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: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index 0eed9b1b24e1a5410eb4ddcc90908e919f559f65..e1c1f40dd77f26a9271899bca2f20fb9d6a85e68 100644 (file)
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -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)

diff --git a/sound/soc/davinci/davinci-mcasp.h b/sound/soc/davinci/davinci-mcasp.h
index 98fbc451892a5e94d851d53001ac89551ed1e3e8..9737108f030527821fd76a1921566c309a3d4fa3 100644 (file)
--- a/sound/soc/davinci/davinci-mcasp.h
+++ b/sound/soc/davinci/davinci-mcasp.h
@@ -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
  */