According to the documentation I have, DREQ pacing should be required here.
The DREQ# hasn't changed since the BCM2835. As soon as we attempt to setup
DREQ, DMA stalls and there's no clear reason why as of yet. Setting this
back to NONE seems to work just as well, though it's yet to be determined if
this is a sustainable model in high-throughput scenarios.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
(1) The channel mask is get from "brcm,dma-channel-mask" property of
dma node, and if not provided, from "broadcom,channels" property.
(2) Consequently, sdhci driver does not allocate any specific channel.
(3) Use CS_RESET bit for initial channel reset.
Differential Revision: https://reviews.freebsd.org/D4303
