ASoC: check for substream not channels_min in pcm engines

This is a follow up on 53dea36c70c1857 which fixes the other affected
pcm engines.

Description from 53dea36c70c1857:
 Don't rely on the codec's channels_min information to decide wheter or
 not allocate a substream's DMA buffer. Rather check if the substream
 itself was allocated previously.

Without this patch I was seeing null-pointer dereferenc in atmel-pcm.

Signed-off-by: Joachim Eastwood <joachim.eastwood@jotron.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/sound/soc/mid-x86/sst_platform.c b/sound/soc/mid-x86/sst_platform.c
index c2bf172a196e..d34563b12c3b 100644
--- a/sound/soc/mid-x86/sst_platform.c
+++ b/sound/soc/mid-x86/sst_platform.c
@@ -446,13 +446,12 @@ static void sst_pcm_free(struct snd_pcm *pcm)
 
 static int sst_pcm_new(struct snd_soc_pcm_runtime *rtd)
 {
-        struct snd_soc_dai *dai = rtd->cpu_dai;
         struct snd_pcm *pcm = rtd->pcm;
         int retval = 0;
 
         pr_debug("sst_pcm_new called\n");
-        if (dai->driver->playback.channels_min ||
-                        dai->driver->capture.channels_min) {
+        if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream ||
+                        pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream) {
                 retval =  snd_pcm_lib_preallocate_pages_for_all(pcm,
                         SNDRV_DMA_TYPE_CONTINUOUS,
                         snd_dma_continuous_data(GFP_KERNEL),