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Subject: Re: [PATCH v10 21/21] media: uvcvideo: Return -EACCES to inactive
 controls
To:     Ricardo Ribalda <ribalda@chromium.org>,
        Hans Verkuil <hverkuil@xs4all.nl>
Cc:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-media@vger.kernel.org, tfiga@chromium.org,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        linux-kernel@vger.kernel.org
References: <20210618122923.385938-1-ribalda@chromium.org>
 <20210618122923.385938-22-ribalda@chromium.org>
 <CANiDSCvNvJ_xyuqgvvFv6aZGSm=H-9=SeV6wp5C_0-acm+wC=A@mail.gmail.com>
From:   Hans Verkuil <hverkuil-cisco@xs4all.nl>
Message-ID: <820809c2-a564-8a79-c279-7570c3bcc801@xs4all.nl>
Date:   Fri, 25 Jun 2021 13:06:58 +0200
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On 25/06/2021 12:29, Ricardo Ribalda wrote:
> Hi Hans
> 
> Did you have some hardware that did not work fine without this patch?
> Am I remembering correctly?

Yes, that's correct. It's one of my webcams, but I can't remember which one
it is. You probably want me to test this v10?

Regards,

	Hans

> 
> Thanks!
> 
> On Fri, 18 Jun 2021 at 14:29, Ricardo Ribalda <ribalda@chromium.org> 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.
>>
>> Also make sure that query_v4l2_ctrl doesn't return an error.
>>
>> Suggested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
>> Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
>> ---
>>  drivers/media/usb/uvc/uvc_ctrl.c | 73 +++++++++++++++++++++-----------
>>  1 file changed, 49 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
>> index da44d5c0b9ad..4f80c06d3c43 100644
>> --- a/drivers/media/usb/uvc/uvc_ctrl.c
>> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
>> @@ -1104,13 +1104,36 @@ 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;
>>
>> @@ -1126,18 +1149,8 @@ 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;
>> -
>> -               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);
>> @@ -1660,25 +1673,37 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev,
>>         return 0;
>>  }
>>
>> -static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
>> -                                 struct v4l2_ext_controls *ctrls,
>> -                                 struct uvc_control *uvc_control)
>> +static int uvc_ctrl_commit_error(struct uvc_video_chain *chain,
>> +                                struct uvc_entity *entity,
>> +                                struct v4l2_ext_controls *ctrls,
>> +                                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;
>> +
>> +       /* We could not find the control that failed. */
>> +       if (i == ctrls->count)
>> +               return ret;
>> +
>> +       if (uvc_ctrl_is_inactive(chain, err_control, mapping))
>> +               return -EACCES;
>>
>> -       return ctrls->count;
>> +       return ret;
>>  }
>>
>>  int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
>> @@ -1701,8 +1726,8 @@ 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_ctrl_idx(entity, ctrls,
>> -                                                         err_ctrl);
>> +               ret = uvc_ctrl_commit_error(chain, entity, ctrls, err_ctrl,
>> +                                           ret);
>>         mutex_unlock(&chain->ctrl_mutex);
>>         return ret;
>>  }
>> --
>> 2.32.0.288.g62a8d224e6-goog
>>
> 
>