linux-kernel - Re: [PATCH v3] media: aspeed-video: ignore interrupts that aren't enabled

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Message-ID: <46edf81d60a38747f7d2511f840253a1c6867652.camel@linux.ibm.com>
Date:   Wed, 01 Sep 2021 10:07:24 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     Zev Weiss <zev@...ilderbeest.net>
Cc:     Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>,
        Ryan Chen <ryan_chen@...eedtech.com>,
        linux-aspeed@...ts.ozlabs.org, Andrew Jeffery <andrew@...id.au>,
        openbmc@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org
Subject: Re: [PATCH v3] media: aspeed-video: ignore interrupts that aren't
 enabled

On Thu, 2021-06-17 at 17:02 -0500, Zev Weiss wrote:
> As partially addressed in commit 65d270acb2d6 ("media: aspeed: clear
> garbage interrupts"), the ASpeed video engine sometimes asserts
> interrupts that the driver hasn't enabled.  In addition to the
> CAPTURE_COMPLETE and FRAME_COMPLETE interrupts dealt with in that
> patch, COMP_READY has also been observed.  Instead of playing
> whack-a-mole with each one individually, we can instead just blanket
> ignore everything we haven't explicitly enabled.

Suspect this will fix an intermittent problem on AST2500 with
screensaver. Change looks good, thanks!

Reviewed-by: Eddie James <eajames@...ux.ibm.com>

> 
> Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
> ---
> 
> Changes since v2 [1]:
>  - minor commit message improvements
> 
> Changes since v1 [0]:
>  - dropped error message
>  - switched to a blanket-ignore approach as suggested by Ryan
> 
> [0] 
> https://lore.kernel.org/linux-arm-kernel/20201215024542.18888-1-zev@bewilderbeest.net/
> [1] 
> https://lore.kernel.org/openbmc/20210506234048.3214-1-zev@bewilderbeest.net/
> 
>  drivers/media/platform/aspeed-video.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/media/platform/aspeed-video.c
> b/drivers/media/platform/aspeed-video.c
> index 7bb6babdcade..77611c296a25 100644
> --- a/drivers/media/platform/aspeed-video.c
> +++ b/drivers/media/platform/aspeed-video.c
> @@ -563,6 +563,12 @@ static irqreturn_t aspeed_video_irq(int irq,
> void *arg)
>  	struct aspeed_video *video = arg;
>  	u32 sts = aspeed_video_read(video, VE_INTERRUPT_STATUS);
>  
> +	/*
> +	 * Hardware sometimes asserts interrupts that we haven't
> actually
> +	 * enabled; ignore them if so.
> +	 */
> +	sts &= aspeed_video_read(video, VE_INTERRUPT_CTRL);
> +
>  	/*
>  	 * Resolution changed or signal was lost; reset the engine and
>  	 * re-initialize
> @@ -629,16 +635,6 @@ static irqreturn_t aspeed_video_irq(int irq,
> void *arg)
>  			aspeed_video_start_frame(video);
>  	}
>  
> -	/*
> -	 * CAPTURE_COMPLETE and FRAME_COMPLETE interrupts come even
> when these
> -	 * are disabled in the VE_INTERRUPT_CTRL register so clear them
> to
> -	 * prevent unnecessary interrupt calls.
> -	 */
> -	if (sts & VE_INTERRUPT_CAPTURE_COMPLETE)
> -		sts &= ~VE_INTERRUPT_CAPTURE_COMPLETE;
> -	if (sts & VE_INTERRUPT_FRAME_COMPLETE)
> -		sts &= ~VE_INTERRUPT_FRAME_COMPLETE;
> -
>  	return sts ? IRQ_NONE : IRQ_HANDLED;
>  }
>