[PATCH v2 1/4] i2c: imx: Fix reinit_completion() use

[PATCH v2 1/4] i2c: imx: Fix reinit_completion() use

[Esben Haabendal]

From: Esben Haabendal <eha@deif.com>

Make sure to call reinit_completion() before dma is started to avoid race
condition where reinit_completion() is called after complete() and before
wait_for_completion_timeout().

Signed-off-by: Esben Haabendal <eha@deif.com>
Fixes: ce1a78840ff7 ("i2c: imx: add DMA support for freescale i2c driver")
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/i2c/busses/i2c-imx.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 0207e194f84b..39cfd98c7b23 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -368,6 +368,7 @@ static int i2c_imx_dma_xfer(struct imx_i2c_struct *i2c_imx,
 		goto err_desc;
 	}
 
+	reinit_completion(&dma->cmd_complete);
 	txdesc->callback = i2c_imx_dma_callback;
 	txdesc->callback_param = i2c_imx;
 	if (dma_submit_error(dmaengine_submit(txdesc))) {
@@ -622,7 +623,6 @@ static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
 	 * The first byte must be transmitted by the CPU.
 	 */
 	imx_i2c_write_reg(i2c_8bit_addr_from_msg(msgs), i2c_imx, IMX_I2C_I2DR);
-	reinit_completion(&i2c_imx->dma->cmd_complete);
 	time_left = wait_for_completion_timeout(
 				&i2c_imx->dma->cmd_complete,
 				msecs_to_jiffies(DMA_TIMEOUT));
@@ -681,7 +681,6 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
 	if (result)
 		return result;
 
-	reinit_completion(&i2c_imx->dma->cmd_complete);
 	time_left = wait_for_completion_timeout(
 				&i2c_imx->dma->cmd_complete,
 				msecs_to_jiffies(DMA_TIMEOUT));
-- 
2.18.0

[PATCH v2 2/4] i2c: imx: Fix race condition in dma read

[Esben Haabendal]

From: Esben Haabendal <eha@deif.com>

This fixes a race condition, where the DMAEN bit ends up being set after
I2C slave has transmitted a byte following the dummy read.  When that
happens, an interrupt is generated instead, and no DMA request is generated
to kickstart the DMA read, and a timeout happens after DMA_TIMEOUT (1 sec).

Fixed by setting the DMAEN bit before the dummy read.

Signed-off-by: Esben Haabendal <eha@deif.com>
---
 drivers/i2c/busses/i2c-imx.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 39cfd98c7b23..d86f152176a4 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -668,9 +668,6 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
 	struct imx_i2c_dma *dma = i2c_imx->dma;
 	struct device *dev = &i2c_imx->adapter.dev;
 
-	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
-	temp |= I2CR_DMAEN;
-	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
 
 	dma->chan_using = dma->chan_rx;
 	dma->dma_transfer_dir = DMA_DEV_TO_MEM;
@@ -810,6 +807,11 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
 	if ((msgs->len - 1) || block_data)
 		temp &= ~I2CR_TXAK;
 	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+	if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data) {
+		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+		temp |= I2CR_DMAEN;
+		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+	}
 	imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);
-- 
2.18.0

[PATCH v2 3/4] i2c: imx: Simplify stopped state tracking

[Esben Haabendal]

From: Esben Haabendal <eha@deif.com>

Always update the stopped state when busy status have been checked.
This is identical to what was done before, with the exception of error
handling.
Without this change, some errors cause the stopped state to be left in
incorrect state in i2c_imx_stop(), i2c_imx_dma_read(), i2c_imx_read() and
i2c_imx_xfer().

Signed-off-by: Esben Haabendal <eha@deif.com>
---
 drivers/i2c/busses/i2c-imx.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index d86f152176a4..1db8e6790afc 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -421,10 +421,14 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
 			return -EAGAIN;
 		}
 
-		if (for_busy && (temp & I2SR_IBB))
+		if (for_busy && (temp & I2SR_IBB)) {
+			i2c_imx->stopped = 0;
 			break;
-		if (!for_busy && !(temp & I2SR_IBB))
+		}
+		if (!for_busy && !(temp & I2SR_IBB)) {
+			i2c_imx->stopped = 1;
 			break;
+		}
 		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
 			dev_dbg(&i2c_imx->adapter.dev,
 				"<%s> I2C bus is busy\n", __func__);
@@ -538,7 +542,6 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
 	result = i2c_imx_bus_busy(i2c_imx, 1);
 	if (result)
 		return result;
-	i2c_imx->stopped = 0;
 
