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drm/panthor: Fix a race between the reset and suspend path

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If a reset is scheduled when the suspend happens, we drop the
reset-pending info on the floor assuming the resume will fix things,
but the resume logic might try a fast reset. If we're lucky, the
fast reset fails and we fallback to a slow reset, but if the FW was
corrupted in a way that makes it partially functional (it boots but
doesn't quite do what it's expected to do), we won't notice immediately
that things are not working correctly, leading to a new reset further
down the road.

Fixes: 5fe909cae1 ("drm/panthor: Add the device logical block")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241217092457.1582053-1-boris.brezillon@collabora.com
This commit is contained in:
Boris Brezillon 2024-12-17 10:24:57 +01:00 • committed by ChenJiali
commit 4250372745
1 changed files with 12 additions and 10 deletions
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22
drivers/gpu/drm/panthor/panthor_device.c
View file

@ -128,14 +128,11 @@ static void panthor_device_reset_work(struct work_struct *work)
struct panthor_device *ptdev = container_of(work, struct panthor_device, reset.work);
int ret = 0, cookie;
if (atomic_read(&ptdev->pm.state) != PANTHOR_DEVICE_PM_STATE_ACTIVE) {
/*
* No need for a reset as the device has been (or will be)
* powered down
*/
atomic_set(&ptdev->reset.pending, 0);
/* If the device is entering suspend, we don't reset. A slow reset will
* be forced at resume time instead.
*/
if (atomic_read(&ptdev->pm.state) != PANTHOR_DEVICE_PM_STATE_ACTIVE)
return;
}
if (!drm_dev_enter(&ptdev->base, &cookie))
return;
@ -476,6 +473,14 @@ int panthor_device_resume(struct device *dev)
if (panthor_device_is_initialized(ptdev) &&
drm_dev_enter(&ptdev->base, &cookie)) {
/* If there was a reset pending at the time we suspended the
* device, we force a slow reset.
*/
if (atomic_read(&ptdev->reset.pending)) {
ptdev->reset.fast = false;
atomic_set(&ptdev->reset.pending, 0);
}
ret = panthor_device_resume_hw_components(ptdev);
if (ret && ptdev->reset.fast) {
drm_err(&ptdev->base, "Fast reset failed, trying a slow reset");
@ -492,9 +497,6 @@ int panthor_device_resume(struct device *dev)
goto err_suspend_devfreq;
}
if (atomic_read(&ptdev->reset.pending))
queue_work(ptdev->reset.wq, &ptdev->reset.work);
/* Clear all IOMEM mappings pointing to this device after we've
* resumed. This way the fake mappings pointing to the dummy pages
* are removed and the real iomem mapping will be restored on next