linux-kernel - Re: [PATCH 1/6] media: v4l2-subdev: stub v4l2_subdev_get_try

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Date:   Tue, 04 Dec 2018 16:01:43 +0100
From:   Lubomir Rintel <lkundrak@...sk>
To:     jacopo mondi <jacopo@...ndi.org>
Cc:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rui Miguel Silva <rmfrfs@...il.com>,
        Shunqian Zheng <zhengsq@...k-chips.com>,
        Jonathan Corbet <corbet@....net>,
        Wenyou Yang <wenyou.yang@...rochip.com>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] media: v4l2-subdev: stub
 v4l2_subdev_get_try_format() ..

On Mon, 2018-12-03 at 14:48 +0100, jacopo mondi wrote:
> Hi Lubomir,
> 
>   thanks for the patches
> 
> On Wed, Nov 28, 2018 at 06:19:13PM +0100, Lubomir Rintel wrote:
> > Provide a dummy implementation when configured without
> > CONFIG_VIDEO_V4L2_SUBDEV_API to avoid ifdef dance in the drivers
> > that can
> > be built either with or without the option.
> > 
> > Suggested-by: Jacopo Mondi <jacopo@...ndi.org>
> > Signed-off-by: Lubomir Rintel <lkundrak@...sk>
> > ---
> >  include/media/v4l2-subdev.h | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-
> > subdev.h
> > index 9102d6ca566e..906e28011bb4 100644
> > --- a/include/media/v4l2-subdev.h
> > +++ b/include/media/v4l2-subdev.h
> > @@ -967,6 +967,17 @@ static inline struct v4l2_rect
> >  		pad = 0;
> >  	return &cfg[pad].try_compose;
> >  }
> > +
> > +#else /* !defined(CONFIG_VIDEO_V4L2_SUBDEV_API) */
> > +
> > +static inline struct v4l2_mbus_framefmt
> > +*v4l2_subdev_get_try_format(struct v4l2_subdev *sd,
> > +			    struct v4l2_subdev_pad_config *cfg,
> > +			    unsigned int pad)
> > +{
> > +	return ERR_PTR(-ENOTTY);
> > +}
> > +
> >  #endif
> 
> While at there, what about doing the same for get_try_crop and
> get_try_compose? At lease provide stubs, I let you figure out if
> you're willing to fix callers too, it seems there are quite a few of
> them though
> 
> $ git grep v4l2_subdev_get_try* drivers/media/ | grep -v '_format' |
> wc -l
> 44

I'd be happy to do that. However, the drivers that use those seem to
depend on CONFIG_VIDEO_V4L2_SUBDEV_API anyway. Should those
dependencies be eventually done away with?

Please pardon my ignorance -- I don't actually understand why would
anyone disable CONFIG_VIDEO_V4L2_SUBDEV_API.

I'll be following up with a v2 after I get a response from you. It will
address locking issues found with smatch: one introduced by my patch
and one that was there before.

Cheers,
Lubo

> >  extern const struct v4l2_file_operations v4l2_subdev_fops;
> > --
> > 2.19.1
> >