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Message-ID: <CANiDSCu5jtm1gvS0j1QjPny5bfXa8DRKy9EdZ=xbo0i--8sMJQ@mail.gmail.com>
Date: Thu, 10 Jun 2021 20:40:15 +0200
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Hans Verkuil <hverkuil-cisco@...all.nl>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Linux Media Mailing List <linux-media@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Tomasz Figa <tfiga@...omium.org>
Subject: Re: [PATCH v9 16/22] media: uvcvideo: Return -EACCES to inactive controls
Hi Laurent
Thanks for your review!
On Thu, 10 Jun 2021 at 19:28, Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
> On Fri, Mar 26, 2021 at 10:58:34AM +0100, Ricardo Ribalda wrote:
> > If a control is inactive return -EACCES to let the userspace know that
> > the value will not be applied automatically when the control is active
> > again.
>
> Isn't the device supposed to stall the control set in that case, with
> the bRequestErrorCode set to "Wrong state", which uvc_query_ctrl()
> translates to -EACCES already ? Could you elaborate on why this patch is
> needed ?
The problem is that the hardware was not returning the equivalent of
EACCES, so we had to capture it manually.
I will try to revert the patch and capture an error.
>
> > Suggested-by: Hans Verkuil <hverkuil-cisco@...all.nl>
> > Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> > ---
> > drivers/media/usb/uvc/uvc_ctrl.c | 71 +++++++++++++++++++++-----------
> > 1 file changed, 48 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> > index bcebf9d1a46f..d9d4add1e813 100644
> > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> > @@ -1082,13 +1082,36 @@ static const char *uvc_map_get_name(const struct uvc_control_mapping *map)
> > return "Unknown Control";
> > }
> >
> > +static bool uvc_ctrl_is_inactive(struct uvc_video_chain *chain,
> > + struct uvc_control *ctrl,
> > + struct uvc_control_mapping *mapping)
> > +{
> > + struct uvc_control_mapping *master_map = NULL;
> > + struct uvc_control *master_ctrl = NULL;
> > + s32 val;
> > + int ret;
> > +
> > + if (!mapping->master_id)
> > + return false;
> > +
> > + __uvc_find_control(ctrl->entity, mapping->master_id, &master_map,
> > + &master_ctrl, 0);
> > +
> > + if (!master_ctrl || !(master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
> > + return false;
> > +
> > + ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
> > + if (ret < 0 || val == mapping->master_manual)
> > + return false;
> > +
> > + return true;
> > +}
> > +
> > static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> > struct uvc_control *ctrl,
> > struct uvc_control_mapping *mapping,
> > struct v4l2_queryctrl *v4l2_ctrl)
> > {
> > - struct uvc_control_mapping *master_map = NULL;
> > - struct uvc_control *master_ctrl = NULL;
> > const struct uvc_menu_info *menu;
> > unsigned int i;
> >
> > @@ -1104,18 +1127,8 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> > if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR))
> > v4l2_ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> >
> > - if (mapping->master_id)
> > - __uvc_find_control(ctrl->entity, mapping->master_id,
> > - &master_map, &master_ctrl, 0);
> > - if (master_ctrl && (master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR)) {
> > - s32 val;
> > - int ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
> > - if (ret < 0)
> > - return ret;
>
> There's a small change in behaviour here, the driver used to return an
> error, now it will ignore it. Is it intentional ?
AFAIK The error did not follow the v4l2 spec. You shall always be able
to query a ctrl.
I will add it to the commit message to make it clear.
>
> > -
> > - if (val != mapping->master_manual)
> > - v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
> > - }
> > + if (uvc_ctrl_is_inactive(chain, ctrl, mapping))
> > + v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
> >
> > if (!ctrl->cached) {
> > int ret = uvc_ctrl_populate_cache(chain, ctrl);
> > @@ -1638,25 +1651,37 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev,
> > return 0;
> > }
> >
> > -static int uvc_ctrl_find_ctrlidx(struct uvc_entity *entity,
> > +static int uvc_ctrl_commit_error(struct uvc_video_chain *chain,
> > + struct uvc_entity *entity,
> > struct v4l2_ext_controls *ctrls,
> > - struct uvc_control *uvc_control)
> > + struct uvc_control *err_control,
> > + int ret)
> > {
> > struct uvc_control_mapping *mapping;
> > struct uvc_control *ctrl_found;
> > unsigned int i;
> >
> > - if (!entity)
> > - return ctrls->count;
> > + if (!entity) {
> > + ctrls->error_idx = ctrls->count;
> > + return ret;
> > + }
> >
> > for (i = 0; i < ctrls->count; i++) {
> > __uvc_find_control(entity, ctrls->controls[i].id, &mapping,
> > &ctrl_found, 0);
> > - if (uvc_control == ctrl_found)
> > - return i;
> > + if (err_control == ctrl_found)
> > + break;
> > }
> > + ctrls->error_idx = i;
>
> I think this line should be moved after the next check.
Not really, if we cannot find a control, we cannot blame it on control 0 ;)
>
> > +
> > + /* We could not find the control that failed. */
> > + if (i == ctrls->count)
> > + return ret;
> >
> > - return ctrls->count;
> > + if (uvc_ctrl_is_inactive(chain, err_control, mapping))
> > + return -EACCES;
> > +
> > + return ret;
> > }
> >
> > int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
> > @@ -1679,8 +1704,8 @@ int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
> > uvc_ctrl_send_events(handle, ctrls->controls, ctrls->count);
> > done:
> > if (ret < 0 && ctrls)
> > - ctrls->error_idx = uvc_ctrl_find_ctrlidx(entity, ctrls,
> > - err_ctrl);
> > + ret = uvc_ctrl_commit_error(chain, entity, ctrls, err_ctrl,
> > + ret);
> > mutex_unlock(&chain->ctrl_mutex);
> > return ret;
> > }
>
> --
> Regards,
>
> Laurent Pinchart
--
Ricardo Ribalda
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