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

[Boris Brezillon]

On Tue, 12 May 2026 13:37:41 +0200
Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> wrote:

> The current panthor_gpu_irq_handler() logic is already IRQ-safe
> (no sleep or sleeping locks, spinlocks taken with irqsave in other
> contexts, etc), so let's toggle the switch and make it an hard IRQ
> handler.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/panthor/panthor_gpu.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
> index b9c51f8a051d..04c8f23baf3f 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> @@ -86,10 +86,15 @@ static void panthor_gpu_l2_config_set(struct panthor_device *ptdev)
>  	gpu_write(gpu->iomem, GPU_L2_CONFIG, l2_config);
>  }
>  
> -static void panthor_gpu_irq_handler(struct panthor_irq *pirq, u32 status)
> +static irqreturn_t panthor_gpu_irq_raw_handler(int irq, void *data)
>  {
> +	struct panthor_irq *pirq = data;
>  	struct panthor_device *ptdev = pirq->ptdev;
>  	struct panthor_gpu *gpu = ptdev->gpu;
> +	u32 status = gpu_read(gpu->irq.iomem, INT_STAT);
> +
> +	if (!status)
> +		return IRQ_NONE;
>  

Forgot to add the pirq state transition here:

       scoped_guard(spinlock_irqsave, &pirq->mask_lock) {
               if (pirq->state != PANTHOR_IRQ_STATE_ACTIVE)
                       return IRQ_NONE;

               pirq->state = PANTHOR_IRQ_STATE_PROCESSING;
       }

>  	gpu_write(gpu->irq.iomem, INT_CLEAR, status);
>  
> @@ -115,11 +120,8 @@ static void panthor_gpu_irq_handler(struct panthor_irq *pirq, u32 status)
>  		ptdev->gpu->pending_reqs &= ~status;
>  		wake_up_all(&ptdev->gpu->reqs_acked);
>  	}
> -}
>  
> -static irqreturn_t panthor_gpu_irq_threaded_handler(int irq, void *data)
> -{
> -	return panthor_irq_default_threaded_handler(data, panthor_gpu_irq_handler);

and restore it here:

       scoped_guard(spinlock_irqsave, &pirq->mask_lock) {
               if (pirq->state == PANTHOR_IRQ_STATE_PROCESSING)
                       pirq->state = PANTHOR_IRQ_STATE_ACTIVE;
       }

> +	return IRQ_HANDLED;
>  }
>  
>  /**
> @@ -176,8 +178,7 @@ int panthor_gpu_init(struct panthor_device *ptdev)
>  	ret = panthor_irq_request(ptdev, &ptdev->gpu->irq, irq,
>  				  GPU_INTERRUPTS_MASK,
>  				  ptdev->iomem + GPU_INT_BASE, "gpu",
> -				  panthor_irq_default_raw_handler,
> -				  panthor_gpu_irq_threaded_handler);
> +				  panthor_gpu_irq_raw_handler, NULL);
>  	if (ret)
>  		return ret;
>  
>