 	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
 	temp &= ~I2CR_DMAEN;
@@ -569,7 +572,6 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
 
 	if (!i2c_imx->stopped) {
 		i2c_imx_bus_busy(i2c_imx, 0);
-		i2c_imx->stopped = 1;
 	}
 
 	/* Disable I2C controller */
@@ -724,7 +726,6 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
 		temp &= ~(I2CR_MSTA | I2CR_MTX);
 		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
 		i2c_imx_bus_busy(i2c_imx, 0);
-		i2c_imx->stopped = 1;
 	} else {
 		/*
 		 * For i2c master receiver repeat restart operation like:
@@ -852,7 +853,6 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
 				temp &= ~(I2CR_MSTA | I2CR_MTX);
 				imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
 				i2c_imx_bus_busy(i2c_imx, 0);
-				i2c_imx->stopped = 1;
 			} else {
 				/*
 				 * For i2c master receiver repeat restart operation like:
-- 
2.18.0

[PATCH v2 4/4] arm: dts: ls1021a: Enable I2C DMA support

[Esben Haabendal]

From: Esben Haabendal <eha@deif.com>

Gives substantial performance improvement for transfers larger than 16
bytes (DMA_THRESHOLD).  Smaller transfers are unaffected.

Signed-off-by: Esben Haabendal <eha@deif.com>
---
 arch/arm/boot/dts/ls1021a.dtsi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/ls1021a.dtsi b/arch/arm/boot/dts/ls1021a.dtsi
index c55d479971cc..1e5640701c65 100644
--- a/arch/arm/boot/dts/ls1021a.dtsi
+++ b/arch/arm/boot/dts/ls1021a.dtsi
@@ -363,6 +363,8 @@
 			interrupts = <GIC_SPI 88 IRQ_TYPE_LEVEL_HIGH>;
 			clock-names = "i2c";
 			clocks = <&clockgen 4 1>;
+			dma-names = "tx", "rx";
+			dmas = <&edma0 1 39>, <&edma0 1 38>;
 			status = "disabled";
 		};
 
@@ -374,6 +376,8 @@
 			interrupts = <GIC_SPI 89 IRQ_TYPE_LEVEL_HIGH>;
 			clock-names = "i2c";
 			clocks = <&clockgen 4 1>;
+			dma-names = "tx", "rx";
+			dmas = <&edma0 1 37>, <&edma0 1 36>;
 			status = "disabled";
 		};
 
@@ -385,6 +389,8 @@
 			interrupts = <GIC_SPI 90 IRQ_TYPE_LEVEL_HIGH>;
 			clock-names = "i2c";
 			clocks = <&clockgen 4 1>;
+			dma-names = "tx", "rx";
+			dmas = <&edma0 1 35>, <&edma0 1 34>;
 			status = "disabled";
 		};
 
-- 
2.18.0

Re: [PATCH v2 1/4] i2c: imx: Fix reinit_completion() use

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 607 bytes --]

On Mon, Jul 09, 2018 at 11:43:01AM +0200, Esben Haabendal wrote:
> From: Esben Haabendal <eha@deif.com>
> 
> Make sure to call reinit_completion() before dma is started to avoid race
> condition where reinit_completion() is called after complete() and before
> wait_for_completion_timeout().
> 
> Signed-off-by: Esben Haabendal <eha@deif.com>
> Fixes: ce1a78840ff7 ("i2c: imx: add DMA support for freescale i2c driver")
> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Applied to for-current and added stable, thanks!

Uwe, do you have comments for the other patches, too?


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Re: [PATCH v2 2/4] i2c: imx: Fix race condition in dma read

[Uwe Kleine-König]

