[PATCH] rcar-vin: Limit NV12 availability to supported VIN channels only

[PATCH] rcar-vin: Limit NV12 availability to supported VIN channels only

[Niklas Söderlund]

When adding support for NV12 it was overlooked that the pixel format is
only supported on some VIN channels. Fix this by adding a check to only
accept NV12 on the supported channels (0, 1, 4, 5, 8, 9, 12 and 13).

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
---
 drivers/media/platform/rcar-vin/rcar-v4l2.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/rcar-vin/rcar-v4l2.c b/drivers/media/platform/rcar-vin/rcar-v4l2.c
index 9e2e63ffcc47acad..62d308a4ddaee82e 100644
--- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
+++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
@@ -76,7 +76,12 @@ const struct rvin_video_format *rvin_format_from_pixel(struct rvin_dev *vin,
 	if (vin->info->model == RCAR_M1 && pixelformat == V4L2_PIX_FMT_XBGR32)
 		return NULL;
 
-	if (pixelformat == V4L2_PIX_FMT_NV12 && !vin->info->nv12)
+	/*
+	 * If NV12 is supported it's only supported on some channels (0, 1, 4,
+	 * 5, 8, 9, 12 and 13).
+	 */
+	if (pixelformat == V4L2_PIX_FMT_NV12 &&
+	    (!vin->info->nv12 || BIT(vin->id) & 0xcccc))
 		return NULL;
 
 	for (i = 0; i < ARRAY_SIZE(rvin_formats); i++)
-- 
2.23.0

Re: [PATCH] rcar-vin: Limit NV12 availability to supported VIN channels only

[Geert Uytterhoeven]

Hi Niklas,

On Thu, Nov 7, 2019 at 12:25 AM Niklas Söderlund
<niklas.soderlund+renesas@ragnatech.se> wrote:
> When adding support for NV12 it was overlooked that the pixel format is
> only supported on some VIN channels. Fix this by adding a check to only
> accept NV12 on the supported channels (0, 1, 4, 5, 8, 9, 12 and 13).
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

Thanks for your patch!

> --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> @@ -76,7 +76,12 @@ const struct rvin_video_format *rvin_format_from_pixel(struct rvin_dev *vin,
>         if (vin->info->model == RCAR_M1 && pixelformat == V4L2_PIX_FMT_XBGR32)
>                 return NULL;
>
> -       if (pixelformat == V4L2_PIX_FMT_NV12 && !vin->info->nv12)
> +       /*
> +        * If NV12 is supported it's only supported on some channels (0, 1, 4,
> +        * 5, 8, 9, 12 and 13).

Is this true for all SoCs, or do you need a vin->info->model == RCAR_GEN3
check?

> +        */
> +       if (pixelformat == V4L2_PIX_FMT_NV12 &&
> +           (!vin->info->nv12 || BIT(vin->id) & 0xcccc))
>                 return NULL;

So 0xcccc = ~(BIT(0) | BIT(1) | BIT(4) | ...)?
What if you ever have an id larger than 15?
Wouldn't it be safer to check for !(BIT(vin->id) & 0x3333)?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] rcar-vin: Limit NV12 availability to supported VIN channels only

[Niklas Söderlund]

Hi Geert,

Thanks for your feedback.

On 2019-11-07 08:41:11 +0100, Geert Uytterhoeven wrote:
> Hi Niklas,
> 
> On Thu, Nov 7, 2019 at 12:25 AM Niklas Söderlund
> <niklas.soderlund+renesas@ragnatech.se> wrote:
> > When adding support for NV12 it was overlooked that the pixel format is
> > only supported on some VIN channels. Fix this by adding a check to only
> > accept NV12 on the supported channels (0, 1, 4, 5, 8, 9, 12 and 13).
> >
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> 
> Thanks for your patch!
> 
> > --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > @@ -76,7 +76,12 @@ const struct rvin_video_format *rvin_format_from_pixel(struct rvin_dev *vin,
> >         if (vin->info->model == RCAR_M1 && pixelformat == V4L2_PIX_FMT_XBGR32)
> >                 return NULL;
> >
> > -       if (pixelformat == V4L2_PIX_FMT_NV12 && !vin->info->nv12)
> > +       /*
> > +        * If NV12 is supported it's only supported on some channels (0, 1, 4,
> > +        * 5, 8, 9, 12 and 13).
> 
> Is this true for all SoCs, or do you need a vin->info->model == RCAR_GEN3
> check?

