On Tue, Mar 26, 2024 at 12:12:04PM +0100, Boris Brezillon wrote:
> Make sure we set suspended=true last to avoid generating an irq storm
> in the unlikely case where an IRQ happens between the suspended=true
> assignment and the _INT_MASK update.
>
> We also move the mask=0 assignment before writing to the _INT_MASK
> register to prevent the thread handler from unmasking the interrupt
> behind our back. This means we might lose events if there were some
> pending when we get to suspend the IRQ, but that's fine.
> The synchronize_irq() we have in the _irq_suspend() path was not
> there to make sure all IRQs are processed, just to make sure we don't
> have registers accesses coming from the irq handlers after
> _irq_suspend() has been called. If there's a need to have all pending
> IRQs processed, it should happen before _irq_suspend() is called.
>
> v3:
> - Add Steve's R-b
>
> v2:
> - New patch
>
> Fixes: 5fe909cae118 ("drm/panthor: Add the device logical block")
> Reported-by: Steven Price <steven.price@xxxxxxx>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> Reviewed-by: Steven Price <steven.price@xxxxxxx>
Acked-by: Liviu Dudau <liviu.dudau@xxxxxxx>
Best regards,
Liviu
> ---
> drivers/gpu/drm/panthor/panthor_device.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> index 7ee4987a3796..3a930a368ae1 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.h
> +++ b/drivers/gpu/drm/panthor/panthor_device.h
> @@ -325,7 +325,7 @@ static inline void panthor_ ## __name ## _irq_suspend(struct panthor_irq *pirq)
> { \
> int cookie; \
> \
> - atomic_set(&pirq->suspended, true); \
> + pirq->mask = 0; \
> \
> if (drm_dev_enter(&pirq->ptdev->base, &cookie)) { \
> gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, 0); \
> @@ -333,7 +333,7 @@ static inline void panthor_ ## __name ## _irq_suspend(struct panthor_irq *pirq)
> drm_dev_exit(cookie); \
> } \
> \
> - pirq->mask = 0; \
> + atomic_set(&pirq->suspended, true); \
> } \
> \
> static inline void panthor_ ## __name ## _irq_resume(struct panthor_irq *pirq, u32 mask) \
> --
> 2.44.0
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
