i2c: sh_mobile: send STOP according to datasheet

Message ID 20171110115210.21955-1-wsa+renesas@sang-engineering.com
State New
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  • i2c: sh_mobile: send STOP according to datasheet
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Commit Message

Wolfram Sang Nov. 10, 2017, 11:52 a.m.
We initiate STOP (or REP_START) on the second last WAIT interrupt
currently. This works fine but is not according to the datasheet which
says to do it on the last WAIT interrupt. This also simplifies the code
quite a lot, so let's do it.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Jacopo: another one to test, pretty please.

 drivers/i2c/busses/i2c-sh_mobile.c | 29 ++++++-----------------------
 1 file changed, 6 insertions(+), 23 deletions(-)

Comments

Niklas =?iso-8859-1?Q?S=F6derlund?= Nov. 10, 2017, 1:29 p.m. | #1
Hi Wolfram,

On 2017-11-10 12:52:10 +0100, Wolfram Sang wrote:
> We initiate STOP (or REP_START) on the second last WAIT interrupt
> currently. This works fine but is not according to the datasheet which
> says to do it on the last WAIT interrupt. This also simplifies the code
> quite a lot, so let's do it.

I like this change and I checked the flow diagrams in chapter '56.4
Operation' of the Gen2 datasheet rev 2.0 and chapter '58.3 Operation' of 
the Gen3 datasheet rev 0.80, and it makes sens for both.

> 
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

For Gen2 and Gen3:

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
> 
> Jacopo: another one to test, pretty please.
> 
>  drivers/i2c/busses/i2c-sh_mobile.c | 29 ++++++-----------------------
>  1 file changed, 6 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
> index 40a66d466c3c49..c904be631db302 100644
> --- a/drivers/i2c/busses/i2c-sh_mobile.c
> +++ b/drivers/i2c/busses/i2c-sh_mobile.c
> @@ -40,21 +40,21 @@
>  /* BUS:     S     A8     ACK   P(*)                                         */
>  /* IRQ:       DTE   WAIT                                                    */
>  /* ICIC:                                                                    */
> -/* ICCR: 0x94 0x90                                                          */
> +/* ICCR: 0x94       0x90                                                    */
>  /* ICDR:      A8                                                            */
>  /*                                                                          */
>  /* 1 byte transmit                                                          */
>  /* BUS:     S     A8     ACK   D8(1)   ACK   P(*)                           */
>  /* IRQ:       DTE   WAIT         WAIT                                       */
>  /* ICIC:      -DTE                                                          */
> -/* ICCR: 0x94       0x90                                                    */
> +/* ICCR: 0x94                    0x90                                       */
>  /* ICDR:      A8    D8(1)                                                   */
>  /*                                                                          */
>  /* 2 byte transmit                                                          */
>  /* BUS:     S     A8     ACK   D8(1)   ACK   D8(2)   ACK   P(*)             */
>  /* IRQ:       DTE   WAIT         WAIT          WAIT                         */
>  /* ICIC:      -DTE                                                          */
> -/* ICCR: 0x94                    0x90                                       */
> +/* ICCR: 0x94                                  0x90                         */
>  /* ICDR:      A8    D8(1)        D8(2)                                      */
>  /*                                                                          */
>  /* 3 bytes or more, +---------+ gets repeated                               */
> @@ -113,7 +113,6 @@ enum sh_mobile_i2c_op {
>  	OP_TX_FIRST,
>  	OP_TX,
>  	OP_TX_STOP,
> -	OP_TX_STOP_DATA,
>  	OP_TX_TO_RX,
>  	OP_RX,
>  	OP_RX_STOP,
> @@ -319,10 +318,7 @@ static unsigned char i2c_op(struct sh_mobile_i2c_data *pd,
>  	case OP_TX: /* write data */
>  		iic_wr(pd, ICDR, data);
>  		break;
> -	case OP_TX_STOP_DATA: /* write data and issue a stop afterwards */
> -		iic_wr(pd, ICDR, data);
> -		/* fallthrough */
> -	case OP_TX_STOP: /* issue a stop */
> +	case OP_TX_STOP: /* issue a stop (or rep_start) */
>  		iic_wr(pd, ICCR, pd->send_stop ? ICCR_ICE | ICCR_TRS
>  					       : ICCR_ICE | ICCR_TRS | ICCR_BBSY);
>  		break;
> @@ -356,11 +352,6 @@ static bool sh_mobile_i2c_is_first_byte(struct sh_mobile_i2c_data *pd)
>  	return pd->pos == -1;
>  }
>  
> -static bool sh_mobile_i2c_is_last_byte(struct sh_mobile_i2c_data *pd)
> -{
> -	return pd->pos == pd->msg->len - 1;
> -}
> -
>  static void sh_mobile_i2c_get_data(struct sh_mobile_i2c_data *pd,
>  				   unsigned char *buf)
>  {
> @@ -378,20 +369,12 @@ static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
>  	unsigned char data;
>  
>  	if (pd->pos == pd->msg->len) {
> -		/* Send stop if we haven't yet (DMA case) */
> -		if (pd->send_stop && pd->stop_after_dma)
> -			i2c_op(pd, OP_TX_STOP, 0);
> +		i2c_op(pd, OP_TX_STOP, 0);
>  		return 1;
>  	}
>  
>  	sh_mobile_i2c_get_data(pd, &data);
> -
> -	if (sh_mobile_i2c_is_last_byte(pd))
> -		i2c_op(pd, OP_TX_STOP_DATA, data);
> -	else if (sh_mobile_i2c_is_first_byte(pd))
> -		i2c_op(pd, OP_TX_FIRST, data);
> -	else
> -		i2c_op(pd, OP_TX, data);
> +	i2c_op(pd, sh_mobile_i2c_is_first_byte(pd) ? OP_TX_FIRST : OP_TX, data);
>  
>  	pd->pos++;
>  	return 0;
> -- 
> 2.11.0
>
jacopo mondi Nov. 14, 2017, 9:10 a.m. | #2
Hi Wolfram,

