Re: [PATCH v8 1/4] drm/panthor: Rework panthor_irq::suspended into panthor_irq::state

[Steven Price <steven.price@arm.com>]

On 12/01/2026 14:37, 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 <nicolas.frattaroli@collabora.com>

There are some unwanted changes in this patch. We want to keep it simple
so it does exactly what the changelog says. See below.

> ---
>  drivers/gpu/drm/panthor/panthor_device.h | 40 +++++++++++++++++++++++++-------
>  1 file changed, 31 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> index f35e52b9546a..424f6cd1a814 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: Current mask being applied to xxx_INT_MASK. */
>  	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;
>  };
>  
>  /**
> @@ -409,8 +420,10 @@ static irqreturn_t panthor_ ## __name ## _irq_raw_handler(int irq, void *data)
>  {												\
>  	struct panthor_irq *pirq = data;							\
>  	struct panthor_device *ptdev = pirq->ptdev;						\
> +	enum panthor_irq_state state;								\
>  												\
> -	if (atomic_read(&pirq->suspended))							\
> +	state = atomic_read(&pirq->state);							\
> +	if (state == PANTHOR_IRQ_STATE_SUSPENDED || state == PANTHOR_IRQ_STATE_SUSPENDING)	\
>  		return IRQ_NONE;								\
>  	if (!gpu_read(ptdev, __reg_prefix ## _INT_STAT))					\
>  		return IRQ_NONE;								\
> @@ -423,8 +436,11 @@ 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;								\
>  												\
> +	atomic_cmpxchg(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE, PANTHOR_IRQ_STATE_PROCESSING);	\
> +												\
>  	while (true) {										\
>  		u32 status = gpu_read(ptdev, __reg_prefix ## _INT_RAWSTAT) & pirq->mask;	\
>  												\
> @@ -435,8 +451,13 @@ static irqreturn_t panthor_ ## __name ## _irq_threaded_handler(int irq, void *da
>  		ret = IRQ_HANDLED;								\
>  	}											\
>  												\
> -	if (!atomic_read(&pirq->suspended))							\
> -		gpu_write(ptdev, __reg_prefix ## _INT_MASK, pirq->mask);			\
> +	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));	\

This change to read the _INT_MASK and mask pirq->mask with 'mask'
shouldn't be part of this patch.

> +		atomic_set(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE);				\
> +	}											\
>  												\
>  	return ret;										\
>  }												\
> @@ -445,16 +466,17 @@ static inline void panthor_ ## __name ## _irq_suspend(struct panthor_irq *pirq)
>  {												\
>  	pirq->mask = 0;										\
>  	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, u32 mask)	\
>  {												\
> -	atomic_set(&pirq->suspended, false);							\
>  	pirq->mask = mask;									\
> -	gpu_write(pirq->ptdev, __reg_prefix ## _INT_CLEAR, mask);				\
> -	gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, mask);				\
> +	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);				\

Here the change from using the local 'mask' to 'pirq->mask' is
unrelated. It belongs in the next patch where 'mask' is being removed.

But otherwise this looks good to me.

Thanks,
Steve

>  }												\
>  												\
>  static int panthor_request_ ## __name ## _irq(struct panthor_device *ptdev,			\
>