ASoC: fsl: Disable SSI in trigger() if RE/TE are both cleared

The code enabled SSIEN when triggered by SNDRV_PCM_TRIGGER_START,
so move the disable code to SNDRV_PCM_TRIGGER_STOP for symmetric.

This also allows us to use the SSI driver more flexible so that
it can support some use cases like "aplay S16_LE.wav S24_LE.wav"
which would call the driver in sequence like:
 startup()->hw_params(S16_LE)->trigger(START)->tirgger(STOP)->
 hw_params(S24_LE)->trigger(START)->tirgger(STOP)->shutdown()

If we disable SSIEN in shutdown(), the second hw_params() would
bypass the sample bits setting while using symmetric_rate.
Signed-off-by: Nicolin Chen <b42378@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/fsl/fsl_ssi.c

@@ -510,6 +510,9 @@ static int fsl_ssi_trigger(struct snd_pcm_substream *substream, int cmd,
 			write_ssi_mask(&ssi->scr, CCSR_SSI_SCR_TE, 0);
 		else
 			write_ssi_mask(&ssi->scr, CCSR_SSI_SCR_RE, 0);
+
+		if ((read_ssi(&ssi->scr) & (CCSR_SSI_SCR_TE | CCSR_SSI_SCR_RE)) == 0)
+			write_ssi_mask(&ssi->scr, CCSR_SSI_SCR_SSIEN, 0);
 		break;
 
 	default:
@@ -534,15 +537,6 @@ static void fsl_ssi_shutdown(struct snd_pcm_substream *substream,
 		ssi_private->first_stream = ssi_private->second_stream;
 
 	ssi_private->second_stream = NULL;
-
-	/*
-	 * If this is the last active substream, disable the SSI.
-	 */
-	if (!ssi_private->first_stream) {
-		struct ccsr_ssi __iomem *ssi = ssi_private->ssi;
-
-		write_ssi_mask(&ssi->scr, CCSR_SSI_SCR_SSIEN, 0);
-	}
 }
 
 static int fsl_ssi_dai_probe(struct snd_soc_dai *dai)