On Fri, Nov 10, 2017 at 12:52:10PM +0100, Wolfram Sang wrote:
> We initiate STOP (or REP_START) on the second last WAIT interrupt
> currently. This works fine but is not according to the datasheet which
> says to do it on the last WAIT interrupt. This also simplifies the code
> quite a lot, so let's do it.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>
> Jacopo: another one to test, pretty please.

No regressions on Migo-R during image capture.

Tested-by: Jacopo Mondi <jacopo+renesas@jmondi.org>

Thanks
  j

>
>  drivers/i2c/busses/i2c-sh_mobile.c | 29 ++++++-----------------------
>  1 file changed, 6 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
> index 40a66d466c3c49..c904be631db302 100644
> --- a/drivers/i2c/busses/i2c-sh_mobile.c
> +++ b/drivers/i2c/busses/i2c-sh_mobile.c
> @@ -40,21 +40,21 @@
>  /* BUS:     S     A8     ACK   P(*)                                         */
>  /* IRQ:       DTE   WAIT                                                    */
>  /* ICIC:                                                                    */
> -/* ICCR: 0x94 0x90                                                          */
> +/* ICCR: 0x94       0x90                                                    */
>  /* ICDR:      A8                                                            */
>  /*                                                                          */
>  /* 1 byte transmit                                                          */
>  /* BUS:     S     A8     ACK   D8(1)   ACK   P(*)                           */
>  /* IRQ:       DTE   WAIT         WAIT                                       */
>  /* ICIC:      -DTE                                                          */
> -/* ICCR: 0x94       0x90                                                    */
> +/* ICCR: 0x94                    0x90                                       */
>  /* ICDR:      A8    D8(1)                                                   */
>  /*                                                                          */
>  /* 2 byte transmit                                                          */
>  /* BUS:     S     A8     ACK   D8(1)   ACK   D8(2)   ACK   P(*)             */
>  /* IRQ:       DTE   WAIT         WAIT          WAIT                         */
>  /* ICIC:      -DTE                                                          */
> -/* ICCR: 0x94                    0x90                                       */
> +/* ICCR: 0x94                                  0x90                         */
>  /* ICDR:      A8    D8(1)        D8(2)                                      */
>  /*                                                                          */
>  /* 3 bytes or more, +---------+ gets repeated                               */
> @@ -113,7 +113,6 @@ enum sh_mobile_i2c_op {
>  	OP_TX_FIRST,
>  	OP_TX,
>  	OP_TX_STOP,
> -	OP_TX_STOP_DATA,
>  	OP_TX_TO_RX,
>  	OP_RX,
>  	OP_RX_STOP,
> @@ -319,10 +318,7 @@ static unsigned char i2c_op(struct sh_mobile_i2c_data *pd,
>  	case OP_TX: /* write data */
>  		iic_wr(pd, ICDR, data);
>  		break;
> -	case OP_TX_STOP_DATA: /* write data and issue a stop afterwards */
> -		iic_wr(pd, ICDR, data);
> -		/* fallthrough */
> -	case OP_TX_STOP: /* issue a stop */
> +	case OP_TX_STOP: /* issue a stop (or rep_start) */
>  		iic_wr(pd, ICCR, pd->send_stop ? ICCR_ICE | ICCR_TRS
>  					       : ICCR_ICE | ICCR_TRS | ICCR_BBSY);
>  		break;
> @@ -356,11 +352,6 @@ static bool sh_mobile_i2c_is_first_byte(struct sh_mobile_i2c_data *pd)
>  	return pd->pos == -1;
>  }
>
> -static bool sh_mobile_i2c_is_last_byte(struct sh_mobile_i2c_data *pd)
> -{
> -	return pd->pos == pd->msg->len - 1;
> -}
> -
>  static void sh_mobile_i2c_get_data(struct sh_mobile_i2c_data *pd,
>  				   unsigned char *buf)
>  {
> @@ -378,20 +369,12 @@ static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
>  	unsigned char data;
>
>  	if (pd->pos == pd->msg->len) {
> -		/* Send stop if we haven't yet (DMA case) */
> -		if (pd->send_stop && pd->stop_after_dma)
> -			i2c_op(pd, OP_TX_STOP, 0);
> +		i2c_op(pd, OP_TX_STOP, 0);
>  		return 1;
>  	}
>
>  	sh_mobile_i2c_get_data(pd, &data);
> -
> -	if (sh_mobile_i2c_is_last_byte(pd))
> -		i2c_op(pd, OP_TX_STOP_DATA, data);
> -	else if (sh_mobile_i2c_is_first_byte(pd))
> -		i2c_op(pd, OP_TX_FIRST, data);
> -	else
> -		i2c_op(pd, OP_TX, data);
> +	i2c_op(pd, sh_mobile_i2c_is_first_byte(pd) ? OP_TX_FIRST : OP_TX, data);
>
>  	pd->pos++;
>  	return 0;
> --
> 2.11.0
>

