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From:   Clark Wang <xiaoning.wang@nxp.com>
To:     aisheng.dong@nxp.com, shawnguo@kernel.org, s.hauer@pengutronix.de
Cc:     kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com,
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        linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 01/11] i2c: imx-lpi2c: directly retrun ISR when detect a NACK
Date:   Wed, 17 Mar 2021 14:53:49 +0800
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From: Gao Pan <pandy.gao@nxp.com>

A NACK flag in ISR means i2c bus error. In such codition,
there is no need to do read/write operation. It's better
to return ISR directly and then stop i2c transfer.

Signed-off-by: Gao Pan <pandy.gao@nxp.com>
Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
---
 drivers/i2c/busses/i2c-imx-lpi2c.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
index 9db6ccded5e9..bbf44ac95021 100644
--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@ -507,15 +507,17 @@ static irqreturn_t lpi2c_imx_isr(int irq, void *dev_id)
 	lpi2c_imx_intctrl(lpi2c_imx, 0);
 	temp = readl(lpi2c_imx->base + LPI2C_MSR);
 
+	if (temp & MSR_NDF) {
+		complete(&lpi2c_imx->complete);
+		goto ret;
+	}
+
 	if (temp & MSR_RDF)
 		lpi2c_imx_read_rxfifo(lpi2c_imx);
-
-	if (temp & MSR_TDF)
+	else if (temp & MSR_TDF)
 		lpi2c_imx_write_txfifo(lpi2c_imx);
 
-	if (temp & MSR_NDF)
-		complete(&lpi2c_imx->complete);
-
+ret:
 	return IRQ_HANDLED;
 }
 
-- 
2.25.1