On Mon, Jul 09, 2018 at 11:43:02AM +0200, Esben Haabendal wrote:
> From: Esben Haabendal <eha@deif.com>
> 
> This fixes a race condition, where the DMAEN bit ends up being set after
> I2C slave has transmitted a byte following the dummy read.  When that
> happens, an interrupt is generated instead, and no DMA request is generated
> to kickstart the DMA read, and a timeout happens after DMA_TIMEOUT (1 sec).
> 
> Fixed by setting the DMAEN bit before the dummy read.
> 
> Signed-off-by: Esben Haabendal <eha@deif.com>
> ---
>  drivers/i2c/busses/i2c-imx.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 39cfd98c7b23..d86f152176a4 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -668,9 +668,6 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
>  	struct imx_i2c_dma *dma = i2c_imx->dma;
>  	struct device *dev = &i2c_imx->adapter.dev;
>  
> -	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> -	temp |= I2CR_DMAEN;
> -	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
>  
>  	dma->chan_using = dma->chan_rx;
>  	dma->dma_transfer_dir = DMA_DEV_TO_MEM;
> @@ -810,6 +807,11 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
>  	if ((msgs->len - 1) || block_data)
>  		temp &= ~I2CR_TXAK;
>  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +	if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data) {
> +		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> +		temp |= I2CR_DMAEN;
> +		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +	}

Does this need to be a separate write to the I2CR register? Just before
the if there is temp written to this register, so probably this can be
changed to just:

	if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data)
		temp |= I2CR_DMAEN;

when moved before up one line.

I don't find documentation for the LS processors where this
register is described though (and the imx family doesn't seem to support
DMA for i2c).

Other than that this looks reasonable and warrants a

	Fixes: ce1a78840ff7 ("i2c: imx: add DMA support for freescale i2c driver")

.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Re: [PATCH v2 3/4] i2c: imx: Simplify stopped state tracking

[Uwe Kleine-König]

On Mon, Jul 09, 2018 at 11:43:03AM +0200, Esben Haabendal wrote:
> From: Esben Haabendal <eha@deif.com>
> 
> Always update the stopped state when busy status have been checked.
> This is identical to what was done before, with the exception of error
> handling.
> Without this change, some errors cause the stopped state to be left in
> incorrect state in i2c_imx_stop(), i2c_imx_dma_read(), i2c_imx_read() and
> i2c_imx_xfer().
> 
> Signed-off-by: Esben Haabendal <eha@deif.com>
> ---
>  drivers/i2c/busses/i2c-imx.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index d86f152176a4..1db8e6790afc 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -421,10 +421,14 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
>  			return -EAGAIN;
>  		}
>  
> -		if (for_busy && (temp & I2SR_IBB))
> +		if (for_busy && (temp & I2SR_IBB)) {
> +			i2c_imx->stopped = 0;
>  			break;
> -		if (!for_busy && !(temp & I2SR_IBB))
> +		}
> +		if (!for_busy && !(temp & I2SR_IBB)) {
> +			i2c_imx->stopped = 1;
>  			break;
> +		}

Would it make sense to assign to ->stopped independent of for_busy?

>  		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
>  			dev_dbg(&i2c_imx->adapter.dev,
>  				"<%s> I2C bus is busy\n", __func__);
> @@ -538,7 +542,6 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
>  	result = i2c_imx_bus_busy(i2c_imx, 1);
>  	if (result)
>  		return result;
> -	i2c_imx->stopped = 0;
>  
>  	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
>  	temp &= ~I2CR_DMAEN;
> @@ -569,7 +572,6 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
>  
>  	if (!i2c_imx->stopped) {
>  		i2c_imx_bus_busy(i2c_imx, 0);
> -		i2c_imx->stopped = 1;
>  	}

The braces can go away here.
>  
>  	/* Disable I2C controller */

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Re: [PATCH v2 4/4] arm: dts: ls1021a: Enable I2C DMA support

[Uwe Kleine-König]

Hello,

expanding Cc a bit to include Shawn and the kernel teams of Pengutronix
and NXP.

