[PATCH 1/4] ASoC: davinci-mcasp: Clear TXSTAT register before activating serializers

From: Peter Ujfalusi
Date: Fri Nov 16 2018 - 08:40:40 EST


Follow the guideline from the TRM:
Before starting, clear the respective transmitter and receiver status
registers

To avoid stale state stored in the status registers.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
---
sound/soc/davinci/davinci-mcasp.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index 267aee776b2d..740030b4d37a 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -192,6 +192,7 @@ static void mcasp_start_rx(struct davinci_mcasp *mcasp)
}

/* Activate serializer(s) */
+ mcasp_set_reg(mcasp, DAVINCI_MCASP_RXSTAT_REG, 0xFFFFFFFF);
mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXSERCLR);
/* Release RX state machine */
mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLR_REG, RXSMRST);
@@ -220,6 +221,7 @@ static void mcasp_start_tx(struct davinci_mcasp *mcasp)
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_reg(mcasp, DAVINCI_MCASP_TXSTAT_REG, 0xFFFFFFFF);
mcasp_set_ctl_reg(mcasp, DAVINCI_MCASP_GBLCTLX_REG, TXSERCLR);

/* wait for XDATA to be cleared */
--
Peter

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