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Commit 36bcecd0 authored by Peter Ujfalusi's avatar Peter Ujfalusi Committed by Mark Brown
Browse files

ASoC: davinci-mcasp: Correct TX start sequence 



Follow the sequence described in the TRMs when starting TX. This sequence
will make sure that we are not facing with initial channel swap caused by
no data available in McASP for transmit.

Signed-off-by: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent f114040e

sound/soc/davinci/davinci-mcasp.c

+9 −16
Original line number Diff line number Diff line
@@ -183,31 +183,24 @@ static void mcasp_start_rx(struct davinci_mcasp *mcasp) 


static void mcasp_start_tx(struct davinci_mcasp *mcasp)

{

	u8 offset = 0, i;

	u32 cnt;



	/* Start clocks */

	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXHCLKRST);

	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXCLKRST);

	/* Activate serializer(s) */

	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXSERCLR);

	mcasp_set_reg(mcasp, DAVINCI_MCASP_TXBUF_REG, 0);



	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXSMRST);

	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXFSRST);

	mcasp_set_reg(mcasp, DAVINCI_MCASP_TXBUF_REG, 0);

	for (i = 0; i < mcasp->num_serializer; i++) {

		if (mcasp->serial_dir[i] == TX_MODE) {

			offset = i;

			break;

		}

	}



	/* wait for TX ready */

	/* wait for XDATA to be cleared */

	cnt = 0;

	while (!(mcasp_get_reg(mcasp, DAVINCI_MCASP_XRSRCTL_REG(offset)) &

		 TXSTATE) && (cnt < 100000))

	while (!(mcasp_get_reg(mcasp, DAVINCI_MCASP_TXSTAT_REG) &

		 ~XRDATA) && (cnt < 100000))

		cnt++;



	mcasp_set_reg(mcasp, DAVINCI_MCASP_TXBUF_REG, 0);

	/* Release TX state machine */

	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXSMRST);

	/* Release Frame Sync generator */

	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXFSRST);

}



static void davinci_mcasp_start(struct davinci_mcasp *mcasp, int stream)

sound/soc/davinci/davinci-mcasp.h

+6 −0
Original line number Diff line number Diff line
@@ -252,6 +252,12 @@ 
#define TXSMRST		BIT(11)	/* Transmitter State Machine Reset */

#define TXFSRST		BIT(12)	/* Frame Sync Generator Reset */



/*

 * DAVINCI_MCASP_TXSTAT_REG - Transmitter Status Register Bits

 * DAVINCI_MCASP_RXSTAT_REG - Receiver Status Register Bits

 */

#define XRDATA		BIT(5) /* Transmit/Receive data ready */



/*

 * DAVINCI_MCASP_AMUTE_REG -  Mute Control Register Bits

 */