The Linux UVC driver has long provided adequate performance capabilities for web-cams and low data rate video devices in Linux while resolutions were low.
Modern USB cameras are now capable of high data rates thanks to USB3 with 1080p, and even 4k capture resolutions supported. Cameras such as the Stereolabs ZED or the Logitech Brio can generate more data than an embedded ARM core is able to process on a single core, resulting in frame loss. A large part of this performance impact is from the requirement to ‘memcpy’ frames out from URB packets to destination frames. This unfortunate requirement is due to the UVC protocol allowing a variable length header, and thus it is not possible to provide the target frame buffers directly. Extra throughput is possible by moving the actual memcpy actions to a work queue, and moving the memcpy out of interrupt context and allowing work tasks to be scheduled across multiple cores. This series has been tested on both the ZED and Brio cameras on arm64 platforms, however due to the intrinsic changes in the driver I would like to see it tested with other devices and other platforms, so I'd appreciate if anyone can test this on a range of USB cameras. v2: - Fix up comments and issues raised by Guennadi Kieran Bingham (6): uvcvideo: Refactor URB descriptors uvcvideo: Convert decode functions to use new context structure uvcvideo: Protect queue internals with helper uvcvideo: queue: Simplify spin-lock usage uvcvideo: queue: Support asynchronous buffer handling uvcvideo: Move decode processing to process context drivers/media/usb/uvc/uvc_isight.c | 4 +- drivers/media/usb/uvc/uvc_queue.c | 114 ++++++++++++++---- drivers/media/usb/uvc/uvc_video.c | 189 ++++++++++++++++++++++-------- drivers/media/usb/uvc/uvcvideo.h | 56 +++++++-- 4 files changed, 285 insertions(+), 78 deletions(-) base-commit: 6f0e5fd39143a59c22d60e7befc4f33f22aeed2f -- git-series 0.9.1
