Re: [PATCH] media: v4l2-subdev: Refactor events
From: Sakari Ailus
Date: Sun Oct 20 2024 - 06:46:19 EST
Hi Tommaso,
On Sun, Oct 20, 2024 at 12:07:19AM +0200, Tommaso Merciai wrote:
> Hi Sakari,
>
> On Fri, Oct 18, 2024 at 07:30:30PM +0000, Sakari Ailus wrote:
> > Hi Tommaso,
> >
> > Thanks for working on this.
>
> In real it's a Laurent's suggestion :)
>
> >
> > On Fri, Oct 18, 2024 at 07:11:03PM +0200, Tommaso Merciai wrote:
> > > Controls can be exposed to userspace via a v4l-subdevX device, and
> > > userspace has to be able to subscribe to control events so that it is
> > > notified when the control changes value.
> > > If a control handler is set for the subdev then set the HAS_EVENTS
> > > flag automatically into v4l2_subdev_init_finalize() and use
> > > v4l2_ctrl_subdev_subscribe_event() and v4l2_event_subdev_unsubscribe()
> > > as default if subdev don't have .(un)subscribe control operations.
> > >
> > > Signed-off-by: Tommaso Merciai <tomm.merciai@xxxxxxxxx>
> > > ---
> > > drivers/media/v4l2-core/v4l2-subdev.c | 22 ++++++++++++++++++++--
> > > 1 file changed, 20 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > > index 3a4ba08810d2..77ca829b9983 100644
> > > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > > @@ -691,10 +691,25 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
> > > return v4l2_event_dequeue(vfh, arg, file->f_flags & O_NONBLOCK);
> > >
> > > case VIDIOC_SUBSCRIBE_EVENT:
> > > - return v4l2_subdev_call(sd, core, subscribe_event, vfh, arg);
> > > + if (v4l2_subdev_has_op(sd, core, subscribe_event))
> > > + return v4l2_subdev_call(sd, core, subscribe_event,
> > > + vfh, arg);
> > > +
> > > + if ((sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS) &&
> > > + vfh->ctrl_handler)
> > > + return v4l2_ctrl_subdev_subscribe_event(sd, vfh, arg);
> > > +
> > > + return -ENOIOCTLCMD;
> >
> > While this mostly does the same thing, I prefer the order of tests below.
> > Could you align event subscription with unsubscription?
>
> What about:
>
> case VIDIOC_SUBSCRIBE_EVENT:
> if (!(sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS))
> return -ENOIOCTLCMD;
>
> if (v4l2_subdev_has_op(sd, core, subscribe_event))
> return v4l2_subdev_call(sd, core, subscribe_event,
> vfh, arg);
>
> if (!vfh->ctrl_handler)
> return -ENOTTY;
>
> return v4l2_ctrl_subdev_subscribe_event(sd, vfh, arg);
Oh, right. Actually the earlier unsubscription didn't always produce
correct results. I missed that. This is needlessly complicated at the
moment. So I'd do:
case VIDIOC_SUBSCRIBE_EVENT:
if (v4l2_subdev_has_op(sd, core, subscribe_event))
return v4l2_subdev_call(sd, core, subscribe_event,
vfh, arg);
return (sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS) &&
vfh->ctrl_handler ?
v4l2_ctrl_subdev_subscribe_event(sd, vfh, arg) :
-ENOIOCTLCMD;
case VIDIOC_UNSUBSCRIBE_EVENT:
if (v4l2_subdev_has_op(sd, core, unsubscribe_event))
return v4l2_subdev_call(sd, core, unsubscribe_event,
vfh, arg);
return sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS ?
v4l2_event_subdev_unsubscribe(sd, vfh, arg) :
-ENOIOCTLCMD;
>
> case VIDIOC_UNSUBSCRIBE_EVENT:
> if (!(sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS))
> return -ENOIOCTLCMD;
>
> if (v4l2_subdev_has_op(sd, core, unsubscribe_event))
> return v4l2_subdev_call(sd, core, unsubscribe_event,
> vfh, arg);
>
> return v4l2_event_subdev_unsubscribe(sd, vfh, arg);
>
> ?
>
> Thanks & Regards,
> Tommaso
>
> >
> > >
> > > case VIDIOC_UNSUBSCRIBE_EVENT:
> > > - return v4l2_subdev_call(sd, core, unsubscribe_event, vfh, arg);
> > > + if (!(sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS))
> > > + return -ENOIOCTLCMD;
> > > +
> > > + if (v4l2_subdev_has_op(sd, core, unsubscribe_event))
> > > + return v4l2_subdev_call(sd, core, unsubscribe_event,
> > > + vfh, arg);
> > > +
> > > + return v4l2_event_subdev_unsubscribe(sd, vfh, arg);
> > >
> > > #ifdef CONFIG_VIDEO_ADV_DEBUG
> > > case VIDIOC_DBG_G_REGISTER:
> > > @@ -1641,6 +1656,9 @@ int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
> > > }
> > > }
> > >
> > > + if (sd->ctrl_handler)
> > > + sd->flags |= V4L2_SUBDEV_FL_HAS_EVENTS;
> > > +
> > > state = __v4l2_subdev_state_alloc(sd, name, key);
> > > if (IS_ERR(state))
> > > return PTR_ERR(state);
> >
> > --
> > Kind regards,
> >
> > Sakari Ailus
--
Sakari Ailus