drm: msm: a6xx: fix gpu failure after system resume

On targets where GMU is available, GMU takes over the ownership of GX GDSC
during its initialization. So, move the refcount-get on GX PD before we
initialize the GMU. This ensures that nobody can collapse the GX GDSC
once GMU owns the GX GDSC. This patch fixes some GMU OOB errors seen
during GPU wake up during a system resume.

Reported-by: Matthias Kaehlcke <[email protected]>
Signed-off-by: Akhil P Oommen <[email protected]>
Tested-by: Matthias Kaehlcke <[email protected]>
Reviewed-by: Jordan Crouse <[email protected]>
Signed-off-by: Rob Clark <[email protected]>

Author: Akhil P Oommen

drivers/gpu/drm/msm/adreno/a6xx_gmu.c

@@ -864,10 +864,19 @@ int a6xx_gmu_resume(struct a6xx_gpu *a6xx_gpu)
 	/* Turn on the resources */
 	pm_runtime_get_sync(gmu->dev);
 
+	/*
+	 * "enable" the GX power domain which won't actually do anything but it
+	 * will make sure that the refcounting is correct in case we need to
+	 * bring down the GX after a GMU failure
+	 */
+	if (!IS_ERR_OR_NULL(gmu->gxpd))
+		pm_runtime_get_sync(gmu->gxpd);
+
 	/* Use a known rate to bring up the GMU */
 	clk_set_rate(gmu->core_clk, 200000000);
 	ret = clk_bulk_prepare_enable(gmu->nr_clocks, gmu->clocks);
 	if (ret) {
+		pm_runtime_put(gmu->gxpd);
 		pm_runtime_put(gmu->dev);
 		return ret;
 	}
@@ -910,19 +919,12 @@ int a6xx_gmu_resume(struct a6xx_gpu *a6xx_gpu)
 	/* Set the GPU to the current freq */
 	a6xx_gmu_set_initial_freq(gpu, gmu);
 
-	/*
-	 * "enable" the GX power domain which won't actually do anything but it
-	 * will make sure that the refcounting is correct in case we need to
-	 * bring down the GX after a GMU failure
-	 */
-	if (!IS_ERR_OR_NULL(gmu->gxpd))
-		pm_runtime_get(gmu->gxpd);
-
 out:
 	/* On failure, shut down the GMU to leave it in a good state */
 	if (ret) {
 		disable_irq(gmu->gmu_irq);
 		a6xx_rpmh_stop(gmu);
+		pm_runtime_put(gmu->gxpd);
 		pm_runtime_put(gmu->dev);
 	}