Re: [PATCH] media: rkvdec: silence ktest bot build warning

From: Boris Brezillon
Date: Thu Jan 07 2021 - 06:42:37 EST


On Thu, 7 Jan 2021 10:13:43 +0100
Hans Verkuil <hverkuil@xxxxxxxxx> wrote:

> On 08/12/2020 16:55, Adrian Ratiu wrote:
> > Some configurations built by the ktest bot produce the following
> > warn, so mark the struct as __maybe_unused to avoid unnecessary
> > ML spam.
> >
> >>> drivers/staging/media/rkvdec/rkvdec.c:967:34: warning: unused variable 'of_rkvdec_match' [-Wunused-const-variable]
> > static const struct of_device_id of_rkvdec_match[] = {
> > ^
> > 1 warning generated.
>
> I suspect that this is because there is no 'depends on OF' in the Kconfig.
>
> '__maybe_unused' isn't used for this anywhere else, so this does not seem like the
> right approach.

It's not uncommon to do that, especially when you want the driver to be
compile-tested (`git grep -C2 __maybe_unused|grep of_device_id` even
reports 2 drivers in the media tree :P). A `depends on OF` or an
`#ifdef CONFIG_OF` section surrounding the of_rkvdec_match declaration
would also do the trick.

>
> Regards,
>
> Hans
>
> >
> > vim +/of_rkvdec_match +967 drivers/staging/media/rkvdec/rkvdec.c
> >
> > 966
> > > 967 static const struct of_device_id of_rkvdec_match[] = {
> > 968 { .compatible = "rockchip,rk3399-vdec" },
> > 969 { /* sentinel */ }
> > 970 };
> > 971 MODULE_DEVICE_TABLE(of, of_rkvdec_match);
> > 972
> >
> > Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> > Cc: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> > Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Signed-off-by: Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx>
> > ---
> > drivers/staging/media/rkvdec/rkvdec.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/staging/media/rkvdec/rkvdec.c b/drivers/staging/media/rkvdec/rkvdec.c
> > index aa4f8c287618..3af0f02ec59b 100644
> > --- a/drivers/staging/media/rkvdec/rkvdec.c
> > +++ b/drivers/staging/media/rkvdec/rkvdec.c
> > @@ -992,7 +992,7 @@ static void rkvdec_watchdog_func(struct work_struct *work)
> > }
> > }
> >
> > -static const struct of_device_id of_rkvdec_match[] = {
> > +static const struct of_device_id __maybe_unused of_rkvdec_match[] = {
> > { .compatible = "rockchip,rk3399-vdec" },
> > { /* sentinel */ }
> > };
> >
>