On Friday, 9 January 2026 17:05:05 Central European Standard Time Steven Price
wrote:
> On 08/01/2026 14:19, Nicolas Frattaroli wrote:
> > To deal with the threaded interrupt handler and a suspend action
> > overlapping, the boolean panthor_irq::suspended is not sufficient.
> >
> > Rework it into taking several different values depending on the current
> > state, and check it and set it within the IRQ helper functions.
> >
> > Signed-off-by: Nicolas Frattaroli <[email protected]>
> > ---
> > drivers/gpu/drm/panthor/panthor_device.h | 40
> > +++++++++++++++++++++++++-------
> > 1 file changed, 32 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_device.h
> > b/drivers/gpu/drm/panthor/panthor_device.h
> > index cf76a8abca76..a8c21a7eea05 100644
> > --- a/drivers/gpu/drm/panthor/panthor_device.h
> > +++ b/drivers/gpu/drm/panthor/panthor_device.h
> > @@ -61,6 +61,17 @@ enum panthor_device_pm_state {
> > PANTHOR_DEVICE_PM_STATE_SUSPENDING,
> > };
> >
> > +enum panthor_irq_state {
> > + /** @PANTHOR_IRQ_STATE_ACTIVE: IRQ is active and ready to process
> > events. */
> > + PANTHOR_IRQ_STATE_ACTIVE = 0,
> > + /** @PANTHOR_IRQ_STATE_PROCESSING: IRQ is currently processing events.
> > */
> > + PANTHOR_IRQ_STATE_PROCESSING,
> > + /** @PANTHOR_IRQ_STATE_SUSPENDED: IRQ is suspended. */
> > + PANTHOR_IRQ_STATE_SUSPENDED,
> > + /** @PANTHOR_IRQ_STATE_SUSPENDING: IRQ is being suspended. */
> > + PANTHOR_IRQ_STATE_SUSPENDING,
> > +};
> > +
> > /**
> > * struct panthor_irq - IRQ data
> > *
> > @@ -76,8 +87,8 @@ struct panthor_irq {
> > /** @mask: Values to write to xxx_INT_MASK if active. */
> > u32 mask;
> >
> > - /** @suspended: Set to true when the IRQ is suspended. */
> > - atomic_t suspended;
> > + /** @state: one of &enum panthor_irq_state reflecting the current
> > state. */
> > + atomic_t state;
> >
> > /** @mask_lock: protects modifications to _INT_MASK and @mask */
> > spinlock_t mask_lock;
> > @@ -415,7 +426,7 @@ static irqreturn_t panthor_ ## __name ##
> > _irq_raw_handler(int irq, void *data)
> >
> > \
> > guard(spinlock_irqsave)(&pirq->mask_lock);
> > \
> >
> > \
> > - if (atomic_read(&pirq->suspended))
> > \
> > + if (atomic_read(&pirq->state) == PANTHOR_IRQ_STATE_SUSPENDED)
> > \
>
> Do we want to also catch the STATE_SUSPENDING case here? AFAICT in
> SUSPENDING we should be confident that _INT_MASK==0 so this shouldn't a
> problem (_INT_STAT should read as 0 below). But we don't want interrupts
> during STATE_SUSPENDING so we might as well handle it.
Depends on what we want to happen here, I think. If the suspend handler
writing 0 to _INT_MASK does not also happen to clear _INT_STAT, then as
far as I can see, we may enter _irq_raw_handler, block for the lock as
suspend drops it, and then enter the function with STATE_SUSPENDING in
a context where we'd probably want to process the remaining interrupts
(i.e. suspend is at synchronise_irq() or about to be there, and we're
handling the last IRQ that got raised before mask was written to 0).
Let me know if my understanding here is correct, because I think in such
a case, it's reasonable to process that last IRQ instead of discarding it,
unless that's something frowned upon that I'm not aware of.
