Hi Troy On 03/01/18 21:13, Troy Kisky wrote: > On 1/3/2018 12:32 PM, Kieran Bingham wrote: >> From: Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx> >> >> 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. > > > I have a rather large patch that does provide frame buffers directly for bulk > cameras. It cannot be used with ISOC cameras. But it is currently for 4.1. > I'll be porting it to 4.9 in a few days if you'd like to see it. How did you get on with this porting activity? Is it possible to share any of this work with the mailing lists ? (If you have not ported to v4.9 - I think it would be useful even to post the v4.1 patch and we can look at what's needed for getting it ported to mainline) -- Regards Kieran > > BR > Troy > > >> >> 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. >> >> 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 | 115 ++++++++++++++---- >> drivers/media/usb/uvc/uvc_video.c | 191 ++++++++++++++++++++++-------- >> drivers/media/usb/uvc/uvcvideo.h | 56 +++++++-- >> 4 files changed, 289 insertions(+), 77 deletions(-) >> >> base-commit: 6f0e5fd39143a59c22d60e7befc4f33f22aeed2f >> >
