[ALSA] s3c24xx-pcm: fix hw_params dma handling

Since the PCM emulation can call multiple times to hw_setup(), but we
can only once allocate/request the DMA channel, we have to handle
this gracefully.

Signed-off-by: Harald Welte <laforge@openmoko.org>
Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

diff --git a/sound/soc/s3c24xx/s3c24xx-pcm.c b/sound/soc/s3c24xx/s3c24xx-pcm.c
index bfbdc3cbd43b5e936c0614c9429d1414e4a4bb56..4107a87d4de3cb39fdcf7f8d51432e5a37361c93 100644 (file)
--- a/sound/soc/s3c24xx/s3c24xx-pcm.c
+++ b/sound/soc/s3c24xx/s3c24xx-pcm.c
@@ -158,18 +158,22 @@ static int s3c24xx_pcm_hw_params(struct snd_pcm_substream *substream,
        if (!dma)
                return 0;
 
-       /* prepare DMA */
-       prtd->params = dma;
+       /* this may get called several times by oss emulation
+        * with different params -HW */
+       if (prtd->params == NULL) {
+               /* prepare DMA */
+               prtd->params = dma;
 
-       DBG("params %p, client %p, channel %d\n", prtd->params,
-               prtd->params->client, prtd->params->channel);
+               DBG("params %p, client %p, channel %d\n", prtd->params,
+                       prtd->params->client, prtd->params->channel);
 
-       ret = s3c2410_dma_request(prtd->params->channel,
-                                 prtd->params->client, NULL);
+               ret = s3c2410_dma_request(prtd->params->channel,
+                                         prtd->params->client, NULL);
 
-       if (ret) {
-               DBG(KERN_ERR "failed to get dma channel\n");
-               return ret;
+               if (ret) {
+                       DBG(KERN_ERR "failed to get dma channel\n");
+                       return ret;
+               }
        }
 
        /* channel needs configuring for mem=>device, increment memory addr,