path: root/drivers/media/usb/uvc/uvc_driver.c
diff options
authorWilliam Manley <will@williammanley.net>2014-03-13 09:38:48 -0300
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2014-09-21 20:25:54 -0300
commit17e1319fd051f6f1d8b923ca3104c3391610ab32 (patch)
treed4facfa10f0749c190593ae251f310aa4a9e5b22 /drivers/media/usb/uvc/uvc_driver.c
parent3ea375239ca06014b8b421ab1d73d6628d22036f (diff)
[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 <will@williammanley.net> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Diffstat (limited to 'drivers/media/usb/uvc/uvc_driver.c')
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index f8135f4e3b52..51dfa74a81a9 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
+ .idVendor = 0x046d,
+ .idProduct = 0x082d,
+ .bInterfaceClass = USB_CLASS_VIDEO,
+ .bInterfaceSubClass = 1,
+ .bInterfaceProtocol = 0,
/* Chicony CNF7129 (Asus EEE 100HE) */

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