ASoC: dmaengine: support deferred probe for DMA channels

Enhance dmaengine_pcm_request_chan_of() to support deferred probe for
DMA channels, by using the new dma_request_slave_channel_or_err() API.
This prevents snd_dmaengine_pcm_register() from succeeding without
acquiring DMA channels due to the relevant DMA controller not yet being
registered.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 16 insertions, 4 deletions

diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
index 5b70c556fba3..585eaa69e8c3 100644
--- a/sound/soc/soc-generic-dmaengine-pcm.c
+++ b/sound/soc/soc-generic-dmaengine-pcm.c
@@ -287,16 +287,17 @@ static const char * const dmaengine_pcm_dma_channel_names[] = {
         [SNDRV_PCM_STREAM_CAPTURE] = "rx",
 };
 
-static void dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
+static int dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
         struct device *dev, const struct snd_dmaengine_pcm_config *config)
 {
         unsigned int i;
         const char *name;
+        struct dma_chan *chan;
 
         if ((pcm->flags & (SND_DMAENGINE_PCM_FLAG_NO_DT |
                            SND_DMAENGINE_PCM_FLAG_CUSTOM_CHANNEL_NAME)) ||
             !dev->of_node)
-                return;
+                return 0;
 
         if (config->dma_dev) {
                 /*
@@ -318,13 +319,22 @@ static void dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
                         name = dmaengine_pcm_dma_channel_names[i];
                 if (config->chan_names[i])
                         name = config->chan_names[i];
-                pcm->chan[i] = dma_request_slave_channel(dev, name);
+                chan = dma_request_slave_channel_reason(dev, name);
+                if (IS_ERR(chan)) {
+                        if (PTR_ERR(pcm->chan[i]) == -EPROBE_DEFER)
+                                return -EPROBE_DEFER;
+                        pcm->chan[i] = NULL;
+                } else {
+                        pcm->chan[i] = chan;
+                }
                 if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
                         break;
         }
 
         if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
                 pcm->chan[1] = pcm->chan[0];
+
+        return 0;
 }
 
 static void dmaengine_pcm_release_chan(struct dmaengine_pcm *pcm)
@@ -360,7 +370,9 @@ int snd_dmaengine_pcm_register(struct device *dev,
         pcm->config = config;
         pcm->flags = flags;
 
-        dmaengine_pcm_request_chan_of(pcm, dev, config);
+        ret = dmaengine_pcm_request_chan_of(pcm, dev, config);
+        if (ret)
+                goto err_free_dma;
 
         if (flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE)
                 ret = snd_soc_add_platform(dev, &pcm->platform,