NV12 is only supported by most Gen3 SoCs, but no extra check is needed 
as vin->info->nv12 is only set for the Gen3 SoCs that can support NV12.

> 
> > +        */
> > +       if (pixelformat == V4L2_PIX_FMT_NV12 &&
> > +           (!vin->info->nv12 || BIT(vin->id) & 0xcccc))
> >                 return NULL;
> 
> So 0xcccc = ~(BIT(0) | BIT(1) | BIT(4) | ...)?

Yes.

> What if you ever have an id larger than 15?
> Wouldn't it be safer to check for !(BIT(vin->id) & 0x3333)?

There is no SoC with more then 16 VIN instances, today... Maybe your 
suggestion of the inverted check makes more sens. Will respin a v2.

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

-- 
Regards,
Niklas Söderlund

Re: [PATCH] rcar-vin: Limit NV12 availability to supported VIN channels only

[Geert Uytterhoeven]

Hi Niklas,

On Thu, Nov 7, 2019 at 8:47 AM Niklas Söderlund
<niklas.soderlund+renesas@ragnatech.se> wrote:
> On 2019-11-07 08:41:11 +0100, Geert Uytterhoeven wrote:
> > On Thu, Nov 7, 2019 at 12:25 AM Niklas Söderlund
> > <niklas.soderlund+renesas@ragnatech.se> wrote:
> > > When adding support for NV12 it was overlooked that the pixel format is
> > > only supported on some VIN channels. Fix this by adding a check to only
> > > accept NV12 on the supported channels (0, 1, 4, 5, 8, 9, 12 and 13).
> > >
> > > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> >
> > Thanks for your patch!
> >
> > > --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > > +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > > @@ -76,7 +76,12 @@ const struct rvin_video_format *rvin_format_from_pixel(struct rvin_dev *vin,
> > >         if (vin->info->model == RCAR_M1 && pixelformat == V4L2_PIX_FMT_XBGR32)
> > >                 return NULL;
> > >
> > > -       if (pixelformat == V4L2_PIX_FMT_NV12 && !vin->info->nv12)
> > > +       /*
> > > +        * If NV12 is supported it's only supported on some channels (0, 1, 4,
> > > +        * 5, 8, 9, 12 and 13).
> >
> > Is this true for all SoCs, or do you need a vin->info->model == RCAR_GEN3
> > check?
>
> NV12 is only supported by most Gen3 SoCs, but no extra check is needed
> as vin->info->nv12 is only set for the Gen3 SoCs that can support NV12.

Thanks, had missed the meaning of the vin->info->nv12 check.

> > > +        */
> > > +       if (pixelformat == V4L2_PIX_FMT_NV12 &&
> > > +           (!vin->info->nv12 || BIT(vin->id) & 0xcccc))
> > >                 return NULL;
> >
> > So 0xcccc = ~(BIT(0) | BIT(1) | BIT(4) | ...)?
>
> Yes.
>
> > What if you ever have an id larger than 15?
> > Wouldn't it be safer to check for !(BIT(vin->id) & 0x3333)?
>
> There is no SoC with more then 16 VIN instances, today... Maybe your
> suggestion of the inverted check makes more sens. Will respin a v2.

OK.  BTW, the code may look nicer if you start using a
"switch (pixelformat) { ... }" block to handle all special cases.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds