drm/msm/dp: Fix support of LTTPR initialization

Initialize LTTPR before msm_dp_panel_read_sink_caps, as DPTX shall
(re)read DPRX caps after LTTPR detection, as required by DP 2.1a,
Section 3.6.7.6.1.

Fixes: 72d0af4 ("drm/msm/dp: Add support for LTTPR handling")
Reviewed-by: Abhinav Kumar <[email protected]>
Reviewed-by: Dmitry Baryshkov <[email protected]>
Signed-off-by: Aleksandrs Vinarskis <[email protected]>
Tested-by: Jessica Zhang <[email protected]> # SA8775P
Tested-by: Johan Hovold <[email protected]>
Tested-by: Rob Clark <[email protected]>
Patchwork: https://patchwork.freedesktop.org/patch/652301/
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Dmitry Baryshkov <[email protected]>

Author: alexVinarskis

drivers/gpu/drm/msm/dp/dp_display.c

@@ -360,12 +360,12 @@ static int msm_dp_display_send_hpd_notification(struct msm_dp_display_private *d
 	return 0;
 }
 
-static void msm_dp_display_lttpr_init(struct msm_dp_display_private *dp)
+static void msm_dp_display_lttpr_init(struct msm_dp_display_private *dp, u8 *dpcd)
 {
 	u8 lttpr_caps[DP_LTTPR_COMMON_CAP_SIZE];
 	int rc;
 
-	if (drm_dp_read_lttpr_common_caps(dp->aux, dp->panel->dpcd, lttpr_caps))
+	if (drm_dp_read_lttpr_common_caps(dp->aux, dpcd, lttpr_caps))
 		return;
 
 	rc = drm_dp_lttpr_init(dp->aux, drm_dp_lttpr_count(lttpr_caps));
@@ -378,12 +378,17 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
 	struct drm_connector *connector = dp->msm_dp_display.connector;
 	const struct drm_display_info *info = &connector->display_info;
 	int rc = 0;
+	u8 dpcd[DP_RECEIVER_CAP_SIZE];
 
-	rc = msm_dp_panel_read_sink_caps(dp->panel, connector);
+	rc = drm_dp_read_dpcd_caps(dp->aux, dpcd);
 	if (rc)
 		goto end;
 
-	msm_dp_display_lttpr_init(dp);
+	msm_dp_display_lttpr_init(dp, dpcd);
+
+	rc = msm_dp_panel_read_sink_caps(dp->panel, connector);
+	if (rc)
+		goto end;
 
 	msm_dp_link_process_request(dp->link);