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

[Robin Murphy <robin.murphy@arm.com>]

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);
>