Re: [PATCH v2 09/11] drm/panthor: Process FW events in IRQ context

[Steven Price]

On 12/05/2026 12:37, Boris Brezillon wrote:
> Now that everything is set to allow processing FW events in IRQ context,
> go for it. This should reduce the dma_fence signaling latency.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>

Reviewed-by: Steven Price <steven.price@xxxxxxx>

> ---
>  drivers/gpu/drm/panthor/panthor_fw.c | 27 +++++++++++++++++++++++----
>  1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index f5e0ceca4130..8cfebf180de7 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -1087,9 +1087,29 @@ static void panthor_job_irq_handler(struct panthor_irq *pirq, u32 status)
>  	}
>  }
>  
> -static irqreturn_t panthor_job_irq_threaded_handler(int irq, void *data)
> +static irqreturn_t panthor_job_irq_raw_handler(int irq, void *data)
>  {
> -	return panthor_irq_default_threaded_handler(data, panthor_job_irq_handler);
> +	struct panthor_irq *pirq = data;
> +
> +	if (!gpu_read(pirq->iomem, INT_STAT))
> +		return IRQ_NONE;
> +
> +	scoped_guard(spinlock_irqsave, &pirq->mask_lock) {
> +		if (pirq->state != PANTHOR_IRQ_STATE_ACTIVE)
> +			return IRQ_NONE;
> +
> +		pirq->state = PANTHOR_IRQ_STATE_PROCESSING;
> +	}
> +
> +	/* We can use INT_STAT here, because we didn't mask the IRQs. */
> +	panthor_job_irq_handler(pirq, gpu_read(pirq->iomem, INT_STAT));
> +
> +	scoped_guard(spinlock_irqsave, &pirq->mask_lock) {
> +		if (pirq->state == PANTHOR_IRQ_STATE_PROCESSING)
> +			pirq->state = PANTHOR_IRQ_STATE_ACTIVE;
> +	}
> +
> +	return IRQ_HANDLED;
>  }
>  
>  static int panthor_fw_start(struct panthor_device *ptdev)
> @@ -1489,8 +1509,7 @@ int panthor_fw_init(struct panthor_device *ptdev)
>  
>  	ret = panthor_irq_request(ptdev, &fw->irq, irq, 0,
>  				  ptdev->iomem + JOB_INT_BASE, "job",
> -				  panthor_irq_default_raw_handler,
> -				  panthor_job_irq_threaded_handler);
> +				  panthor_job_irq_raw_handler, NULL);
>  	if (ret) {
>  		drm_err(&ptdev->base, "failed to request job irq");
>  		return ret;
>