linux-kernel - Re: [PATCH v7 15/17] media: uvcvideo: Refactor __uvc_ctrl

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Date:   Fri, 19 Mar 2021 16:01:03 +0100
From:   Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>
Cc:     Ricardo Ribalda <ribalda@...omium.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-media <linux-media@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Tomasz Figa <tfiga@...omium.org>
Subject: Re: [PATCH v7 15/17] media: uvcvideo: Refactor __uvc_ctrl_commit

Hello Hans


On Fri, Mar 19, 2021 at 9:35 AM Hans Verkuil <hverkuil-cisco@...all.nl> wrote:
>
> On 18/03/2021 21:29, Ricardo Ribalda wrote:
> > Take a v4l2_ext_controls instead of an array of controls, this way we
> > can access the error_idx in future changes.
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> > ---
> >  drivers/media/usb/uvc/uvc_ctrl.c |  5 ++---
> >  drivers/media/usb/uvc/uvc_v4l2.c |  8 ++++++--
> >  drivers/media/usb/uvc/uvcvideo.h | 10 ++++------
> >  3 files changed, 12 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> > index 1ec8333811bc..fb8155ca0c0d 100644
> > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> > @@ -1664,8 +1664,7 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev,
> >  }
> >
> >  int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
> > -                   const struct v4l2_ext_control *xctrls,
> > -                   unsigned int xctrls_count)
> > +                   struct v4l2_ext_controls *ctrls)
> >  {
> >       struct uvc_video_chain *chain = handle->chain;
> >       struct uvc_entity *entity;
> > @@ -1679,7 +1678,7 @@ int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
> >       }
> >
> >       if (!rollback)
> > -             uvc_ctrl_send_events(handle, xctrls, xctrls_count);
> > +             uvc_ctrl_send_events(handle, ctrls->controls, ctrls->count);
> >  done:
> >       mutex_unlock(&chain->ctrl_mutex);
> >       return ret;
> > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> > index ddebdeb5a81b..ea2c41b04664 100644
> > --- a/drivers/media/usb/uvc/uvc_v4l2.c
> > +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> > @@ -1025,6 +1025,10 @@ static int uvc_ioctl_s_ctrl(struct file *file, void *fh,
> >       struct uvc_fh *handle = fh;
> >       struct uvc_video_chain *chain = handle->chain;
> >       struct v4l2_ext_control xctrl;
> > +     struct v4l2_ext_controls ctrls = {
> > +             .count = 1,
> > +             .controls = &xctrl,
> > +     };
>
> Rather than creating this extra ctrls struct, I think this can be simplified by just
> removing uvc_ioctl_s_ctrl and uvc_ioctl_g_ctrl altogether. The v4l2-ioctl.c source
> will call vidioc_g/s_ext_ctrls if the driver doesn't provide vidioc_g/s_ctrl ops.
>
> Let's just simplify this by adding another patch before this one that just removes
> uvc_ioctl_s_ctrl and uvc_ioctl_g_ctrl.
>
> Otherwise this patch looks good.

I think I have found a 13 year old bug.....
https://git.kernel.org/pub/scm/linux/kernel/git/ribalda/linux.git/commit/?h=uvc-compliance-v8&id=7034e9ed5a8203c73cef9ab972ece48ade70b22f

>
> Regards,
>
>         Hans
>
> >       int ret;
> >
> >       ret = uvc_ctrl_is_accessible(chain, ctrl->id, VIDIOC_S_CTRL);
> > @@ -1045,7 +1049,7 @@ static int uvc_ioctl_s_ctrl(struct file *file, void *fh,
> >               return ret;
> >       }
> >
> > -     ret = uvc_ctrl_commit(handle, &xctrl, 1);
> > +     ret = uvc_ctrl_commit(handle, &ctrls);
> >       if (ret < 0)
> >               return ret;
> >
> > @@ -1149,7 +1153,7 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
> >       ctrls->error_idx = 0;
> >
> >       if (ioctl == VIDIOC_S_EXT_CTRLS)
> > -             return uvc_ctrl_commit(handle, ctrls->controls, ctrls->count);
> > +             return uvc_ctrl_commit(handle, ctrls);
> >       else
> >               return uvc_ctrl_rollback(handle);
> >  }
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index a93aeedb5499..4e7b6da3c6d2 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -887,17 +887,15 @@ void uvc_ctrl_status_event(struct uvc_video_chain *chain,
> >
> >  int uvc_ctrl_begin(struct uvc_video_chain *chain);
> >  int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
> > -                   const struct v4l2_ext_control *xctrls,
> > -                   unsigned int xctrls_count);
> > +                   struct v4l2_ext_controls *ctrls);
> >  static inline int uvc_ctrl_commit(struct uvc_fh *handle,
> > -                               const struct v4l2_ext_control *xctrls,
> > -                               unsigned int xctrls_count)
> > +                               struct v4l2_ext_controls *ctrls)
> >  {
> > -     return __uvc_ctrl_commit(handle, 0, xctrls, xctrls_count);
> > +     return __uvc_ctrl_commit(handle, 0, ctrls);
> >  }
> >  static inline int uvc_ctrl_rollback(struct uvc_fh *handle)
> >  {
> > -     return __uvc_ctrl_commit(handle, 1, NULL, 0);
> > +     return __uvc_ctrl_commit(handle, 1, NULL);
> >  }
> >
> >  int uvc_ctrl_get(struct uvc_video_chain *chain, struct v4l2_ext_control *xctrl);
> >
>


-- 
Ricardo Ribalda