Patch

diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
index 40a66d466c3c49..c904be631db302 100644
--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c
@@ -40,21 +40,21 @@ 
 /* BUS:     S     A8     ACK   P(*)                                         */
 /* IRQ:       DTE   WAIT                                                    */
 /* ICIC:                                                                    */
-/* ICCR: 0x94 0x90                                                          */
+/* ICCR: 0x94       0x90                                                    */
 /* ICDR:      A8                                                            */
 /*                                                                          */
 /* 1 byte transmit                                                          */
 /* BUS:     S     A8     ACK   D8(1)   ACK   P(*)                           */
 /* IRQ:       DTE   WAIT         WAIT                                       */
 /* ICIC:      -DTE                                                          */
-/* ICCR: 0x94       0x90                                                    */
+/* ICCR: 0x94                    0x90                                       */
 /* ICDR:      A8    D8(1)                                                   */
 /*                                                                          */
 /* 2 byte transmit                                                          */
 /* BUS:     S     A8     ACK   D8(1)   ACK   D8(2)   ACK   P(*)             */
 /* IRQ:       DTE   WAIT         WAIT          WAIT                         */
 /* ICIC:      -DTE                                                          */
-/* ICCR: 0x94                    0x90                                       */
+/* ICCR: 0x94                                  0x90                         */
 /* ICDR:      A8    D8(1)        D8(2)                                      */
 /*                                                                          */
 /* 3 bytes or more, +---------+ gets repeated                               */
@@ -113,7 +113,6 @@  enum sh_mobile_i2c_op {
 	OP_TX_FIRST,
 	OP_TX,
 	OP_TX_STOP,
-	OP_TX_STOP_DATA,
 	OP_TX_TO_RX,
 	OP_RX,
 	OP_RX_STOP,
@@ -319,10 +318,7 @@  static unsigned char i2c_op(struct sh_mobile_i2c_data *pd,
 	case OP_TX: /* write data */
 		iic_wr(pd, ICDR, data);
 		break;
-	case OP_TX_STOP_DATA: /* write data and issue a stop afterwards */
-		iic_wr(pd, ICDR, data);
-		/* fallthrough */
-	case OP_TX_STOP: /* issue a stop */
+	case OP_TX_STOP: /* issue a stop (or rep_start) */
 		iic_wr(pd, ICCR, pd->send_stop ? ICCR_ICE | ICCR_TRS
 					       : ICCR_ICE | ICCR_TRS | ICCR_BBSY);
 		break;
@@ -356,11 +352,6 @@  static bool sh_mobile_i2c_is_first_byte(struct sh_mobile_i2c_data *pd)
 	return pd->pos == -1;
 }
 
-static bool sh_mobile_i2c_is_last_byte(struct sh_mobile_i2c_data *pd)
-{
-	return pd->pos == pd->msg->len - 1;
-}
-
 static void sh_mobile_i2c_get_data(struct sh_mobile_i2c_data *pd,
 				   unsigned char *buf)
 {
@@ -378,20 +369,12 @@  static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
 	unsigned char data;
 
 	if (pd->pos == pd->msg->len) {
-		/* Send stop if we haven't yet (DMA case) */
-		if (pd->send_stop && pd->stop_after_dma)
-			i2c_op(pd, OP_TX_STOP, 0);
+		i2c_op(pd, OP_TX_STOP, 0);
 		return 1;
 	}
 
 	sh_mobile_i2c_get_data(pd, &data);
-
-	if (sh_mobile_i2c_is_last_byte(pd))
-		i2c_op(pd, OP_TX_STOP_DATA, data);
-	else if (sh_mobile_i2c_is_first_byte(pd))
-		i2c_op(pd, OP_TX_FIRST, data);
-	else
-		i2c_op(pd, OP_TX, data);
+	i2c_op(pd, sh_mobile_i2c_is_first_byte(pd) ? OP_TX_FIRST : OP_TX, data);
 
 	pd->pos++;
 	return 0;