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drm/panthor: Be robust against resume failures

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When the runtime PM resume callback returns an error, it puts the device
in a state where it can't be resumed anymore. Make sure we can recover
from such transient failures by calling pm_runtime_set_suspended()
explicitly after a pm_runtime_resume_and_get() failure.

v3:
- Add R-b/A-b

v2:
- Add a comment explaining potential races in
  panthor_device_resume_and_get()

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Adrian Larumbe <adrian.larumbe@collabora.com>
Acked-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241211075419.2333731-5-boris.brezillon@collabora.com
This commit is contained in:
Boris Brezillon 2024-12-11 08:54:18 +01:00
parent b0758224e5
commit 303e9e981d
4 changed files with 30 additions and 3 deletions
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1
drivers/gpu/drm/panthor/panthor_device.c
View File

@ -504,6 +504,7 @@ int panthor_device_resume(struct device *dev)
err_set_suspended:
atomic_set(&ptdev->pm.state, PANTHOR_DEVICE_PM_STATE_SUSPENDED);
atomic_set(&ptdev->pm.recovery_needed, 1);
return ret;
}

26
drivers/gpu/drm/panthor/panthor_device.h
View File

@ -9,6 +9,7 @@
#include <linux/atomic.h>
#include <linux/io-pgtable.h>
#include <linux/regulator/consumer.h>
#include <linux/pm_runtime.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
@ -180,6 +181,9 @@ struct panthor_device {
* is suspended.
*/
struct page *dummy_latest_flush;
/** @recovery_needed: True when a resume attempt failed. */
atomic_t recovery_needed;
} pm;
/** @profile_mask: User-set profiling flags for job accounting. */
@ -243,6 +247,28 @@ int panthor_device_mmap_io(struct panthor_device *ptdev,
int panthor_device_resume(struct device *dev);
int panthor_device_suspend(struct device *dev);
static inline int panthor_device_resume_and_get(struct panthor_device *ptdev)
{
int ret = pm_runtime_resume_and_get(ptdev->base.dev);
/* If the resume failed, we need to clear the runtime_error, which
* can done by forcing the RPM state to suspended. If multiple
* threads called panthor_device_resume_and_get(), we only want
* one of them to update the state, hence the cmpxchg. Note that a
* thread might enter panthor_device_resume_and_get() and call
* pm_runtime_resume_and_get() after another thread had attempted
* to resume and failed. This means we will end up with an error
* without even attempting a resume ourselves. The only risk here
* is to report an error when the second resume attempt might have
* succeeded. Given resume errors are not expected, this is probably
* something we can live with.
*/
if (ret && atomic_cmpxchg(&ptdev->pm.recovery_needed, 1, 0) == 1)
pm_runtime_set_suspended(ptdev->base.dev);
return ret;
}
enum drm_panthor_exception_type {
DRM_PANTHOR_EXCEPTION_OK = 0x00,
DRM_PANTHOR_EXCEPTION_TERMINATED = 0x04,

2
drivers/gpu/drm/panthor/panthor_drv.c
View File

@ -763,7 +763,7 @@ static int panthor_query_timestamp_info(struct panthor_device *ptdev,
{
int ret;
ret = pm_runtime_resume_and_get(ptdev->base.dev);
ret = panthor_device_resume_and_get(ptdev);
if (ret)
return ret;

4
drivers/gpu/drm/panthor/panthor_sched.c
View File

@ -2354,7 +2354,7 @@ static void tick_work(struct work_struct *work)
if (!drm_dev_enter(&ptdev->base, &cookie))
return;
ret = pm_runtime_resume_and_get(ptdev->base.dev);
ret = panthor_device_resume_and_get(ptdev);
if (drm_WARN_ON(&ptdev->base, ret))
goto out_dev_exit;
@ -3115,7 +3115,7 @@ queue_run_job(struct drm_sched_job *sched_job)
return dma_fence_get(job->done_fence);
}
ret = pm_runtime_resume_and_get(ptdev->base.dev);
ret = panthor_device_resume_and_get(ptdev);
if (drm_WARN_ON(&ptdev->base, ret))
return ERR_PTR(ret);