c5682e2ba1
Microchip PDMC IP doesn't filter microphone noises on startup. By default,
it captures data received from digital microphones after
the MCHP_PDMC_MR.EN bits are set. Thus when enable is set on PDMC side the
digital microphones might not be ready yet and PDMC captures data from then
in this time. This data captured is poc noise. To avoid this the software
workaround is to the following:
1/ enable PDMC channel
2/ wait 150ms (on SAMA7G5-EK setup)
3/ execute 16 dummy reads from RHR
4/ clear interrupts
5/ enable interrupts
6/ enable DMA channel
Fixes: 50291652af52 ("ASoC: atmel: mchp-pdmc: add PDMC driver")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20230228110145.3770525-4-claudiu.beznea@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.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.