[[SRU][Q]PATCH 1/2] drm/i915/psr: Check drm_dp_dpcd_read return value on PSR dpcd init

[AceLan Kao]

From: Jouni Högander <jouni.hogander at intel.com>

BugLink: https://bugs.launchpad.net/bugs/2136979

Currently we are ignoriong drm_dp_dpcd_read return values when reading PSR
and Panel Replay capability DPCD register. Rework intel_psr_dpcd a bit to
take care of checking the return value.

v2: use drm_dp_dpcd_read_data

Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
Reviewed-by: Jani Nikula <jani.nikula at intel.com>
Link: https://lore.kernel.org/r/20250821045918.17757-1-jouni.hogander@intel.com
(cherry picked from commit 9cc10041e9fe7f32c4817e3cdd806ff1986d266c)
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>
---
 drivers/gpu/drm/i915/display/intel_psr.c | 32 ++++++++++++++++--------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 85e9aad7ec507..ba80f8b36cd78 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -600,6 +600,16 @@ static void intel_dp_get_su_granularity(struct intel_dp *intel_dp)
 static void _panel_replay_init_dpcd(struct intel_dp *intel_dp)
 {
 	struct intel_display *display = to_intel_display(intel_dp);
+	int ret;
+
+	ret = drm_dp_dpcd_read_data(&intel_dp->aux, DP_PANEL_REPLAY_CAP_SUPPORT,
+				    &intel_dp->pr_dpcd, sizeof(intel_dp->pr_dpcd));
+	if (ret < 0)
+		return;
+
+	if (!(intel_dp->pr_dpcd[INTEL_PR_DPCD_INDEX(DP_PANEL_REPLAY_CAP_SUPPORT)] &
+	      DP_PANEL_REPLAY_SUPPORT))
+		return;
 
 	if (intel_dp_is_edp(intel_dp)) {
 		if (!intel_alpm_aux_less_wake_supported(intel_dp)) {
@@ -631,6 +641,15 @@ static void _panel_replay_init_dpcd(struct intel_dp *intel_dp)
 static void _psr_init_dpcd(struct intel_dp *intel_dp)
 {
 	struct intel_display *display = to_intel_display(intel_dp);
+	int ret;
+
+	ret = drm_dp_dpcd_read_data(&intel_dp->aux, DP_PSR_SUPPORT, intel_dp->psr_dpcd,
+				    sizeof(intel_dp->psr_dpcd));
+	if (ret < 0)
+		return;
+
+	if (!intel_dp->psr_dpcd[0])
+		return;
 
 	drm_dbg_kms(display->drm, "eDP panel supports PSR version %x\n",
 		    intel_dp->psr_dpcd[0]);
@@ -676,18 +695,9 @@ static void _psr_init_dpcd(struct intel_dp *intel_dp)
 
 void intel_psr_init_dpcd(struct intel_dp *intel_dp)
 {
-	drm_dp_dpcd_read(&intel_dp->aux, DP_PSR_SUPPORT, intel_dp->psr_dpcd,
-			 sizeof(intel_dp->psr_dpcd));
-
-	drm_dp_dpcd_read(&intel_dp->aux, DP_PANEL_REPLAY_CAP_SUPPORT,
-			 &intel_dp->pr_dpcd, sizeof(intel_dp->pr_dpcd));
-
-	if (intel_dp->pr_dpcd[INTEL_PR_DPCD_INDEX(DP_PANEL_REPLAY_CAP_SUPPORT)] &
-	    DP_PANEL_REPLAY_SUPPORT)
-		_panel_replay_init_dpcd(intel_dp);
+	_psr_init_dpcd(intel_dp);
 
-	if (intel_dp->psr_dpcd[0])
-		_psr_init_dpcd(intel_dp);
+	_panel_replay_init_dpcd(intel_dp);
 
 	if (intel_dp->psr.sink_psr2_support ||
 	    intel_dp->psr.sink_panel_replay_su_support)
-- 
2.43.0