>
> Thanks,
> Steve
>
> > return IRQ_NONE;
> > \
> > if (!gpu_read(ptdev, __reg_prefix ## _INT_STAT))
> > \
> > return IRQ_NONE;
> > \
> > @@ -428,11 +439,14 @@ static irqreturn_t panthor_ ## __name ##
> > _irq_threaded_handler(int irq, void *da
> > {
> > \
> > struct panthor_irq *pirq = data;
> > \
> > struct panthor_device *ptdev = pirq->ptdev;
> > \
> > + enum panthor_irq_state state;
> > \
> > irqreturn_t ret = IRQ_NONE;
> > \
> > u32 mask;
> > \
> >
> > \
> > scoped_guard(spinlock_irqsave, &pirq->mask_lock) {
> > \
> > mask = pirq->mask;
> > \
> > + atomic_cmpxchg(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE,
> > \
> > + PANTHOR_IRQ_STATE_PROCESSING);
> > \
> > }
> > \
> >
> > \
> > while (true) {
> > \
> > @@ -446,11 +460,14 @@ static irqreturn_t panthor_ ## __name ##
> > _irq_threaded_handler(int irq, void *da
> > }
> > \
> >
> > \
> > scoped_guard(spinlock_irqsave, &pirq->mask_lock) {
> > \
> > - if (!atomic_read(&pirq->suspended)) {
> > \
> > + state = atomic_read(&pirq->state);
> > \
> > + if (state != PANTHOR_IRQ_STATE_SUSPENDED &&
> > \
> > + state != PANTHOR_IRQ_STATE_SUSPENDING) {
> > \
> > /* Only restore the bits that were used and are still
> > enabled */ \
> > gpu_write(ptdev, __reg_prefix ## _INT_MASK,
> > \
> > gpu_read(ptdev, __reg_prefix ## _INT_MASK) |
> > \
> > (mask & pirq->mask));
> > \
> > + atomic_set(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE);
> > \
> > }
> > \
> > }
> > \
> >
> > \
> > @@ -461,16 +478,17 @@ static inline void panthor_ ## __name ##
> > _irq_suspend(struct panthor_irq *pirq)
> > {
> > \
> > scoped_guard(spinlock_irqsave, &pirq->mask_lock) {
> > \
> > gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, 0);
> > \
> > + atomic_set(&pirq->state, PANTHOR_IRQ_STATE_SUSPENDING);
> > \
> > }
> > \
> > synchronize_irq(pirq->irq);
> > \
> > - atomic_set(&pirq->suspended, true);
> > \
> > + atomic_set(&pirq->state, PANTHOR_IRQ_STATE_SUSPENDED);
> > \
> > }
> > \
> >
> > \
> > static inline void panthor_ ## __name ## _irq_resume(struct panthor_irq
> > *pirq) \
> > {
> > \
> > guard(spinlock_irqsave)(&pirq->mask_lock);
> > \
> >
> > \
> > - atomic_set(&pirq->suspended, false);
> > \
> > + atomic_set(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE);
> > \
> > gpu_write(pirq->ptdev, __reg_prefix ## _INT_CLEAR, pirq->mask);
> > \
> > gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, pirq->mask);
> > \
> > }
> > \
> > @@ -494,19 +512,25 @@ static int panthor_request_ ## __name ## _irq(struct
> > panthor_device *ptdev, \
> >
> > \
> > static inline void panthor_ ## __name ## _irq_enable_events(struct
> > panthor_irq *pirq, u32 mask) \
> > {
> > \
> > + enum panthor_irq_state state;
> > \
> > +
> > \
> > guard(spinlock_irqsave)(&pirq->mask_lock);
> > \
> >
> > \
> > pirq->mask |= mask;
> > \
> > - if (!atomic_read(&pirq->suspended))
> > \
> > + state = atomic_read(&pirq->state);
> > \
> > + if (state != PANTHOR_IRQ_STATE_SUSPENDED && state !=
> > PANTHOR_IRQ_STATE_SUSPENDING) \
> > gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, pirq->mask);
> > \
> > }
> > \
> >
> > \
> > static inline void panthor_ ## __name ## _irq_disable_events(struct
> > panthor_irq *pirq, u32 mask)\
> > {
> > \
> > + enum panthor_irq_state state;
> > \
> > +
> > \
> > guard(spinlock_irqsave)(&pirq->mask_lock);
> > \
> >
> > \
> > pirq->mask &= ~mask;
> > \
> > - if (!atomic_read(&pirq->suspended))
> > \
> > + state = atomic_read(&pirq->state);
> > \
> > + if (state != PANTHOR_IRQ_STATE_SUSPENDED && state !=
> > PANTHOR_IRQ_STATE_SUSPENDING) \
> > gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, pirq->mask);
> > \
> > }
> >
> >
>
>
