drm/msm/dp: protect audio functionality during link maintenance

Link maintenance request from sink can be issued asynchronously
along with audio on/off functionalities. Link maintenance may
switch off and on the clocks needed for audio functionalities.
Protect the audio functionalities using lock to make sure the
required clocks are on.

CRs-Fixed: 2123895
Change-Id: I33e977b1e18feb205427a76171fd9b41fe463262
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>
[cohens@codeaurora.org: Corrected a spelling mistake in
        comment block reported by checkpatch]
Signed-off-by: Steve Cohen <cohens@codeaurora.org>

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

@@ -465,12 +465,16 @@ static int dp_audio_info_setup(struct platform_device *pdev,
 		goto end;
 	}
 
+	mutex_lock(&audio->dp_audio.ops_lock);
+
 	audio->channels = params->num_of_channels;
 
 	dp_audio_setup_sdp(audio);
 	dp_audio_setup_acr(audio);
 	dp_audio_safe_to_exit_level(audio);
 	dp_audio_enable(audio, true);
+
+	mutex_unlock(&audio->dp_audio.ops_lock);
 end:
 	return rc;
 }
@@ -545,7 +549,9 @@ static void dp_audio_teardown_done(struct platform_device *pdev)
 	if (IS_ERR(audio))
 		return;
 
+	mutex_lock(&audio->dp_audio.ops_lock);
 	dp_audio_enable(audio, false);
+	mutex_unlock(&audio->dp_audio.ops_lock);
 
 	complete_all(&audio->hpd_comp);
 
@@ -756,6 +762,8 @@ struct dp_audio *dp_audio_get(struct platform_device *pdev,
 
 	dp_audio = &audio->dp_audio;
 
+	mutex_init(&dp_audio->ops_lock);
+
 	dp_audio->on  = dp_audio_on;
 	dp_audio->off = dp_audio_off;
 
@@ -780,6 +788,7 @@ void dp_audio_put(struct dp_audio *dp_audio)
 		return;
 
 	audio = container_of(dp_audio, struct dp_audio_private, dp_audio);
+	mutex_destroy(&dp_audio->ops_lock);
 
 	devm_kfree(&audio->pdev->dev, audio);
 }

drivers/gpu/drm/msm/dp/dp_audio.h

@@ -29,6 +29,8 @@ struct dp_audio {
 	u32 lane_count;
 	u32 bw_code;
 
+	struct mutex ops_lock;
+
 	/**
 	 * on()
 	 *

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

@@ -1262,31 +1262,43 @@ static void dp_ctrl_send_phy_test_pattern(struct dp_ctrl_private *ctrl)
 			dp_link_get_phy_test_pattern(pattern_requested));
 }
 
-static void dp_ctrl_handle_sink_request(struct dp_ctrl *dp_ctrl)
+static bool dp_ctrl_handle_sink_request(struct dp_ctrl *dp_ctrl)
 {
 	struct dp_ctrl_private *ctrl;
 	u32 sink_request = 0x0;
+	bool req_handled = false;
 
 	if (!dp_ctrl) {
 		pr_err("invalid input\n");
-		return;
+		goto end;
 	}
 
 	ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl);
 	sink_request = ctrl->link->sink_request;
 
 	if (sink_request & DP_TEST_LINK_PHY_TEST_PATTERN) {
-		pr_info("PHY_TEST_PATTERN request\n");
+		pr_info("PHY_TEST_PATTERN\n");
 		dp_ctrl_process_phy_test_request(ctrl);
+
+		req_handled = true;
 	}
 
-	if (sink_request & DP_LINK_STATUS_UPDATED)
+	if (sink_request & DP_LINK_STATUS_UPDATED) {
+		pr_info("DP_LINK_STATUS_UPDATED\n");
 		dp_ctrl_link_maintenance(ctrl);
 
+		req_handled = true;
+	}
+
 	if (sink_request & DP_TEST_LINK_TRAINING) {
+		pr_info("DP_TEST_LINK_TRAINING\n");
 		ctrl->link->send_test_response(ctrl->link);
 		dp_ctrl_link_maintenance(ctrl);
+
+		req_handled = true;
 	}
+end:
+	return req_handled;
 }
 
 static void dp_ctrl_reset(struct dp_ctrl *dp_ctrl)

drivers/gpu/drm/msm/dp/dp_ctrl.h

@@ -31,7 +31,7 @@ struct dp_ctrl {
 	void (*push_idle)(struct dp_ctrl *dp_ctrl);
 	void (*abort)(struct dp_ctrl *dp_ctrl);
 	void (*isr)(struct dp_ctrl *dp_ctrl);
-	void (*handle_sink_request)(struct dp_ctrl *dp_ctrl);
+	bool (*handle_sink_request)(struct dp_ctrl *dp_ctrl);
 };
 
 struct dp_ctrl_in {

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

@@ -671,6 +671,8 @@ static void dp_display_handle_video_request(struct dp_display_private *dp)
 
 static int dp_display_handle_hpd_irq(struct dp_display_private *dp)
 {
+	bool req_handled;
+
 	if (dp->link->sink_request & DS_PORT_STATUS_CHANGED) {
 		dp_display_send_hpd_notification(dp, false);
 
@@ -682,7 +684,18 @@ static int dp_display_handle_hpd_irq(struct dp_display_private *dp)
 		return dp_display_process_hpd_high(dp);
 	}
 
-	dp->ctrl->handle_sink_request(dp->ctrl);
+	mutex_lock(&dp->audio->ops_lock);
+	req_handled = dp->ctrl->handle_sink_request(dp->ctrl);
+	mutex_unlock(&dp->audio->ops_lock);
+
+	/*
+	 * reconfigure audio if test was executed
+	 * which could have changed the controller's state
+	 */
+	if (req_handled && dp->audio_supported) {
+		dp->audio->off(dp->audio);
+		dp->audio->on(dp->audio);
+	}
 
 	dp_display_handle_video_request(dp);