[PATCH 2/2] pxa-ssp: don't touch registers if stream is running

[Daniel Mack]

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 at caiaq.de>
Cc: Philipp Zabel <philipp.zabel at gmail.com>
Cc: Liam Girdwood <lrg at kernel.org>
---
 sound/soc/pxa/pxa-ssp.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/sound/soc/pxa/pxa-ssp.c b/sound/soc/pxa/pxa-ssp.c
index 1b3a81c..569c0a6 100644
--- a/sound/soc/pxa/pxa-ssp.c
+++ b/sound/soc/pxa/pxa-ssp.c
@@ -525,6 +525,17 @@ 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);
-- 
1.6.2