[PATCH] media: hantro: fix compatible string deprecation warning

[PATCH] media: hantro: fix compatible string deprecation warning

[Martin Kepplinger]

of_device_is_compatible() in the end uses strlen of the string
for comparison, so in this case, the condition is true even if
the requested string "nxp,imx8mq-vpu-g1" is being used. The first
chars containing "nxp,imx8mq-vpu" are the same.

Fix this by encoding what the comment says.

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
---

This is more of a bugreport as the solution doesn't look very elegant
to me. I'm happy for advice.

thanks,
                           martin


 drivers/staging/media/hantro/hantro_drv.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c
index ac232b5f7825..014fab637df0 100644
--- a/drivers/staging/media/hantro/hantro_drv.c
+++ b/drivers/staging/media/hantro/hantro_drv.c
@@ -923,10 +923,11 @@ static int hantro_probe(struct platform_device *pdev)
 
 	/*
 	 * Support for nxp,imx8mq-vpu is kept for backwards compatibility
-	 * but it's deprecated. Please update your DTS file to use
-	 * nxp,imx8mq-vpu-g1 or nxp,imx8mq-vpu-g2 instead.
+	 * but it's deprecated.
 	 */
-	if (of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu"))
+	if ((of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu")) &&
+	    (!of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu-g1")) &&
+	    (!of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu-g2")))
 		dev_warn(&pdev->dev, "%s compatible is deprecated\n",
 			 match->compatible);
 
-- 
2.30.2

Re: [PATCH] media: hantro: fix compatible string deprecation warning

[Robin Murphy]

On 2022-05-17 15:35, Martin Kepplinger wrote:
> of_device_is_compatible() in the end uses strlen of the string
> for comparison, so in this case, the condition is true even if
> the requested string "nxp,imx8mq-vpu-g1" is being used. The first
> chars containing "nxp,imx8mq-vpu" are the same.

Have you seen this go wrong in practice? AFAICS, unless you're on SPARC, 
which seems somewhat unlikely for an i.MX8 peripheral, of_compat_cmp() 
should map to strcasecmp(), which should do the right thing :/

Robin.

> Fix this by encoding what the comment says.
> 
> Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
> ---
> 
> This is more of a bugreport as the solution doesn't look very elegant
> to me. I'm happy for advice.
> 
> thanks,
>                             martin
> 
> 
>   drivers/staging/media/hantro/hantro_drv.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c
> index ac232b5f7825..014fab637df0 100644
> --- a/drivers/staging/media/hantro/hantro_drv.c
> +++ b/drivers/staging/media/hantro/hantro_drv.c
> @@ -923,10 +923,11 @@ static int hantro_probe(struct platform_device *pdev)
>   
>   	/*
>   	 * Support for nxp,imx8mq-vpu is kept for backwards compatibility
> -	 * but it's deprecated. Please update your DTS file to use
> -	 * nxp,imx8mq-vpu-g1 or nxp,imx8mq-vpu-g2 instead.
> +	 * but it's deprecated.
>   	 */
> -	if (of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu"))
> +	if ((of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu")) &&
> +	    (!of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu-g1")) &&
> +	    (!of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu-g2")))
>   		dev_warn(&pdev->dev, "%s compatible is deprecated\n",
>   			 match->compatible);
>   

Re: [PATCH] media: hantro: fix compatible string deprecation warning

[Hans Verkuil]

Hi Martin,

On 5/17/22 18:46, Robin Murphy wrote:
> On 2022-05-17 15:35, Martin Kepplinger wrote:
>> of_device_is_compatible() in the end uses strlen of the string
>> for comparison, so in this case, the condition is true even if
>> the requested string "nxp,imx8mq-vpu-g1" is being used. The first
>> chars containing "nxp,imx8mq-vpu" are the same.
> 
> Have you seen this go wrong in practice? AFAICS, unless you're on SPARC, which seems somewhat unlikely for an i.MX8 peripheral, of_compat_cmp() should map to strcasecmp(), which should do the right thing :/

Robin is correct, the existing code is fine for all but SPARC, which
won't be using this driver.

I'm rejecting this patch.

Regards,

	Hans

> 
> Robin.
> 
>> Fix this by encoding what the comment says.
>>
>> Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
>> ---
>>
>> This is more of a bugreport as the solution doesn't look very elegant
>> to me. I'm happy for advice.
>>
>> thanks,
>>                             martin
>>
>>
>>   drivers/staging/media/hantro/hantro_drv.c | 7 ++++---
>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c
>> index ac232b5f7825..014fab637df0 100644
>> --- a/drivers/staging/media/hantro/hantro_drv.c
>> +++ b/drivers/staging/media/hantro/hantro_drv.c
>> @@ -923,10 +923,11 @@ static int hantro_probe(struct platform_device *pdev)
>>         /*
>>        * Support for nxp,imx8mq-vpu is kept for backwards compatibility
>> -     * but it's deprecated. Please update your DTS file to use
>> -     * nxp,imx8mq-vpu-g1 or nxp,imx8mq-vpu-g2 instead.
>> +     * but it's deprecated.
>>        */
>> -    if (of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu"))
>> +    if ((of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu")) &&
>> +        (!of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu-g1")) &&
>> +        (!of_device_is_compatible(pdev->dev.of_node, "nxp,imx8mq-vpu-g2")))
>>           dev_warn(&pdev->dev, "%s compatible is deprecated\n",
>>                match->compatible);
>>