From 86f29c7442ac4ba5fe19fc2ada457f76c0080dd6 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Thu, 8 Oct 2020 17:11:05 +0100 Subject: 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 Signed-off-by: Mark Brown Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20201008161105.21804-1-broonie@kernel.org Signed-off-by: Mark Brown --- sound/soc/soc-generic-dmaengine-pcm.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'sound') diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c index fb95c1464e66..9ef80a48707e 100644 --- a/sound/soc/soc-generic-dmaengine-pcm.c +++ b/sound/soc/soc-generic-dmaengine-pcm.c @@ -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; -- cgit