ASoC: don't touch pxa-ssp registers when stream is running

In pxa_ssp_set_dai_fmt(), check whether there is anything to do at all.
If there would be but the SSP port is in use already, bail out.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/sound/soc/pxa/pxa-ssp.c b/sound/soc/pxa/pxa-ssp.c
index 7fc13f03d1d2..52d97c4b82b1 100644
--- a/sound/soc/pxa/pxa-ssp.c
+++ b/sound/soc/pxa/pxa-ssp.c
@@ -522,6 +522,17 @@ static int pxa_ssp_set_dai_fmt(struct snd_soc_dai *cpu_dai,
         u32 sscr1;
         u32 sspsp;
 
+        /* check if we need to change anything at all */
+        if (priv->dai_fmt == fmt)
+                return 0;
+
+        /* we can only change the settings if the port is not in use */
+        if (ssp_read_reg(ssp, SSCR0) & SSCR0_SSE) {
+                dev_err(&ssp->pdev->dev,
+                        "can't change hardware dai format: stream is in use");
+                return -EINVAL;
+        }
+
         /* reset port settings */
         sscr0 = ssp_read_reg(ssp, SSCR0) &
                 (SSCR0_ECS |  SSCR0_NCS | SSCR0_MOD | SSCR0_ACS);