On Wed, Oct 22, 2025 at 12:32:41PM +0200, Ketil Johnsen wrote:
> There is a race between panthor_device_unplug() and
> panthor_device_suspend() which can lead to IRQ handlers running on a
> powered down GPU. This is how it can happen:
> - unplug routine calls drm_dev_unplug()
> - panthor_device_suspend() can now execute, and will skip a lot of
> important work because the device is currently marked as unplugged.
> - IRQs will remain active in this case and IRQ handlers can therefore
> try to access a powered down GPU.
>
> The fix is simply to take the PM ref in panthor_device_unplug() a
> little bit earlier, before drm_dev_unplug().
>
> Signed-off-by: Ketil Johnsen <[email protected]>
> Fixes: 5fe909cae118a ("drm/panthor: Add the device logical block")
Pushed to drm-misc-next.
Best regards,
Liviu
> ---
> drivers/gpu/drm/panthor/panthor_device.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c
> b/drivers/gpu/drm/panthor/panthor_device.c
> index 81df49880bd87..962a10e00848e 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -83,6 +83,8 @@ void panthor_device_unplug(struct panthor_device *ptdev)
> return;
> }
>
> + drm_WARN_ON(&ptdev->base, pm_runtime_get_sync(ptdev->base.dev) < 0);
> +
> /* Call drm_dev_unplug() so any access to HW blocks happening after
> * that point get rejected.
> */
> @@ -93,8 +95,6 @@ void panthor_device_unplug(struct panthor_device *ptdev)
> */
> mutex_unlock(&ptdev->unplug.lock);
>
> - drm_WARN_ON(&ptdev->base, pm_runtime_get_sync(ptdev->base.dev) < 0);
> -
> /* Now, try to cleanly shutdown the GPU before the device resources
> * get reclaimed.
> */
> --
> 2.47.2
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
