ASoC: mcasp: don't override bclk divider if it was provided by the machine

If a machine driver provides an BCLK divider to the McASP driver, skip the
automatic calculation.

This fixes machines on which the physical sample transport always works
in 32 bits, even though not all of them are actually used.
snd_soc_params_to_bclk() will fail to address such cases properly.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/davinci/davinci-mcasp.c

@@ -65,6 +65,7 @@ struct davinci_mcasp {
 	u8	num_serializer;
 	u8	*serial_dir;
 	u8	version;
+	u8	bclk_div;
 	u16	bclk_lrclk_ratio;
 	int	streams;
 
@@ -419,6 +420,7 @@ static int davinci_mcasp_set_clkdiv(struct snd_soc_dai *dai, int div_id, int div
 			       ACLKXDIV(div - 1), ACLKXDIV_MASK);
 		mcasp_mod_bits(mcasp, DAVINCI_MCASP_ACLKRCTL_REG,
 			       ACLKRDIV(div - 1), ACLKRDIV_MASK);
+		mcasp->bclk_div = div;
 		break;
 
 	case 2:		/* BCLK/LRCLK ratio */
@@ -721,8 +723,11 @@ static int davinci_mcasp_hw_params(struct snd_pcm_substream *substream,
 	int period_size = params_period_size(params);
 	int ret;
 
-	/* If mcasp is BCLK master we need to set BCLK divider */
-	if (mcasp->bclk_master && mcasp->sysclk_freq) {
+	/*
+	 * If mcasp is BCLK master, and a BCLK divider was not provided by
+	 * the machine driver, we need to calculate the ratio.
+	 */
+	if (mcasp->bclk_master && mcasp->bclk_div == 0 && mcasp->sysclk_freq) {
 		unsigned int bclk_freq = snd_soc_params_to_bclk(params);
 		unsigned int div = mcasp->sysclk_freq / bclk_freq;
 		if (mcasp->sysclk_freq % bclk_freq != 0) {