ASoC: stm32: sai: add restriction on mmap support

Do not support mmap in S/PDIF mode. In S/PDIF mode
the buffer has to be copied, to allow the channel status
bits insertion.

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Link: https://lore.kernel.org/r/20191104133654.28750-1-olivier.moysan@st.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/stm/stm32_sai_sub.c

@@ -1218,6 +1218,16 @@ static int stm32_sai_pcm_process_spdif(struct snd_pcm_substream *substream,
 	return 0;
 }
 
+/* No support of mmap in S/PDIF mode */
+static const struct snd_pcm_hardware stm32_sai_pcm_hw_spdif = {
+	.info = SNDRV_PCM_INFO_INTERLEAVED,
+	.buffer_bytes_max = 8 * PAGE_SIZE,
+	.period_bytes_min = 1024,
+	.period_bytes_max = PAGE_SIZE,
+	.periods_min = 2,
+	.periods_max = 8,
+};
+
 static const struct snd_pcm_hardware stm32_sai_pcm_hw = {
 	.info = SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP,
 	.buffer_bytes_max = 8 * PAGE_SIZE,
@@ -1270,7 +1280,7 @@ static const struct snd_dmaengine_pcm_config stm32_sai_pcm_config = {
 };
 
 static const struct snd_dmaengine_pcm_config stm32_sai_pcm_config_spdif = {
-	.pcm_hardware = &stm32_sai_pcm_hw,
+	.pcm_hardware = &stm32_sai_pcm_hw_spdif,
 	.prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config,
 	.process = stm32_sai_pcm_process_spdif,
 };