e81e7f9a0e
This patch adds support for scatter gather transfers. If the underlying gadgets sg_supported == true, then the videeobuf2-dma-sg is used and the encode routine maps all scatter entries to separate scatterlists for the usb gadget. When streaming 1080p with request size of 1024 times 3 bytes top shows a difference of about 6.4% CPU load applying this patch: PID USER PR NI VIRT RES %CPU %MEM TIME+ S COMMAND 64 root 0 -20 0.0m 0.0m 7.7 0.0 0:01.25 I [kworker/u5:0-uvcvideo] 83 root 0 -20 0.0m 0.0m 4.5 0.0 0:03.71 I [kworker/u5:3-uvcvideo] 307 root -51 0 0.0m 0.0m 3.8 0.0 0:01.05 S [irq/51-dwc3] vs. 64 root 0 -20 0.0m 0.0m 5.8 0.0 0:01.79 I [kworker/u5:0-uvcvideo] 306 root -51 0 0.0m 0.0m 3.2 0.0 0:01.97 S [irq/51-dwc3] 82 root 0 -20 0.0m 0.0m 0.6 0.0 0:01.86 I [kworker/u5:1-uvcvideo] Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de> Link: https://lore.kernel.org/r/20210628155311.16762-5-m.grzeschik@pengutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.