drm/bridge: it6505: Setup links in it6505_irq_hpd

Move the DPCD read and link setup steps to HPD IRQ handler to remove
an unnecessary dependency between .detect callback and the HPD IRQ
handler before registering it6505 as a DRM bridge. This is safe because
there is always a .detect call after each HPD IRQ handler triggered by
the drm_helper_hpd_irq_event call.
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221013110411.1674359-3-treapking@chromium.org

drivers/gpu/drm/bridge/ite-it6505.c

@@ -725,28 +725,6 @@ static void it6505_calc_video_info(struct it6505 *it6505)
 			     DRM_MODE_ARG(&it6505->video_info));
 }
 
-static int it6505_drm_dp_link_probe(struct drm_dp_aux *aux,
-				    struct it6505_drm_dp_link *link)
-{
-	u8 values[3];
-	int err;
-
-	memset(link, 0, sizeof(*link));
-
-	err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
-	if (err < 0)
-		return err;
-
-	link->revision = values[0];
-	link->rate = drm_dp_bw_code_to_link_rate(values[1]);
-	link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;
-
-	if (values[2] & DP_ENHANCED_FRAME_CAP)
-		link->capabilities = DP_ENHANCED_FRAME_CAP;
-
-	return 0;
-}
-
 static int it6505_drm_dp_link_set_power(struct drm_dp_aux *aux,
 					struct it6505_drm_dp_link *link,
 					u8 mode)
@@ -1456,11 +1434,19 @@ static void it6505_parse_link_capabilities(struct it6505 *it6505)
 	int bcaps;
 
 	if (it6505->dpcd[0] == 0) {
-		it6505_aux_on(it6505);
-		it6505_get_dpcd(it6505, DP_DPCD_REV, it6505->dpcd,
-				ARRAY_SIZE(it6505->dpcd));
+		dev_err(dev, "DPCD is not initialized");
+		return;
 	}
 
+	memset(link, 0, sizeof(*link));
+
+	link->revision = it6505->dpcd[0];
+	link->rate = drm_dp_bw_code_to_link_rate(it6505->dpcd[1]);
+	link->num_lanes = it6505->dpcd[2] & DP_MAX_LANE_COUNT_MASK;
+
+	if (it6505->dpcd[2] & DP_ENHANCED_FRAME_CAP)
+		link->capabilities = DP_ENHANCED_FRAME_CAP;
+
 	DRM_DEV_DEBUG_DRIVER(dev, "DPCD Rev.: %d.%d",
 			     link->revision >> 4, link->revision & 0x0F);
 
@@ -2323,19 +2309,32 @@ static int it6505_process_hpd_irq(struct it6505 *it6505)
 static void it6505_irq_hpd(struct it6505 *it6505)
 {
 	struct device *dev = &it6505->client->dev;
+	int dp_sink_count;
 
 	it6505->hpd_state = it6505_get_sink_hpd_status(it6505);
 	DRM_DEV_DEBUG_DRIVER(dev, "hpd change interrupt, change to %s",
 			     it6505->hpd_state ? "high" : "low");
 
-	if (it6505->bridge.dev)
-		drm_helper_hpd_irq_event(it6505->bridge.dev);
-	DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count: %d",
-			     it6505->sink_count);
-
 	if (it6505->hpd_state) {
 		wait_for_completion_timeout(&it6505->wait_edid_complete,
 					    msecs_to_jiffies(6000));
+		it6505_aux_on(it6505);
+		if (it6505->dpcd[0] == 0) {
+			it6505_get_dpcd(it6505, DP_DPCD_REV, it6505->dpcd,
+					ARRAY_SIZE(it6505->dpcd));
+			it6505_variable_config(it6505);
+			it6505_parse_link_capabilities(it6505);
+		}
+		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
+
+		it6505_drm_dp_link_set_power(&it6505->aux, &it6505->link,
+					     DP_SET_POWER_D0);
+		dp_sink_count = it6505_dpcd_read(it6505, DP_SINK_COUNT);
+		it6505->sink_count = DP_GET_SINK_COUNT(dp_sink_count);
+
+		DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count: %d",
+				     it6505->sink_count);
+
 		it6505_lane_termination_on(it6505);
 		it6505_lane_power_on(it6505);
 
@@ -2363,6 +2362,9 @@ static void it6505_irq_hpd(struct it6505 *it6505)
 		it6505_lane_off(it6505);
 		it6505_link_reset_step_train(it6505);
 	}
+
+	if (it6505->bridge.dev)
+		drm_helper_hpd_irq_event(it6505->bridge.dev);
 }
 
 static void it6505_irq_hpd_irq(struct it6505 *it6505)
@@ -2625,26 +2627,14 @@ static enum drm_connector_status it6505_detect(struct it6505 *it6505)
 		goto unlock;
 
 	if (it6505->enable_drv_hold) {
-		status = it6505_get_sink_hpd_status(it6505) ?
-					connector_status_connected :
-					connector_status_disconnected;
+		status = it6505->hpd_state ? connector_status_connected :
+					     connector_status_disconnected;
 		goto unlock;
 	}
 
-	if (it6505_get_sink_hpd_status(it6505)) {
-		it6505_aux_on(it6505);
-		it6505_drm_dp_link_probe(&it6505->aux, &it6505->link);
+	if (it6505->hpd_state) {
 		it6505_drm_dp_link_set_power(&it6505->aux, &it6505->link,
 					     DP_SET_POWER_D0);
-		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
-
-		if (it6505->dpcd[0] == 0) {
-			it6505_get_dpcd(it6505, DP_DPCD_REV, it6505->dpcd,
-					ARRAY_SIZE(it6505->dpcd));
-			it6505_variable_config(it6505);
-			it6505_parse_link_capabilities(it6505);
-		}
-
 		dp_sink_count = it6505_dpcd_read(it6505, DP_SINK_COUNT);
 		it6505->sink_count = DP_GET_SINK_COUNT(dp_sink_count);
 		DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count:%d branch:%d",