linux-kernel - Re: [PATCH 12/13] media: cec: extron-da-hd-4k-plus: don't use -1 as an error code

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Message-ID: <6df9ffa7-a55e-4ae4-a863-eb64834aef48@xs4all.nl>
Date: Wed, 16 Oct 2024 12:36:24 +0200
From: Hans Verkuil <hverkuil@...all.nl>
To: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH 12/13] media: cec: extron-da-hd-4k-plus: don't use -1 as
 an error code

On 16/10/2024 12:22, Mauro Carvalho Chehab wrote:
> The logic at get_edid_tag_location() returns either an offset
> or an error condition. However, the error condition uses a
> non-standard "-1" value.
> 
> Use instead -ENOENT to indicate that the tag was not found.
> 
> Fixes: 056f2821b631 ("media: cec: extron-da-hd-4k-plus: add the Extron DA HD 4K Plus CEC driver")

Not a fix, since it isn't broken. It is returning an offset, and -1 is used if it isn't
found. It's fine to change it to -ENOENT since the code calling it just checks if the
result > 0.

So it is a slight improvement of the code, but not a fix.

> Cc: stable@...r.kernel.org

So this isn't needed either.

Regards,

	Hans

> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> ---
>  .../cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c     | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c b/drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c
> index a526464af88c..7d03a36df5cf 100644
> --- a/drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c
> +++ b/drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c
> @@ -348,12 +348,12 @@ static int get_edid_tag_location(const u8 *edid, unsigned int size,
>  
>  	/* Return if not a CTA-861 extension block */
>  	if (size < 256 || edid[0] != 0x02 || edid[1] != 0x03)
> -		return -1;
> +		return -ENOENT;
>  
>  	/* search tag */
>  	d = edid[0x02] & 0x7f;
>  	if (d <= 4)
> -		return -1;
> +		return -ENOENT;
>  
>  	i = 0x04;
>  	end = 0x00 + d;
> @@ -371,7 +371,7 @@ static int get_edid_tag_location(const u8 *edid, unsigned int size,
>  			return offset + i;
>  		i += len + 1;
>  	} while (i < end);
> -	return -1;
> +	return -ENOENT;
>  }
>  
>  static void extron_edid_crc(u8 *edid)