Re: [PATCH] i2c: bcm283x: fix ending of transfer in case of NACK

[Sascha Hauer <sha@pengutronix.de>]

On Wed, Jul 20, 2022 at 12:33:13PM +0200, Daniel Brát wrote:
> Fixes an issue where the driver in case of NACK error would not properly
> terminate the tranfer, resulting in BSC not sending the STOP condition
> until just before the next xfer.
> 
> Signed-off-by: Daniel Brát <danek.brat@gmail.com>
> ---
>  drivers/i2c/busses/i2c-bcm283x.c | 23 +++++++++++++++--------
>  1 file changed, 15 insertions(+), 8 deletions(-)

Applied, thanks

Sascha

> 
> diff --git a/drivers/i2c/busses/i2c-bcm283x.c b/drivers/i2c/busses/i2c-bcm283x.c
> index 097f73d983..fdba3b91bd 100644
> --- a/drivers/i2c/busses/i2c-bcm283x.c
> +++ b/drivers/i2c/busses/i2c-bcm283x.c
> @@ -147,7 +147,7 @@ static int bcm283x_i2c_msg_xfer(struct bcm283x_i2c *bcm_i2c,
>  
>  		if (ret) {
>  			dev_err(dev, "timeout: 10bit read initilization\n");
> -			return ret;
> +			goto out;
>  		}
>  		if (reg_s & BSC_S_ERR)
>  			goto nack;
> @@ -178,7 +178,7 @@ static int bcm283x_i2c_msg_xfer(struct bcm283x_i2c *bcm_i2c,
>  
>  			if (ret) {
>  				dev_err(dev, "timeout: waiting for data in FIFO\n");
> -				return ret;
> +				goto out;
>  			}
>  			if (reg_s & BSC_S_ERR)
>  				goto nack;
> @@ -197,7 +197,7 @@ static int bcm283x_i2c_msg_xfer(struct bcm283x_i2c *bcm_i2c,
>  
>  			if (ret) {
>  				dev_err(dev, "timeout: waiting for space in FIFO\n");
> -				return ret;
> +				goto out;
>  			}
>  			if (reg_s & BSC_S_ERR)
>  				goto nack;
> @@ -216,16 +216,23 @@ static int bcm283x_i2c_msg_xfer(struct bcm283x_i2c *bcm_i2c,
>  
>  	if (ret) {
>  		dev_err(dev, "timeout: waiting for transfer to end\n");
> -		return ret;
> +		goto out;
>  	}
>  	if (reg_s & BSC_S_ERR)
>  		goto nack;
> -	writel(BSC_S_DONE | BSC_S_ERR | BSC_S_CLKT, &bcm_i2c->regs->s);
> -	writel(BSC_C_CLEAR1 | BSC_C_I2CEN, &bcm_i2c->regs->c);
> -	return 0;
> +	goto out;
>  nack:
>  	dev_dbg(dev, "device with addr %x didn't ACK\n", msg->addr);
> -	return -EREMOTEIO;
> +	writel(BSC_S_ERR, &bcm_i2c->regs->s);
> +	timeout = calc_byte_timeout_us(bcm_i2c->bitrate);
> +	// Wait for end of transfer so BSC has time to send STOP condition
> +	readl_poll_timeout(&bcm_i2c->regs->s, reg_s, ~reg_s & BSC_S_TA, timeout);
> +	ret = -EREMOTEIO;
> +out:
> +	// Return to default state for next xfer
> +	writel(BSC_S_DONE | BSC_S_ERR | BSC_S_CLKT, &bcm_i2c->regs->s);
> +	writel(BSC_C_CLEAR1 | BSC_C_I2CEN, &bcm_i2c->regs->c);
> +	return ret;
>  }
>  
>  static int bcm283x_i2c_xfer(struct i2c_adapter *adapter,
> -- 
> 2.37.0
> 
> 
> 

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