151836.16800-1-ville.syrjala@linux.intel.com
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 5ed446f..5b355d0 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -764,7 +764,7 @@ 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;
@@ -784,7 +784,9 @@ 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);
 }