On Mon, Jul 09, 2018 at 11:43:04AM +0200, Esben Haabendal wrote:
> From: Esben Haabendal <eha@deif.com>
> 
> Gives substantial performance improvement for transfers larger than 16
> bytes (DMA_THRESHOLD).  Smaller transfers are unaffected.
> 
> Signed-off-by: Esben Haabendal <eha@deif.com>
> ---
>  arch/arm/boot/dts/ls1021a.dtsi | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/ls1021a.dtsi b/arch/arm/boot/dts/ls1021a.dtsi
> index c55d479971cc..1e5640701c65 100644
> --- a/arch/arm/boot/dts/ls1021a.dtsi
> +++ b/arch/arm/boot/dts/ls1021a.dtsi
> @@ -363,6 +363,8 @@
>  			interrupts = <GIC_SPI 88 IRQ_TYPE_LEVEL_HIGH>;
>  			clock-names = "i2c";
>  			clocks = <&clockgen 4 1>;
> +			dma-names = "tx", "rx";
> +			dmas = <&edma0 1 39>, <&edma0 1 38>;
>  			status = "disabled";
>  		};
>  
> @@ -374,6 +376,8 @@
>  			interrupts = <GIC_SPI 89 IRQ_TYPE_LEVEL_HIGH>;
>  			clock-names = "i2c";
>  			clocks = <&clockgen 4 1>;
> +			dma-names = "tx", "rx";
> +			dmas = <&edma0 1 37>, <&edma0 1 36>;
>  			status = "disabled";
>  		};
>  
> @@ -385,6 +389,8 @@
>  			interrupts = <GIC_SPI 90 IRQ_TYPE_LEVEL_HIGH>;
>  			clock-names = "i2c";
>  			clocks = <&clockgen 4 1>;
> +			dma-names = "tx", "rx";
> +			dmas = <&edma0 1 35>, <&edma0 1 34>;
>  			status = "disabled";
>  		};

This is a bit orthogonal to the other changes in this series and needs
at least an ack from Shawn. Looks ok in my eyes.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Re: [PATCH v2 2/4] i2c: imx: Fix race condition in dma read

[Esben Haabendal]

Uwe Kleine-König <u.kleine-koenig@pengutronix.de> writes:

> On Mon, Jul 09, 2018 at 11:43:02AM +0200, Esben Haabendal wrote:
>> From: Esben Haabendal <eha@deif.com>
>> 
>> This fixes a race condition, where the DMAEN bit ends up being set after
>> I2C slave has transmitted a byte following the dummy read.  When that
>> happens, an interrupt is generated instead, and no DMA request is generated
>> to kickstart the DMA read, and a timeout happens after DMA_TIMEOUT (1 sec).
>> 
>> Fixed by setting the DMAEN bit before the dummy read.
>> 
>> Signed-off-by: Esben Haabendal <eha@deif.com>
>> ---
>>  drivers/i2c/busses/i2c-imx.c | 8 +++++---
>>  1 file changed, 5 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> index 39cfd98c7b23..d86f152176a4 100644
>> --- a/drivers/i2c/busses/i2c-imx.c
>> +++ b/drivers/i2c/busses/i2c-imx.c
>> @@ -668,9 +668,6 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
>>  	struct imx_i2c_dma *dma = i2c_imx->dma;
>>  	struct device *dev = &i2c_imx->adapter.dev;
>>  
>> -	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
>> -	temp |= I2CR_DMAEN;
>> -	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
>>  
>>  	dma->chan_using = dma->chan_rx;
>>  	dma->dma_transfer_dir = DMA_DEV_TO_MEM;
>> @@ -810,6 +807,11 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
>>  	if ((msgs->len - 1) || block_data)
>>  		temp &= ~I2CR_TXAK;
>>  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
>> +	if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data) {
>> +		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
>> +		temp |= I2CR_DMAEN;
>> +		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
>> +	}
>
> Does this need to be a separate write to the I2CR register? Just before
> the if there is temp written to this register, so probably this can be
> changed to just:
>
> 	if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data)
> 		temp |= I2CR_DMAEN;
>
> when moved before up one line.

Sure, that is clearly better.

> I don't find documentation for the LS processors where this
> register is described though (and the imx family doesn't seem to support
> DMA for i2c).

Yes, unfortunately, I think the LS1021A reference manual requires NDA.

> Other than that this looks reasonable and warrants a
>
> 	Fixes: ce1a78840ff7 ("i2c: imx: add DMA support for freescale i2c driver")

I will add that.

/Esben

Re: [PATCH v2 3/4] i2c: imx: Simplify stopped state tracking

[Esben Haabendal]

Uwe Kleine-König <u.kleine-koenig@pengutronix.de> writes:

