linux-kernel - [PATCH 5.4 111/214] i2c: rcar: in slave mode, clear NACK earlier

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Date:   Tue,  1 Sep 2020 17:09:51 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Wolfram Sang <wsa@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 111/214] i2c: rcar: in slave mode, clear NACK earlier

From: Wolfram Sang <wsa+renesas@...g-engineering.com>

[ Upstream commit 914a7b3563b8fb92f976619bbd0fa3a4a708baae ]

Currently, a NACK in slave mode is set/cleared when SCL is held low by
the IP core right before the bit is about to be pushed out. This is too
late for clearing and then a NACK from the previous byte is still used
for the current one. Now, let's clear the NACK right after we detected
the STOP condition following the NACK.

Fixes: de20d1857dd6 ("i2c: rcar: add slave support")
Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
Signed-off-by: Wolfram Sang <wsa@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/i2c/busses/i2c-rcar.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 0b90aa0318df3..9c162a01a5849 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -587,6 +587,7 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
 	/* master sent stop */
 	if (ssr_filtered & SSR) {
 		i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value);
+		rcar_i2c_write(priv, ICSCR, SIE | SDBS); /* clear our NACK */
 		rcar_i2c_write(priv, ICSIER, SAR);
 		rcar_i2c_write(priv, ICSSR, ~SSR & 0xff);
 	}
-- 
2.25.1