linux-kernel - [PATCH v2] drm/msm: Grab the GPU runtime in a6xx routines, not the GMU one

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Message-Id: <20220609094716.v2.1.Ie846c5352bc307ee4248d7cab998ab3016b85d06@changeid>
Date:   Thu,  9 Jun 2022 09:47:35 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Rob Clark <robdclark@...il.com>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>,
        Jordan Crouse <jordan@...micpenguin.net>
Cc:     Douglas Anderson <dianders@...omium.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Chia-I Wu <olvaffe@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Eric Anholt <eric@...olt.net>,
        Jonathan Marek <jonathan@...ek.ca>,
        Sean Paul <sean@...rly.run>, Wang Qing <wangqing@...o.com>,
        Yangtao Li <tiny.windzz@...il.com>,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] drm/msm: Grab the GPU runtime in a6xx routines, not the GMU one

>From testing on sc7180-trogdor devices, reading the GMU registers
needs the GMU clocks to be enabled. Those clocks get turned on in
a6xx_gmu_resume(). Confusingly enough, that function is called as a
result of the runtime_pm of the GPU "struct device", not the GMU
"struct device".

Let's grab a reference to the correct device. Incidentally, this makes
us match the a5xx routine more closely.

This is easily shown to fix crashes that happen if we change the GPU's
pm_runtime usage to not use autosuspend. It's also believed to fix
some long tail GPU crashes even with autosuspend.

NOTE: the crashes I've seen were fixed by _only_ fixing
a6xx_gpu_busy(). However, I believe that the same arguments should be
made to a6xx_gmu_set_freq() so I've fixed that case too. To make that
fix clean, we've moved the pm runtime grabbing into the GPU file.

As a bonus fix with this change, we change the pm_runtime get
functions to check for <= 0 instead of ==. This handles the case where
pm_runtime is disabled.

Fixes: eadf79286a4b ("drm/msm: Check for powered down HW in the devfreq callbacks")
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

Changes in v2:
- Move the set_freq runtime pm grab to the GPU file.
- Use <= for the pm_runtime test, not ==.

 drivers/gpu/drm/msm/adreno/a6xx_gmu.c |  9 ---------
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 13 +++++++++++--
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index 9f76f5b15759..2410815e77b4 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -125,17 +125,9 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
 
 	trace_msm_gmu_freq_change(gmu->freq, perf_index);
 
-	/*
-	 * This can get called from devfreq while the hardware is idle. Don't
-	 * bring up the power if it isn't already active
-	 */
-	if (pm_runtime_get_if_in_use(gmu->dev) == 0)
-		return;
-
 	if (!gmu->legacy) {
 		a6xx_hfi_set_freq(gmu, perf_index);
 		dev_pm_opp_set_opp(&gpu->pdev->dev, opp);
-		pm_runtime_put(gmu->dev);
 		return;
 	}
 
@@ -159,7 +151,6 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
 		dev_err(gmu->dev, "GMU set GPU frequency error: %d\n", ret);
 
 	dev_pm_opp_set_opp(&gpu->pdev->dev, opp);
-	pm_runtime_put(gmu->dev);
 }
 
 unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu)
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 42ed9a3c4905..54efd9b76ea6 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1659,7 +1659,7 @@ static u64 a6xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
 	*out_sample_rate = 19200000;
 
 	/* Only read the gpu busy if the hardware is already active */
-	if (pm_runtime_get_if_in_use(a6xx_gpu->gmu.dev) == 0)
+	if (pm_runtime_get_if_in_use(&gpu->pdev->dev) <= 0)
 		return 0;
 
 	busy_cycles = gmu_read64(&a6xx_gpu->gmu,
@@ -1667,7 +1667,7 @@ static u64 a6xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
 			REG_A6XX_GMU_CX_GMU_POWER_COUNTER_XOCLK_0_H);
 
 
-	pm_runtime_put(a6xx_gpu->gmu.dev);
+	pm_runtime_put(&gpu->pdev->dev);
 
 	return busy_cycles;
 }
@@ -1677,9 +1677,18 @@ static void a6xx_gpu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 
+	/*
+	 * This can get called from devfreq while the hardware is idle. Don't
+	 * bring up the power if it isn't already active
+	 */
+	if (pm_runtime_get_if_in_use(&gpu->pdev->dev) <= 0)
+		return;
+
 	mutex_lock(&a6xx_gpu->gmu.lock);
 	a6xx_gmu_set_freq(gpu, opp);
 	mutex_unlock(&a6xx_gpu->gmu.lock);
+
+	pm_runtime_put(&gpu->pdev->dev);
 }
 
 static struct msm_gem_address_space *
-- 
2.36.1.255.ge46751e96f-goog