linux-kernel - Re: [PATCH v4 2/2] V4L: uvcvideo: Add support for pan/tilt speed controls

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Message-ID: <3751957.rA6PG2ReCf@avalon>
Date:	Thu, 04 Sep 2014 23:35:25 +0300
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Vincent Palatin <vpalatin@...omium.org>
Cc:	Hans de Goede <hdegoede@...hat.com>,
	Pawel Osciak <posciak@...omium.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	Olof Johansson <olofj@...omium.org>,
	Zach Kuznia <zork@...omium.org>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>
Subject: Re: [PATCH v4 2/2] V4L: uvcvideo: Add support for pan/tilt speed controls

Hi Vincent,

On Wednesday 03 September 2014 17:47:48 Vincent Palatin wrote:
> Map V4L2_CID_TILT_SPEED and V4L2_CID_PAN_SPEED 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.

By the way, what is the control value reported by the device after it stops 
moving by itself due to reaching a limit position ?

> Signed-off-by: Vincent Palatin <vpalatin@...omium.org>
> ---
> Changes from v1/v2:
> - rebased
> Changes from v3:
> - removed gerrit-id
> 
>  drivers/media/usb/uvc/uvc_ctrl.c | 58 ++++++++++++++++++++++++++++++++++---
>  1 file changed, 55 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c
> b/drivers/media/usb/uvc/uvc_ctrl.c index 0eb82106..d703cb0 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -309,9 +309,8 @@ static struct uvc_control_info uvc_ctrls[] = {
>  		.selector	= UVC_CT_PANTILT_RELATIVE_CONTROL,
>  		.index		= 12,
>  		.size		= 4,
> -		.flags		= UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_MIN
> -				| UVC_CTRL_FLAG_GET_MAX | UVC_CTRL_FLAG_GET_RES
> -				| UVC_CTRL_FLAG_GET_DEF
> +		.flags		= UVC_CTRL_FLAG_SET_CUR
> +				| UVC_CTRL_FLAG_GET_RANGE
> 
>  				| UVC_CTRL_FLAG_AUTO_UPDATE,
> 
>  	},
>  	{
> @@ -391,6 +390,35 @@ static void uvc_ctrl_set_zoom(struct
> uvc_control_mapping *mapping, data[2] = min((int)abs(value), 0xff);
>  }
> 
> +static __s32 uvc_ctrl_get_rel_speed(struct uvc_control_mapping *mapping,
> +	__u8 query, const __u8 *data)
> +{
> +	int first = mapping->offset / 8;
> +	__s8 rel = (__s8)data[first];
> +
> +	switch (query) {
> +	case UVC_GET_CUR:
> +		return (rel == 0) ? 0 : (rel > 0 ? data[first+1]
> +						 : -data[first+1]);
> +	case UVC_GET_MIN:
> +		return -data[first+1];
> +	case UVC_GET_MAX:
> +	case UVC_GET_RES:
> +	case UVC_GET_DEF:
> +	default:
> +		return data[first+1];
> +	}
> +}
> +
> +static void uvc_ctrl_set_rel_speed(struct uvc_control_mapping *mapping,
> +	__s32 value, __u8 *data)
> +{
> +	int first = mapping->offset / 8;
> +
> +	data[first] = value == 0 ? 0 : (value > 0) ? 1 : 0xff;
> +	data[first+1] = min_t(int, abs(value), 0xff);
> +}
> +
>  static struct uvc_control_mapping uvc_ctrl_mappings[] = {
>  	{
>  		.id		= V4L2_CID_BRIGHTNESS,
> @@ -677,6 +705,30 @@ static struct uvc_control_mapping uvc_ctrl_mappings[] =
> { .data_type	= UVC_CTRL_DATA_TYPE_SIGNED,
>  	},
>  	{
> +		.id		= V4L2_CID_PAN_SPEED,
> +		.name		= "Pan (Speed)",
> +		.entity		= UVC_GUID_UVC_CAMERA,
> +		.selector	= UVC_CT_PANTILT_RELATIVE_CONTROL,
> +		.size		= 16,
> +		.offset		= 0,
> +		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
> +		.data_type	= UVC_CTRL_DATA_TYPE_SIGNED,
> +		.get		= uvc_ctrl_get_rel_speed,
> +		.set		= uvc_ctrl_set_rel_speed,
> +	},
> +	{
> +		.id		= V4L2_CID_TILT_SPEED,
> +		.name		= "Tilt (Speed)",
> +		.entity		= UVC_GUID_UVC_CAMERA,
> +		.selector	= UVC_CT_PANTILT_RELATIVE_CONTROL,
> +		.size		= 16,
> +		.offset		= 16,
> +		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
> +		.data_type	= UVC_CTRL_DATA_TYPE_SIGNED,
> +		.get		= uvc_ctrl_get_rel_speed,
> +		.set		= uvc_ctrl_set_rel_speed,
> +	},
> +	{
>  		.id		= V4L2_CID_PRIVACY,
>  		.name		= "Privacy",
>  		.entity		= UVC_GUID_UVC_CAMERA,

-- 
Regards,

Laurent Pinchart

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