Unverified Commit 86f29c74 authored Oct 08, 2020 by Mark Brown

ASoC: dmaengine: Document support for TX only or RX only streams



We intentionally do not return an error if we get a permanent failure
from dma_request_chan() in order to support systems which have TX only
or RX only channels. Add a comment documenting this.

Reported-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Link: https://lore.kernel.org/r/20201008161105.21804-1-broonie@kernel.org


Signed-off-by: Mark Brown <broonie@kernel.org>

parent b899e4fd

sound/soc/soc-generic-dmaengine-pcm.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -386,6 +386,11 @@ static int dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
		name = config->chan_names[i];
		chan = dma_request_chan(dev, name);
		if (IS_ERR(chan)) {
		/*
		* Only report probe deferral errors, channels
		* might not be present for devices that
		* support only TX or only RX.
		*/
		if (PTR_ERR(chan) == -EPROBE_DEFER)
		return -EPROBE_DEFER;
		pcm->chan[i] = NULL;

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