| Message ID | 20230228110145.3770525-1-claudiu.beznea@microchip.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | ASoC: mchp-pdmc: fix poc noises when starting capture | expand |
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. You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed. If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced. Please add any relevant lists and maintainers to the CCs when replying to this mail. Thanks, Mark
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 For this workaround to work step 6 need to be executed at the end. For step 6 was added patch 1/3 from this series. With this, component DAI driver sets its struct snd_soc_component_driver::start_dma_last = 1 and proper action is taken based on this flag when starting DAI trigger vs DMA. Thank you, Claudiu Beznea Changes in v3: - update the commit message of patch 2/3 to be more descriptive - in patch 3/3 initialize dd->startup_delay_us before calling of_property_read_u32() and don't check its return value; property is optional and the the default value is 150ms Changes in v2: - patch 1/3 from v1 is now "ASoC: soc-pcm: add option to start DMA after DAI" - pass start_dma_last from component DAI driver object (struct snd_soc_component_driver::start_dma_last); adapt patch 3/3 after this; - in patch 1/3 s/Do we need to start dma first/Do we need to start dma last in comment from soc_pcm_trigger() - collect review tag from Krzysztof Claudiu Beznea (3): ASoC: soc-pcm: add option to start DMA after DAI ASoC: dt-bindings: sama7g5-pdmc: add microchip,startup-delay-us binding ASoC: mchp-pdmc: fix poc noise at capture startup Claudiu Beznea (3): ASoC: soc-pcm: add option to start DMA after DAI ASoC: dt-bindings: sama7g5-pdmc: add microchip,startup-delay-us binding ASoC: mchp-pdmc: fix poc noise at capture startup .../sound/microchip,sama7g5-pdmc.yaml | 6 +++ include/sound/soc-component.h | 2 + sound/soc/atmel/mchp-pdmc.c | 53 +++++++++++++++++-- sound/soc/soc-pcm.c | 27 ++++++++-- 4 files changed, 78 insertions(+), 10 deletions(-)