linux-kernel - Re: [PATCH v3] i2c: imx: when being a target, mark the last read as processed

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Date: Wed, 21 Feb 2024 21:58:23 +0100
From: Andi Shyti <andi.shyti@...nel.org>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: linux-i2c@...r.kernel.org, Corey Minyard <minyard@....org>, 
	Andrew Manley <andrew.manley@...lingtech.com>, Oleksij Rempel <o.rempel@...gutronix.de>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Fabio Estevam <festevam@...il.com>, 
	NXP Linux Team <linux-imx@....com>, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] i2c: imx: when being a target, mark the last read as
 processed

Hi Wolfram and Corey,

On Wed, Feb 21, 2024 at 08:27:13PM +0100, Wolfram Sang wrote:
> From: Corey Minyard <minyard@....org>
> 
> When being a target, NAK from the controller means that all bytes have
> been transferred. So, the last byte needs also to be marked as
> 'processed'. Otherwise index registers of backends may not increase.
> 
> Signed-off-by: Corey Minyard <minyard@....org>
> Tested-by: Andrew Manley <andrew.manley@...lingtech.com>
> Reviewed-by: Andrew Manley <andrew.manley@...lingtech.com>
> Reviewed-by: Oleksij Rempel <o.rempel@...gutronix.de>
> [wsa: fixed comment and commit message to properly describe the case]
> Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>

is this a fix?

Andi

> ---
> 
> Changes since v2:
> * updated commit message and comment
> 
> In the stalled discussion[1], it seems I couldn't make my suggestions
> clear. So, here are the changes how I meant them. I hope this can be
> agreed on.
> 
> [1] http://patchwork.ozlabs.org/project/linux-i2c/patch/20211112133956.655179-3-minyard@acm.org/
> 
>  drivers/i2c/busses/i2c-imx.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 88a053987403..60e813137f84 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -803,6 +803,11 @@ static irqreturn_t i2c_imx_slave_handle(struct imx_i2c_struct *i2c_imx,
>  		ctl &= ~I2CR_MTX;
>  		imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
>  		imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> +
> +		/* flag the last byte as processed */
> +		i2c_imx_slave_event(i2c_imx,
> +				    I2C_SLAVE_READ_PROCESSED, &value);
> +
>  		i2c_imx_slave_finish_op(i2c_imx);
>  		return IRQ_HANDLED;
>  	}
> -- 
> 2.43.0
>