drm/msm/dp: postpone irq_hpd event during connection pending state

irq_hpd event can only be executed at connected state. Therefore
irq_hpd event should be postponed if it happened at connection
pending state. This patch also make sure both link rate and lane
are valid before start link training.
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

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

@@ -693,6 +693,13 @@ static int dp_irq_hpd_handle(struct dp_display_private *dp, u32 data)
 		return 0;
 	}
 
+	if (state == ST_CONNECT_PENDING) {
+		/* wait until ST_CONNECTED */
+		dp_add_event(dp, EV_IRQ_HPD_INT, 0, 1); /* delay = 1 */
+		mutex_unlock(&dp->event_mutex);
+		return 0;
+	}
+
 	ret = dp_display_usbpd_attention_cb(&dp->pdev->dev);
 	if (ret == -ECONNRESET) { /* cable unplugged */
 		dp->core_initialized = false;

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

@@ -167,12 +167,18 @@ int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
 	panel = container_of(dp_panel, struct dp_panel_private, dp_panel);
 
 	rc = dp_panel_read_dpcd(dp_panel);
+	if (rc) {
+		DRM_ERROR("read dpcd failed %d\n", rc);
+		return rc;
+	}
+
 	bw_code = drm_dp_link_rate_to_bw_code(dp_panel->link_info.rate);
-	if (rc || !is_link_rate_valid(bw_code) ||
+	if (!is_link_rate_valid(bw_code) ||
 			!is_lane_count_valid(dp_panel->link_info.num_lanes) ||
 			(bw_code > dp_panel->max_bw_code)) {
-		DRM_ERROR("read dpcd failed %d\n", rc);
-		return rc;
+		DRM_ERROR("Illegal link rate=%d lane=%d\n", dp_panel->link_info.rate,
+				dp_panel->link_info.num_lanes);
+		return -EINVAL;
 	}
 
 	if (dp_panel->dfp_present) {