> On Mon, Jul 09, 2018 at 11:43:03AM +0200, Esben Haabendal wrote:
>> From: Esben Haabendal <eha@deif.com>
>> 
>> Always update the stopped state when busy status have been checked.
>> This is identical to what was done before, with the exception of error
>> handling.
>> Without this change, some errors cause the stopped state to be left in
>> incorrect state in i2c_imx_stop(), i2c_imx_dma_read(), i2c_imx_read() and
>> i2c_imx_xfer().
>> 
>> Signed-off-by: Esben Haabendal <eha@deif.com>
>> ---
>>  drivers/i2c/busses/i2c-imx.c | 12 ++++++------
>>  1 file changed, 6 insertions(+), 6 deletions(-)
>> 
>> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> index d86f152176a4..1db8e6790afc 100644
>> --- a/drivers/i2c/busses/i2c-imx.c
>> +++ b/drivers/i2c/busses/i2c-imx.c
>> @@ -421,10 +421,14 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
>>  			return -EAGAIN;
>>  		}
>>  
>> -		if (for_busy && (temp & I2SR_IBB))
>> +		if (for_busy && (temp & I2SR_IBB)) {
>> +			i2c_imx->stopped = 0;
>>  			break;
>> -		if (!for_busy && !(temp & I2SR_IBB))
>> +		}
>> +		if (!for_busy && !(temp & I2SR_IBB)) {
>> +			i2c_imx->stopped = 1;
>>  			break;
>> +		}
>
> Would it make sense to assign to ->stopped independent of for_busy?

What do you mean?

Assigning to ->stopped on each check for I2SR_IBB in loop, independent
of the for_busy argument?  I don't think so.  The additional assignments
would be to the same value as it is set to already.

>>  		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
>>  			dev_dbg(&i2c_imx->adapter.dev,
>>  				"<%s> I2C bus is busy\n", __func__);
>> @@ -538,7 +542,6 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
>>  	result = i2c_imx_bus_busy(i2c_imx, 1);
>>  	if (result)
>>  		return result;
>> -	i2c_imx->stopped = 0;
>>  
>>  	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
>>  	temp &= ~I2CR_DMAEN;
>> @@ -569,7 +572,6 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
>>  
>>  	if (!i2c_imx->stopped) {
>>  		i2c_imx_bus_busy(i2c_imx, 0);
>> -		i2c_imx->stopped = 1;
>>  	}
>
> The braces can go away here.

Will do.

/Esben

Re: [PATCH v2 3/4] i2c: imx: Simplify stopped state tracking

[Uwe Kleine-König]

On Thu, Aug 09, 2018 at 02:06:43PM +0200, Esben Haabendal wrote:
> Uwe Kleine-König <u.kleine-koenig@pengutronix.de> writes:
> 
> > On Mon, Jul 09, 2018 at 11:43:03AM +0200, Esben Haabendal wrote:
> >> From: Esben Haabendal <eha@deif.com>
> >> 
> >> Always update the stopped state when busy status have been checked.
> >> This is identical to what was done before, with the exception of error
> >> handling.
> >> Without this change, some errors cause the stopped state to be left in
> >> incorrect state in i2c_imx_stop(), i2c_imx_dma_read(), i2c_imx_read() and
> >> i2c_imx_xfer().
> >> 
> >> Signed-off-by: Esben Haabendal <eha@deif.com>
> >> ---
> >>  drivers/i2c/busses/i2c-imx.c | 12 ++++++------
> >>  1 file changed, 6 insertions(+), 6 deletions(-)
> >> 
> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> >> index d86f152176a4..1db8e6790afc 100644
> >> --- a/drivers/i2c/busses/i2c-imx.c
> >> +++ b/drivers/i2c/busses/i2c-imx.c
> >> @@ -421,10 +421,14 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
> >>  			return -EAGAIN;
> >>  		}
> >>  
> >> -		if (for_busy && (temp & I2SR_IBB))
> >> +		if (for_busy && (temp & I2SR_IBB)) {
> >> +			i2c_imx->stopped = 0;
> >>  			break;
> >> -		if (!for_busy && !(temp & I2SR_IBB))
> >> +		}
> >> +		if (!for_busy && !(temp & I2SR_IBB)) {
> >> +			i2c_imx->stopped = 1;
> >>  			break;
> >> +		}
> >
> > Would it make sense to assign to ->stopped independent of for_busy?
> 
> What do you mean?
> 
> Assigning to ->stopped on each check for I2SR_IBB in loop, independent
> of the for_busy argument?  I don't think so.  The additional assignments
> would be to the same value as it is set to already.

