drm/msm/gpu: fix clk lockup PM suspend/resume handler

testing freq. transitions on MSM8916 Samsung J5 "a3xx":
locks up when gpu was on 310MHz:

resume handler was setting opp rate that will do clk_set_rate before
the clk was enabled.

devfreq can do this job if opp-suspend was defined in dt.

changed resume so clk gets enabled first and let devfreq setting it

changed suspend aswell

Signed-off-by: Christoph Rudorff <chris@rudorff.com>

drivers/gpu/drm/msm/msm_gpu.c

@@ -57,31 +57,44 @@ static int disable_pwrrail(struct msm_gpu *gpu)
 
 static int enable_clk(struct msm_gpu *gpu)
 {
-	if (gpu->core_clk && gpu->fast_rate)
+	int ret;
+	ret = clk_bulk_prepare_enable(gpu->nr_clocks, gpu->grp_clks);
+	if (ret)
+		return ret;
+	/*
+	  devfreq_resume_device() will do set_rate
+	  if an "opp-suspend" exists
+	*/
+	if (gpu->core_clk && gpu->fast_rate &&
+			dev_pm_opp_get_suspend_opp_freq(&gpu->pdev->dev) == 0)
 		dev_pm_opp_set_rate(&gpu->pdev->dev, gpu->fast_rate);
 
 	/* Set the RBBM timer rate to 19.2Mhz */
 	if (gpu->rbbmtimer_clk)
 		clk_set_rate(gpu->rbbmtimer_clk, 19200000);
 
-	return clk_bulk_prepare_enable(gpu->nr_clocks, gpu->grp_clks);
+	return 0;
 }
 
 static int disable_clk(struct msm_gpu *gpu)
 {
-	clk_bulk_disable_unprepare(gpu->nr_clocks, gpu->grp_clks);
-
 	/*
 	 * Set the clock to a deliberately low rate. On older targets the clock
 	 * speed had to be non zero to avoid problems. On newer targets this
 	 * will be rounded down to zero anyway so it all works out.
+
+	 * skip this if an "opp-suspend" exists:
+	 * devfreq_suspend_device() has done this
 	 */
-	if (gpu->core_clk)
-		dev_pm_opp_set_rate(&gpu->pdev->dev, 27000000);
+	if (gpu->core_clk &&
+			dev_pm_opp_get_suspend_opp_freq(&gpu->pdev->dev) == 0)
+		dev_pm_opp_set_rate(&gpu->pdev->dev, 1);
 
 	if (gpu->rbbmtimer_clk)
 		clk_set_rate(gpu->rbbmtimer_clk, 0);
 
+	clk_bulk_disable_unprepare(gpu->nr_clocks, gpu->grp_clks);
+
 	return 0;
 }
 

drivers/gpu/drm/msm/msm_gpu_devfreq.c

@@ -247,10 +247,10 @@ void msm_devfreq_suspend(struct msm_gpu *gpu)
 	df->suspended = true;
 	mutex_unlock(&df->lock);
 
-	devfreq_suspend_device(df->devfreq);
-
 	cancel_idle_work(df);
 	cancel_boost_work(df);
+
+	devfreq_suspend_device(df->devfreq);
 }
 
 static void msm_devfreq_boost_work(struct kthread_work *work)