From: Vincent Palatin <vpalatin@chromium.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Pawel Osciak <posciak@chromium.org>,
Hans de Goede <hdegoede@redhat.com>,
"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Olof Johansson <olofj@chromium.org>,
Zach Kuznia <zork@chromium.org>,
Mauro Carvalho Chehab <m.chehab@samsung.com>
Subject: Re: [PATCH v2] V4L: uvcvideo: Add support for relative pan/tilt controls
Date: Tue, 8 Jul 2014 16:28:16 -0700 [thread overview]
Message-ID: <CAP_ceTxk=OE3UVhNKk+WV7EG3E9Z0cOH4tZBU210Awa15OOjgw@mail.gmail.com> (raw)
In-Reply-To: <8119752.rPOQIYa4Af@avalon>
On Wed, Jun 25, 2014 at 2:54 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hi Pawel,
>
> On Wednesday 25 June 2014 11:46:24 Pawel Osciak wrote:
>> On Tue, Jun 17, 2014 at 11:45 PM, Vincent Palatin wrote:
>> > Map V4L2_CID_TILT_RELATIVE and V4L2_CID_PAN_RELATIVE to the standard UVC
>> > CT_PANTILT_RELATIVE_CONTROL terminal control request.
>> >
>> > Tested by plugging a Logitech ConferenceCam C3000e USB camera
>> > and controlling pan/tilt from the userspace using the VIDIOC_S_CTRL ioctl.
>> > Verified that it can pan and tilt at the same time in both directions.
>> >
>> > Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
>> >
>> > Change-Id: I7b70b228e5c0126683f5f0be34ffd2807f5783dc
>> > ---
>> >
>> > Changes
>> > v2: fix control request name in description.
>>
>> The patch looks good, but I have a more general comment for everyone to
>> consider. This doesn't match the expected functionality of
>> controls V4L2_CID_PAN/TILT_RELATIVE. This is basically an on/off switch for
>> pan/tilt, which once enabled will keep going until turned off (or I'm
>> guessing until the maximum pan/tilt is reached), while the controls are
>> supposed to expose an ability to turn the camera by a specified amount.
>> Here the amount will also be ignored...
>
> I agree with you here, and this mismatch between the V4L and UVC controls is
> the reason why I haven't implemented relative pan/tilt support.
>
>> Given that this is a standard UVC control, perhaps we need new V4L2
>> controls for it, as I'm assuming we can't change the meaning of existing
>> controls?
>
> We could extend the meaning of the controls to cover the UVC behaviour in a
> device-specific fashion, but that would be confusing for applications, so new
> controls might be a better idea.
Ok, I will add another patch to create new V4L2_CID_PAN_SPEED /
V4L2_CID_TILT_SPEED controls.
--
Vincent
next prev parent reply other threads:[~2014-07-08 23:28 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-17 0:38 [PATCH] V4L: uvcvideo: Add support for relative pan/tilt controls Vincent Palatin
2014-06-17 6:12 ` Hans de Goede
2014-06-17 14:45 ` [PATCH v2] " Vincent Palatin
[not found] ` <CACHYQ-rSk6etrX8RXF4w7aA_LJ9nzGtfJMOjhBOg49BZ4gaWgw@mail.gmail.com>
2014-06-25 9:54 ` Laurent Pinchart
2014-07-08 23:28 ` Vincent Palatin [this message]
2014-07-08 23:49 ` [PATCH 1/2] [media] V4L: Add camera pan/tilt speed controls Vincent Palatin
2014-07-08 23:49 ` [PATCH 2/2] V4L: uvcvideo: Add support for " Vincent Palatin
2014-09-03 4:57 ` Pawel Osciak
2014-09-03 19:40 ` [PATCH v3 " Vincent Palatin
2014-09-04 0:37 ` Pawel Osciak
2014-09-04 0:47 ` [PATCH v4 " Vincent Palatin
2014-09-04 20:29 ` Laurent Pinchart
2014-10-06 20:41 ` Vincent Palatin
2014-10-06 21:05 ` [PATCH v5 " Vincent Palatin
2014-10-07 16:36 ` Laurent Pinchart
2014-10-07 16:41 ` Vincent Palatin
2014-09-04 20:35 ` [PATCH v4 " Laurent Pinchart
2014-10-06 20:44 ` Vincent Palatin
2014-07-31 17:22 ` [PATCH 1/2] [media] V4L: Add camera " Vincent Palatin
[not found] ` <CACHYQ-o0FWSSHRmNhQ+id2uvHHWqVzQXQpmu31_e4OmDeVd_CQ@mail.gmail.com>
2014-08-06 15:10 ` Vincent Palatin
2014-08-07 2:18 ` Pawel Osciak
2014-08-08 16:41 ` Vincent Palatin
2014-08-15 19:08 ` [PATCH v2 " Vincent Palatin
2014-09-03 4:54 ` Pawel Osciak
2014-09-03 19:35 ` Vincent Palatin
2014-09-03 19:38 ` [PATCH v3 " Vincent Palatin
2014-10-06 21:04 ` [PATCH v5 " Vincent Palatin
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