Currently you have:

	if (for_busy && (temp & I2SR_IBB)) {
		i2c_imx->stopped = 0;
		break;
	}

	if (!for_busy && !(temp & I2SR_IBB)) {
		i2c_imx->stopped = 1;
		break;
	}

The semantic of this is the same (apart from always updating .stopped)
but is imho easier:

	i2c_imx->stopped = !(temp & I2SR_IBB);

	if (for_busy != i2c_imx->stopped)
		break;

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Re: [PATCH v2 3/4] i2c: imx: Simplify stopped state tracking

[Esben Haabendal]

Uwe Kleine-König <u.kleine-koenig@pengutronix.de> writes:

> On Thu, Aug 09, 2018 at 02:06:43PM +0200, Esben Haabendal wrote:
>> Uwe Kleine-König <u.kleine-koenig@pengutronix.de> writes:
>> 
>> > On Mon, Jul 09, 2018 at 11:43:03AM +0200, Esben Haabendal wrote:
>> >> From: Esben Haabendal <eha@deif.com>
>> >> 
>> >> Always update the stopped state when busy status have been checked.
>> >> This is identical to what was done before, with the exception of error
>> >> handling.
>> >> Without this change, some errors cause the stopped state to be left in
>> >> incorrect state in i2c_imx_stop(), i2c_imx_dma_read(), i2c_imx_read() and
>> >> i2c_imx_xfer().
>> >> 
>> >> Signed-off-by: Esben Haabendal <eha@deif.com>
>> >> ---
>> >>  drivers/i2c/busses/i2c-imx.c | 12 ++++++------
>> >>  1 file changed, 6 insertions(+), 6 deletions(-)
>> >> 
>> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> >> index d86f152176a4..1db8e6790afc 100644
>> >> --- a/drivers/i2c/busses/i2c-imx.c
>> >> +++ b/drivers/i2c/busses/i2c-imx.c
>> >> @@ -421,10 +421,14 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
>> >>  			return -EAGAIN;
>> >>  		}
>> >>  
>> >> -		if (for_busy && (temp & I2SR_IBB))
>> >> +		if (for_busy && (temp & I2SR_IBB)) {
>> >> +			i2c_imx->stopped = 0;
>> >>  			break;
>> >> -		if (!for_busy && !(temp & I2SR_IBB))
>> >> +		}
>> >> +		if (!for_busy && !(temp & I2SR_IBB)) {
>> >> +			i2c_imx->stopped = 1;
>> >>  			break;
>> >> +		}
>> >
>> > Would it make sense to assign to ->stopped independent of for_busy?
>> 
>> What do you mean?
>> 
>> Assigning to ->stopped on each check for I2SR_IBB in loop, independent
>> of the for_busy argument?  I don't think so.  The additional assignments
>> would be to the same value as it is set to already.
>
> Currently you have:
>
> 	if (for_busy && (temp & I2SR_IBB)) {
> 		i2c_imx->stopped = 0;
> 		break;
> 	}
>
> 	if (!for_busy && !(temp & I2SR_IBB)) {
> 		i2c_imx->stopped = 1;
> 		break;
> 	}
>
> The semantic of this is the same (apart from always updating .stopped)
> but is imho easier:
>
> 	i2c_imx->stopped = !(temp & I2SR_IBB);
>
> 	if (for_busy != i2c_imx->stopped)
> 		break;

Yes, that should work also.
Shorter, but IMHO a bit more convoluted to read.
Let me know if I should send a new version with this change.

/Esben

Re: [PATCH v2 3/4] i2c: imx: Simplify stopped state tracking

[Uwe Kleine-König]

Hello Esben,

On Fri, Aug 10, 2018 at 11:25:34AM +0200, Esben Haabendal wrote:
> Uwe Kleine-König <u.kleine-koenig@pengutronix.de> writes:
> > Currently you have:
> >
> > 	if (for_busy && (temp & I2SR_IBB)) {
> > 		i2c_imx->stopped = 0;
> > 		break;
> > 	}
> >
> > 	if (!for_busy && !(temp & I2SR_IBB)) {
> > 		i2c_imx->stopped = 1;
> > 		break;
> > 	}
> >
> > The semantic of this is the same (apart from always updating .stopped)
> > but is imho easier:
> >
> > 	i2c_imx->stopped = !(temp & I2SR_IBB);
> >
> > 	if (for_busy != i2c_imx->stopped)
> > 		break;
> 
> Yes, that should work also.
> Shorter, but IMHO a bit more convoluted to read.
> Let me know if I should send a new version with this change.

unless someone else chimes in I'd say keep it as is. I'd prefer my
variant, but I accept that this is something subjective.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |