| Message ID | 20250429-drm-msm-gpu-hot-devfreq-boot-v1-1-8aa9c5f266b4@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | drm/msm/gpu: Fix crash when throttling GPU immediately during boot | expand |
On 4/29/25 10:33 AM, Stephan Gerhold wrote: > There is a small chance that the GPU is already hot during boot. In that > case, the call to of_devfreq_cooling_register() will immediately try to > apply devfreq cooling, as seen in the following crash: > > Unable to handle kernel paging request at virtual address 0000000000014110 > pc : a6xx_gpu_busy+0x1c/0x58 [msm] > lr : msm_devfreq_get_dev_status+0xbc/0x140 [msm] > Call trace: > a6xx_gpu_busy+0x1c/0x58 [msm] (P) > devfreq_simple_ondemand_func+0x3c/0x150 > devfreq_update_target+0x44/0xd8 > qos_max_notifier_call+0x30/0x84 > blocking_notifier_call_chain+0x6c/0xa0 > pm_qos_update_target+0xd0/0x110 > freq_qos_apply+0x3c/0x74 > apply_constraint+0x88/0x148 > __dev_pm_qos_update_request+0x7c/0xcc > dev_pm_qos_update_request+0x38/0x5c > devfreq_cooling_set_cur_state+0x98/0xf0 > __thermal_cdev_update+0x64/0xb4 > thermal_cdev_update+0x4c/0x58 > step_wise_manage+0x1f0/0x318 > __thermal_zone_device_update+0x278/0x424 > __thermal_cooling_device_register+0x2bc/0x308 > thermal_of_cooling_device_register+0x10/0x1c > of_devfreq_cooling_register_power+0x240/0x2bc > of_devfreq_cooling_register+0x14/0x20 > msm_devfreq_init+0xc4/0x1a0 [msm] > msm_gpu_init+0x304/0x574 [msm] > adreno_gpu_init+0x1c4/0x2e0 [msm] > a6xx_gpu_init+0x5c8/0x9c8 [msm] > adreno_bind+0x2a8/0x33c [msm] > ... > > At this point we haven't initialized the GMU at all yet, so we cannot read > the GMU registers inside a6xx_gpu_busy(). A similar issue was fixed before > in commit 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in > 6xx gpu_busy"): msm_devfreq_init() does call devfreq_suspend_device(), but > unlike msm_devfreq_suspend(), it doesn't set the df->suspended flag > accordingly. This means the df->suspended flag does not match the actual > devfreq state after initialization and msm_devfreq_get_dev_status() will > end up accessing GMU registers, causing the crash. > > Fix this by setting df->suspended correctly during initialization. > > Cc: stable@vger.kernel.org > Fixes: 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in 6xx gpu_busy") > Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org> > --- Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com> Konrad
diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c index 6970b0f7f457c8535ecfeaa705db871594ae5fc4..2e1d5c3432728cde15d91f69da22bb915588fe86 100644 --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c @@ -156,6 +156,7 @@ void msm_devfreq_init(struct msm_gpu *gpu) priv->gpu_devfreq_config.downdifferential = 10; mutex_init(&df->lock); + df->suspended = true; ret = dev_pm_qos_add_request(&gpu->pdev->dev, &df->boost_freq, DEV_PM_QOS_MIN_FREQUENCY, 0);
There is a small chance that the GPU is already hot during boot. In that case, the call to of_devfreq_cooling_register() will immediately try to apply devfreq cooling, as seen in the following crash: Unable to handle kernel paging request at virtual address 0000000000014110 pc : a6xx_gpu_busy+0x1c/0x58 [msm] lr : msm_devfreq_get_dev_status+0xbc/0x140 [msm] Call trace: a6xx_gpu_busy+0x1c/0x58 [msm] (P) devfreq_simple_ondemand_func+0x3c/0x150 devfreq_update_target+0x44/0xd8 qos_max_notifier_call+0x30/0x84 blocking_notifier_call_chain+0x6c/0xa0 pm_qos_update_target+0xd0/0x110 freq_qos_apply+0x3c/0x74 apply_constraint+0x88/0x148 __dev_pm_qos_update_request+0x7c/0xcc dev_pm_qos_update_request+0x38/0x5c devfreq_cooling_set_cur_state+0x98/0xf0 __thermal_cdev_update+0x64/0xb4 thermal_cdev_update+0x4c/0x58 step_wise_manage+0x1f0/0x318 __thermal_zone_device_update+0x278/0x424 __thermal_cooling_device_register+0x2bc/0x308 thermal_of_cooling_device_register+0x10/0x1c of_devfreq_cooling_register_power+0x240/0x2bc of_devfreq_cooling_register+0x14/0x20 msm_devfreq_init+0xc4/0x1a0 [msm] msm_gpu_init+0x304/0x574 [msm] adreno_gpu_init+0x1c4/0x2e0 [msm] a6xx_gpu_init+0x5c8/0x9c8 [msm] adreno_bind+0x2a8/0x33c [msm] ... At this point we haven't initialized the GMU at all yet, so we cannot read the GMU registers inside a6xx_gpu_busy(). A similar issue was fixed before in commit 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in 6xx gpu_busy"): msm_devfreq_init() does call devfreq_suspend_device(), but unlike msm_devfreq_suspend(), it doesn't set the df->suspended flag accordingly. This means the df->suspended flag does not match the actual devfreq state after initialization and msm_devfreq_get_dev_status() will end up accessing GMU registers, causing the crash. Fix this by setting df->suspended correctly during initialization. Cc: stable@vger.kernel.org Fixes: 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in 6xx gpu_busy") Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org> --- drivers/gpu/drm/msm/msm_gpu_devfreq.c | 1 + 1 file changed, 1 insertion(+) --- base-commit: 33035b665157558254b3c21c3f049fd728e72368 change-id: 20250428-drm-msm-gpu-hot-devfreq-boot-36184dbc7075 Best regards,