From 17e1319fd051f6f1d8b923ca3104c3391610ab32 Mon Sep 17 00:00:00 2001 From: William Manley Date: Thu, 13 Mar 2014 09:38:48 -0300 Subject: [PATCH] [media] uvcvideo: Work around buggy Logitech C920 firmware 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. Signed-off-by: William Manley Signed-off-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab --- 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 d2d1755145c..3e59b288b8a 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -1847,7 +1847,7 @@ 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 f8135f4e3b5..51dfa74a81a 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -2000,7 +2000,7 @@ 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; } @@ -2175,6 +2175,15 @@ 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 7e350d788fe..a2bddf48171 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -1678,6 +1678,12 @@ 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 b1f69a6d406..39c4f941b63 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -147,6 +147,7 @@ #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 @@ -688,7 +689,7 @@ 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, -- 2.46.0