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From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: linux-i2c@vger.kernel.org
Cc: Corey Minyard <minyard@acm.org>,
	Andrew Manley <andrew.manley@sealingtech.com>,
	Oleksij Rempel <o.rempel@pengutronix.de>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Andi Shyti <andi.shyti@kernel.org>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3] i2c: imx: when being a target, mark the last read as processed
Date: Wed, 21 Feb 2024 20:27:13 +0100
Message-ID: <20240221193013.14233-2-wsa+renesas@sang-engineering.com>
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From: Corey Minyard <minyard@acm.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@acm.org>
Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
[wsa: fixed comment and commit message to properly describe the case]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

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