On Tue, Nov 27, 2018 at 8:29 AM Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx> wrote:
>
> On Mon, 2018-11-26 at 13:14 +0900, Tomasz Figa wrote:
> > Hi Ezequiel,
> >
> > On Sat, Nov 24, 2018 at 2:20 AM Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx> wrote:
> > > Make the core set the reserved fields to zero in
> > > v4l2_pix_format_mplane and v4l2_plane_pix_format structs,
> > > for _MPLANE queue types.
> > >
> > > Moving this to the core avoids having to do so in each
> > > and every driver.
> > >
> > > Suggested-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
> > > Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> > > ---
> > > drivers/media/v4l2-core/v4l2-ioctl.c | 51 ++++++++++++++++++++++++----
> > > 1 file changed, 45 insertions(+), 6 deletions(-)
> > >
> >
> > Thanks for the patch. Please see my comments inline.
> >
> > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > index 10b862dcbd86..3858fffc3e68 100644
> > > --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> > > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > @@ -1420,6 +1420,7 @@ static int v4l_g_fmt(const struct v4l2_ioctl_ops *ops,
> > > {
> > > struct v4l2_format *p = arg;
> > > int ret = check_fmt(file, p->type);
> > > + int i;
> > >
> > > if (ret)
> > > return ret;
> > > @@ -1458,7 +1459,13 @@ static int v4l_g_fmt(const struct v4l2_ioctl_ops *ops,
> > > p->fmt.pix.priv = V4L2_PIX_FMT_PRIV_MAGIC;
> > > return ret;
> > > case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
> > > - return ops->vidioc_g_fmt_vid_cap_mplane(file, fh, arg);
> > > + ret = ops->vidioc_g_fmt_vid_cap_mplane(file, fh, arg);
> > > + memset(p->fmt.pix_mp.reserved, 0,
> > > + sizeof(p->fmt.pix_mp.reserved));
> > > + for (i = 0; i < p->fmt.pix_mp.num_planes; i++)
> > > + memset(p->fmt.pix_mp.plane_fmt[i].reserved, 0,
> > > + sizeof(p->fmt.pix_mp.plane_fmt[i].reserved));
> > > + return ret;
> > > case V4L2_BUF_TYPE_VIDEO_OVERLAY:
> > > return ops->vidioc_g_fmt_vid_overlay(file, fh, arg);
> > > case V4L2_BUF_TYPE_VBI_CAPTURE:
> > > @@ -1474,7 +1481,13 @@ static int v4l_g_fmt(const struct v4l2_ioctl_ops *ops,
> > > p->fmt.pix.priv = V4L2_PIX_FMT_PRIV_MAGIC;
> > > return ret;
> > > case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
> > > - return ops->vidioc_g_fmt_vid_out_mplane(file, fh, arg);
> > > + ret = ops->vidioc_g_fmt_vid_out_mplane(file, fh, arg);
> > > + memset(p->fmt.pix_mp.reserved, 0,
> > > + sizeof(p->fmt.pix_mp.reserved));
> > > + for (i = 0; i < p->fmt.pix_mp.num_planes; i++)
> > > + memset(p->fmt.pix_mp.plane_fmt[i].reserved, 0,
> > > + sizeof(p->fmt.pix_mp.plane_fmt[i].reserved));
> > > + return ret;
> >
> > I wonder if we need this for G_FMT. The driver can just memset() the
> > whole struct itself and then just initialize the fields it cares
> > about, but actually in many cases the driver will just include an
> > instance of the pix_fmt(_mp) struct in its internal state (which has
> > the reserved fields already zeroed) and just copy it to the target
> > struct in the callback.
> >
>
> Perhaps in many cases, but from code inspection it seems not
> all of them (randomly opened vicodec & mtk-jpeg and both need
> a memset!).
>
> I'm thinkig it'd best to keep it this way for consistency
> and to avoid having the worry at all about this in the drivers.
I guess it makes sense indeed. The structure isn't terribly big, so
there shouldn't be any significant performance penalty I suppose.
Perhaps the next step would be to have someone clean up the existing drivers.
>
> Should we use CLEAR_AFTER_FIELD here as well?
>
I think so.
Best regards,
Tomasz
