[PATCH 0/2] ASoC: davinci-mcasp: Correct start sequences for TX/RX

[PATCH 0/2] ASoC: davinci-mcasp: Correct start sequences for TX/RX

[Peter Ujfalusi]

Hi,

The startup sequence for TX and RX was not correct, not following the
programming sequence from the TRM.
This could cause initial channel swap when starting TX.

The change has been tested on AM335x and AM437x but it should be valid for all
devices.

Regards,
Peter
---
Peter Ujfalusi (2):
  ASoC: davinci-mcasp: Correct TX start sequence
  ASoC: davinci-mcasp: Correct RX start sequence

 sound/soc/davinci/davinci-mcasp.c | 37 +++++++++++++------------------------
 sound/soc/davinci/davinci-mcasp.h |  6 ++++++
 2 files changed, 19 insertions(+), 24 deletions(-)

-- 
1.9.1

[PATCH 1/2] ASoC: davinci-mcasp: Correct TX start sequence

[Peter Ujfalusi]

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>
---
 sound/soc/davinci/davinci-mcasp.c | 25 +++++++++----------------
 sound/soc/davinci/davinci-mcasp.h |  6 ++++++
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index a01ae97c90aa..c6f2a7b9b6f6 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -165,31 +165,24 @@ 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 8fed757d6087..53243c22818d 100644
--- a/sound/soc/davinci/davinci-mcasp.h
+++ b/sound/soc/davinci/davinci-mcasp.h
@@ -253,6 +253,12 @@
 #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
  */
 #define MUTENA(val)	(val)
-- 
1.9.1

[PATCH 2/2] 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@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

Re: [PATCH 0/2] ASoC: davinci-mcasp: Correct start sequences for TX/RX

[Peter Ujfalusi]

On 03/28/2014 09:18 AM, Peter Ujfalusi wrote:
> Hi,
> 
> The startup sequence for TX and RX was not correct, not following the
> programming sequence from the TRM.
> This could cause initial channel swap when starting TX.
> 
> The change has been tested on AM335x and AM437x but it should be valid for all
> devices.

I have found issue with the way the streams are stopped also. I will resend
the series with that later on today.

> 
> Regards,
> Peter
> ---
> Peter Ujfalusi (2):
>   ASoC: davinci-mcasp: Correct TX start sequence
>   ASoC: davinci-mcasp: Correct RX start sequence
> 
>  sound/soc/davinci/davinci-mcasp.c | 37 +++++++++++++------------------------
>  sound/soc/davinci/davinci-mcasp.h |  6 ++++++
>  2 files changed, 19 insertions(+), 24 deletions(-)
> 


-- 
Péter