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

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Date:	Thu, 04 Sep 2014 23:29:42 +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,

Thank you for the patch.

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.
> 
> Signed-off-by: Vincent Palatin <vpalatin@...omium.org>

Small comment here, as Pawel has reviewed the previous version, you could have 
added his Reviewed-by tag to the patch.

> ---
> 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;

Nitpicking, I would use unsigned int instead of int here, as the value can't 
be negative (same comment for the next function).

If you're fine with that there's no need to resubmit, I can modify this when 
applying.

> +	__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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