Re: [PATCH v4 0/6] Asynchronous UVC

[Mauro Carvalho Chehab <mchehab+samsung@kernel.org>]

Em Tue, 27 Mar 2018 17:45:57 +0100
Kieran Bingham <kieran.bingham@ideasonboard.com> escreveu:

> 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 (bulk transfers) or the Logitech BRIO
> (isochronous transfers) 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 thus allowing work tasks
> to be scheduled across multiple cores.
> 
> This series has been tested on both the ZED and BRIO cameras on arm64
> platforms, and with thanks to Randy Dunlap, a Dynex 1.3MP Webcam, a Sonix USB2
> Camera, and a built in Toshiba Laptop camera, and with thanks to Philipp Zabel
> for testing on a Lite-On internal Laptop Webcam, Logitech C910 (USB2 isoc),
> Oculus Sensor (USB3 isoc), and Microsoft HoloLens Sensors (USB3 bulk).
> 
> As far as I am aware iSight devices, and devices which use UVC to encode data
> (output device) have not yet been tested - but should find no ill effect (at
> least not until they are tested of course :D )
> 
> Tested-by: Randy Dunlap <rdunlap@infradead.org>
> Tested-by: Philipp Zabel <philipp.zabel@gmail.com>
> 
> v2:
>  - Fix race reported by Guennadi
> 
> v3:
>  - Fix similar race reported by Laurent
>  - Only queue work if required (encode/isight do not queue work)
>  - Refactor/Rename variables for clarity
> 
> v4:
>  - (Yet another) Rework of the uninitialise path.
>    This time to hopefully clean up the shutdown races for good.
>    use usb_poison_urb() to halt all URBs, then flush the work queue
>    before freeing.
>  - Rebase to latest linux-media/master

Kieran/Laurent,

What's the status of this patchset?

Regards,
Mauro

> 
> Kieran Bingham (6):
>   media: uvcvideo: Refactor URB descriptors
>   media: uvcvideo: Convert decode functions to use new context structure
>   media: uvcvideo: Protect queue internals with helper
>   media: uvcvideo: queue: Simplify spin-lock usage
>   media: uvcvideo: queue: Support asynchronous buffer handling
>   media: uvcvideo: Move decode processing to process context
> 
>  drivers/media/usb/uvc/uvc_isight.c |   6 +-
>  drivers/media/usb/uvc/uvc_queue.c  | 102 +++++++++++++----
>  drivers/media/usb/uvc/uvc_video.c  | 180 +++++++++++++++++++++---------
>  drivers/media/usb/uvc/uvcvideo.h   |  59 ++++++++--
>  4 files changed, 266 insertions(+), 81 deletions(-)
> 
> base-commit: a77cfdf6bd06eef0dadea2b541a7c01502b1b4f6



Thanks,
Mauro