Prod...
Is this acceptable to go in?
Thanks
Will
On 13/03/14 12:38, William Manley wrote:
> The uvcvideo webcam driver exposes the v4l2 control "Exposure (Absolute)"
> which allows the user to control the exposure time of the webcam,
> essentially controlling the brightness of the received image. By default
> the webcam automatically adjusts the exposure time automatically but the
> if you set the control "Exposure, Auto"="Manual Mode" the user can fix
> the exposure time.
>
> Unfortunately it seems that the Logitech C920 has a firmware bug where
> it will forget that it's in manual mode temporarily during initialisation.
> This means that the camera doesn't respect the exposure time that the user
> requested if they request it before starting to stream video. They end up
> with a video stream which is either too bright or too dark and must reset
> the controls after video starts streaming.
>
> This patch introduces the quirk UVC_QUIRK_RESTORE_CTRLS_ON_INIT which
> causes the cached controls to be re-uploaded to the camera immediately
> after initialising the camera. This quirk is applied to the C920 to work
> around this camera bug.
>
> Changes since patch v1:
> * Introduce quirk so workaround is only applied to the C920.
>
> Signed-off-by: William Manley <w...@williammanley.net>
> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 2 +-
> drivers/media/usb/uvc/uvc_driver.c | 11 ++++++++++-
> drivers/media/usb/uvc/uvc_video.c | 6 ++++++
> drivers/media/usb/uvc/uvcvideo.h | 3 ++-
> 4 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c
> b/drivers/media/usb/uvc/uvc_ctrl.c
> index a2f4501..f72d7eb 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1795,7 +1795,7 @@ done:
> * - Handle restore order (Auto-Exposure Mode should be restored before
> * Exposure Time).
> */
> -int uvc_ctrl_resume_device(struct uvc_device *dev)
> +int uvc_ctrl_restore_values(struct uvc_device *dev)
> {
> struct uvc_control *ctrl;
> struct uvc_entity *entity;
> diff --git a/drivers/media/usb/uvc/uvc_driver.c
> b/drivers/media/usb/uvc/uvc_driver.c
> index c3bb250..d3a9c3b 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -1981,7 +1981,7 @@ static int __uvc_resume(struct usb_interface *intf, int
> reset)
> int ret = 0;
>
> if (reset) {
> - ret = uvc_ctrl_resume_device(dev);
> + ret = uvc_ctrl_restore_values(dev);
> if (ret < 0)
> return ret;
> }
> @@ -2156,6 +2156,15 @@ static struct usb_device_id uvc_ids[] = {
> .bInterfaceClass = USB_CLASS_VENDOR_SPEC,
> .bInterfaceSubClass = 1,
> .bInterfaceProtocol = 0 },
> + /* Logitech HD Pro Webcam C920 */
> + { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
> + | USB_DEVICE_ID_MATCH_INT_INFO,
> + .idVendor = 0x046d,
> + .idProduct = 0x082d,
> + .bInterfaceClass = USB_CLASS_VIDEO,
> + .bInterfaceSubClass = 1,
> + .bInterfaceProtocol = 0,
> + .driver_info = UVC_QUIRK_RESTORE_CTRLS_ON_INIT },
> /* Chicony CNF7129 (Asus EEE 100HE) */
> { .match_flags = USB_DEVICE_ID_MATCH_DEVICE
> | USB_DEVICE_ID_MATCH_INT_INFO,
> diff --git a/drivers/media/usb/uvc/uvc_video.c
> b/drivers/media/usb/uvc/uvc_video.c
> index 3394c34..85ff6b8 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -1660,6 +1660,12 @@ static int uvc_init_video(struct uvc_streaming
> *stream, gfp_t gfp_flags)
> }
> }
>
> + /* The Logitech C920 temporarily forgets that it should not be
> + adjusting Exposure Absolute during init so restore controls to
> + stored values. */
> + if (stream->dev->quirks & UVC_QUIRK_RESTORE_CTRLS_ON_INIT)
> + uvc_ctrl_restore_values(stream->dev);
> +
> return 0;
> }
>
> diff --git a/drivers/media/usb/uvc/uvcvideo.h
> b/drivers/media/usb/uvc/uvcvideo.h
> index 9e35982..0f54376 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -137,6 +137,7 @@
> #define UVC_QUIRK_FIX_BANDWIDTH 0x00000080
> #define UVC_QUIRK_PROBE_DEF 0x00000100
> #define UVC_QUIRK_RESTRICT_FRAME_RATE 0x00000200
> +#define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
>
> /* Format flags */
> #define UVC_FMT_FLAG_COMPRESSED 0x00000001
> @@ -676,7 +677,7 @@ extern int uvc_ctrl_add_mapping(struct uvc_video_chain
> *chain,
> const struct uvc_control_mapping *mapping);
> extern int uvc_ctrl_init_device(struct uvc_device *dev);
> extern void uvc_ctrl_cleanup_device(struct uvc_device *dev);
> -extern int uvc_ctrl_resume_device(struct uvc_device *dev);
> +extern int uvc_ctrl_restore_values(struct uvc_device *dev);
>
> extern int uvc_ctrl_begin(struct uvc_video_chain *chain);
> extern int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
>
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