linux-kernel - Re: [PATCH] drm/qxl: return IRQ

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Date:	Tue, 20 May 2014 16:22:04 +0800
From:	Amos Kong <akong@...hat.com>
To:	Jason Wang <jasowang@...hat.com>
Cc:	airlied@...ux.ie, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, Gerd Hoffmann <kraxel@...hat.com>,
	stable@...r.kernel.org
Subject: Re: [PATCH] drm/qxl: return IRQ_NONE if it was not our irq

On Mon, May 12, 2014 at 04:35:39PM +0800, Jason Wang wrote:
> Return IRQ_NONE if it was not our irq. This is necessary for the case
> when qxl is sharing irq line with a device A in a crash kernel. If qxl
> is initialized before A and A's irq was raised during this gap,
> returning IRQ_HANDLED in this case will cause this irq to be raised
> again after EOI since kernel think it was handled but in fact it was
> not.
> 
> Cc: Gerd Hoffmann <kraxel@...hat.com>
> Cc: stable@...r.kernel.org
> Signed-off-by: Jason Wang <jasowang@...hat.com>
> ---
>  drivers/gpu/drm/qxl/qxl_irq.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_irq.c b/drivers/gpu/drm/qxl/qxl_irq.c
> index 28f84b4..3485bdc 100644
> --- a/drivers/gpu/drm/qxl/qxl_irq.c
> +++ b/drivers/gpu/drm/qxl/qxl_irq.c
> @@ -33,6 +33,9 @@ irqreturn_t qxl_irq_handler(int irq, void *arg)
>  
>  	pending = xchg(&qdev->ram_header->int_pending, 0);
>  
> +	if (!pending)
> +		return IRQ_NONE;
> +

Looks correct.

Revewed-by: Amos Kong <akong@...hat.com>

>  	atomic_inc(&qdev->irq_received);
>  
>  	if (pending & QXL_INTERRUPT_DISPLAY) {
> -- 
> 1.9.1
> 
> --
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-- 
			Amos.
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