From 39d53fcd39df81baf92cc74a0de40d5a1cbbd9bf Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Tue, 19 May 2009 15:08:03 +0200 Subject: uvcvideo: Start status polling on device open From: Laurent Pinchart Most UVC camera include an interrupt endpoint to report control value changes, video streaming errors and camera button events. The USB controller continuously polls the interrupt endpoint to retrieve such events. This prevents the device from being auto-suspended, and thus consumes power. Reporting video streaming errors don't make sense when the V4L2 device is closed. Control value changes are probably useless as well if nobody listens to the events, although caching will probably have to be completely disabled then. No polling is thus be required when /dev/videoX is not opened. To enable auto-suspend and save power do not poll the interrupt endpoint until the device is open. We lose the ability to detect button events if no application is using the camera. http://bugzilla.kernel.org/show_bug.cgi?id=11948 Priority: normal Signed-off-by: Laurent Pinchart --- linux/drivers/media/video/uvc/uvc_status.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) (limited to 'linux/drivers/media/video/uvc/uvc_status.c') diff --git a/linux/drivers/media/video/uvc/uvc_status.c b/linux/drivers/media/video/uvc/uvc_status.c index 1e1bda413..b05df63b4 100644 --- a/linux/drivers/media/video/uvc/uvc_status.c +++ b/linux/drivers/media/video/uvc/uvc_status.c @@ -206,7 +206,7 @@ int uvc_status_init(struct uvc_device *dev) dev->status, UVC_MAX_STATUS_SIZE, uvc_status_complete, dev, interval); - return usb_submit_urb(dev->int_urb, GFP_KERNEL); + return 0; } void uvc_status_cleanup(struct uvc_device *dev) @@ -217,15 +217,30 @@ void uvc_status_cleanup(struct uvc_device *dev) uvc_input_cleanup(dev); } -int uvc_status_suspend(struct uvc_device *dev) +int uvc_status_start(struct uvc_device *dev) +{ + if (dev->int_urb == NULL) + return 0; + + return usb_submit_urb(dev->int_urb, GFP_KERNEL); +} + +void uvc_status_stop(struct uvc_device *dev) { usb_kill_urb(dev->int_urb); +} + +int uvc_status_suspend(struct uvc_device *dev) +{ + if (atomic_read(&dev->users)) + usb_kill_urb(dev->int_urb); + return 0; } int uvc_status_resume(struct uvc_device *dev) { - if (dev->int_urb == NULL) + if (dev->int_urb == NULL || atomic_read(&dev->users) == 0) return 0; return usb_submit_urb(dev->int_urb, GFP_NOIO); -- cgit v1.2.3