On Tue, 28 Feb 2023 13:01:42 +0200, Claudiu Beznea wrote:
To start capture on Microchip PDMC the enable bits for each supported microphone need to be set. After this bit is set the PDMC starts to receive data from microphones and it considers this data as valid data. Thus if microphones are not ready the PDMC captures anyway data from its lines. This data is interpreted by the human ear as poc noises.
To avoid this the following software workaround need to be applied when starting capture: 1/ enable PDMC channel 2/ wait 150ms 3/ execute 16 dummy reads from RHR 4/ clear interrupts 5/ enable interrupts 6/ enable DMA channel
[...]
Applied to
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next
Thanks!
[1/3] ASoC: soc-pcm: add option to start DMA after DAI commit: 54fc4b72b630e1cb92a21140084c6852babbb234 [2/3] ASoC: dt-bindings: sama7g5-pdmc: add microchip,startup-delay-us binding commit: 143a2f011c4471511887807822d3fd71f25f5169 [3/3] ASoC: mchp-pdmc: fix poc noise at capture startup commit: c5682e2ba1327d08987a7cabc7b5b40bf3bc131f
All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.
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Thanks, Mark