ASoC: davinci-mcasp: Fix master capture only mode

When McASP is used as TX/RX synchronous (TX side generating clocks for RX
side also) and only capture is used we need to configure the number of TX
slots in order McASP to be able to generate the Frame sync.

Fixes: 9273de1940d9e ("ASoC: davinci-mcasp: Add set_tdm_slots() support")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/davinci/davinci-mcasp.c

@@ -908,6 +908,14 @@ static int mcasp_i2s_hw_param(struct davinci_mcasp *mcasp, int stream,
 		mcasp_set_bits(mcasp, DAVINCI_MCASP_RXFMT_REG, busel | RXORD);
 		mcasp_mod_bits(mcasp, DAVINCI_MCASP_RXFMCTL_REG,
 			       FSRMOD(total_slots), FSRMOD(0x1FF));
+		/*
+		 * If McASP is set to be TX/RX synchronous and the playback is
+		 * not running already we need to configure the TX slots in
+		 * order to have correct FSX on the bus
+		 */
+		if (mcasp_is_synchronous(mcasp) && !mcasp->channels)
+			mcasp_mod_bits(mcasp, DAVINCI_MCASP_TXFMCTL_REG,
+				       FSXMOD(total_slots), FSXMOD(0x1FF));
 	}
 
 	return 0;