Re: [PATCH 1/4] i2c: rockchip: fix i2c stop condition

[Sascha Hauer <sha@pengutronix.de>]

On Fri, Sep 08, 2023 at 12:16:46PM +0200, Gerald Loacker wrote:
> The i2c bus gets disabled without sending a stop condition. This violates
> i2c timing on the clock line. Fix this and include all related functions
> (rk_i2c_send_start_bit, rk_i2c_send_stop_bit, rk_i2c_disable) onto the same
> level.
> 
> Signed-off-by: Gerald Loacker <gerald.loacker@wolfvision.net>
> ---
>  drivers/i2c/busses/i2c-rockchip.c | 21 ++++++++-------------
>  1 file changed, 8 insertions(+), 13 deletions(-)
> 
> @@ -387,6 +376,11 @@ static int rockchip_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
>  		struct i2c_msg *msg = &msgs[i];
>  
>  		dev_dbg(dev, "i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
> +
> +		ret = rk_i2c_send_start_bit(i2c);
> +		if (ret)
> +			break;
> +
>  		if (msg->flags & I2C_M_RD) {
>  			ret = rk_i2c_read(i2c, msg->addr, 0, 0, msg->buf,
>  					  msg->len);
> @@ -394,6 +388,9 @@ static int rockchip_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
>  			ret = rk_i2c_write(i2c, msg->addr, 0, 0, msg->buf,
>  					   msg->len);
>  		}
> +
> +		rk_i2c_send_stop_bit(i2c);
> +
>  		if (ret) {
>  			dev_dbg(dev, "i2c_write: error sending: %pe\n",
>  				ERR_PTR(ret));
> @@ -402,9 +399,7 @@ static int rockchip_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
>  		}
>  	}
>  
> -	rk_i2c_send_stop_bit(i2c);

I believe this is wrong. A stop bit should only be sent after the last
message, not after all messages.

Sascha

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