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Unverified Commit 86f29c74 authored by Mark Brown's avatar Mark Brown
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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: default avatarAndy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@intel.com>
Link: https://lore.kernel.org/r/20201008161105.21804-1-broonie@kernel.org


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent b899e4fd
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......@@ -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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