[alsa-devel] [PATCH v2 2/4] ASoC: davinci-mcasp: Correct RX start sequence

[Peter Ujfalusi]

Follow the sequence described in the TRMs when starting RX.
Write to RXBUF register was not correct and there is no need to release the
RX state machine/Receive frame sync generator twice.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
---
 sound/soc/davinci/davinci-mcasp.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index c6f2a7b9b6f6..0250353dc6ab 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -136,9 +136,9 @@ static bool mcasp_is_synchronous(struct davinci_mcasp *mcasp)
 
 static void mcasp_start_rx(struct davinci_mcasp *mcasp)
 {
+	/* Start clocks */
 	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXHCLKRST);
 	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXCLKRST);
-
 	/*
 	 * When ASYNC == 0 the transmit and receive sections operate
 	 * synchronously from the transmit clock and frame sync. We need to make
@@ -149,16 +149,12 @@ static void mcasp_start_rx(struct davinci_mcasp *mcasp)
 		mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXCLKRST);
 	}
 
+	/* Activate serializer(s) */
 	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXSERCLR);
-	mcasp_set_reg(mcasp, DAVINCI_MCASP_RXBUF_REG, 0);
-
-	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXSMRST);
-	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXFSRST);
-	mcasp_set_reg(mcasp, DAVINCI_MCASP_RXBUF_REG, 0);
-
+	/* Release RX state machine */
 	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXSMRST);
+	/* Release Frame Sync generator */
 	mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXFSRST);
-
 	if (mcasp_is_synchronous(mcasp))
 		mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXFSRST);
 }
-- 
1.9.1