linux-kernel - [PATCH 4.16 116/279] i2c: sprd: Fix the i2c count issue

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Date:   Mon, 18 Jun 2018 10:11:41 +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, Baolin Wang <baolin.wang@...aro.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.16 116/279] i2c: sprd: Fix the i2c count issue

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Baolin Wang <baolin.wang@...aro.org>

[ Upstream commit 2a010461207cc96bee5ab81748325dec1972976f ]

We found the I2C controller count register is unreliable sometimes,
that will cause I2C to lose data. Thus we can read the data count
from 'i2c_dev->count' instead of the I2C controller count register.

Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/i2c/busses/i2c-sprd.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/drivers/i2c/busses/i2c-sprd.c
+++ b/drivers/i2c/busses/i2c-sprd.c
@@ -368,13 +368,12 @@ static irqreturn_t sprd_i2c_isr_thread(i
 	struct sprd_i2c *i2c_dev = dev_id;
 	struct i2c_msg *msg = i2c_dev->msg;
 	bool ack = !(readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK);
-	u32 i2c_count = readl(i2c_dev->base + I2C_COUNT);
 	u32 i2c_tran;
 
 	if (msg->flags & I2C_M_RD)
 		i2c_tran = i2c_dev->count >= I2C_FIFO_FULL_THLD;
 	else
-		i2c_tran = i2c_count;
+		i2c_tran = i2c_dev->count;
 
 	/*
 	 * If we got one ACK from slave when writing data, and we did not
@@ -412,14 +411,13 @@ static irqreturn_t sprd_i2c_isr(int irq,
 {
 	struct sprd_i2c *i2c_dev = dev_id;
 	struct i2c_msg *msg = i2c_dev->msg;
-	u32 i2c_count = readl(i2c_dev->base + I2C_COUNT);
 	bool ack = !(readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK);
 	u32 i2c_tran;
 
 	if (msg->flags & I2C_M_RD)
 		i2c_tran = i2c_dev->count >= I2C_FIFO_FULL_THLD;
 	else
-		i2c_tran = i2c_count;
+		i2c_tran = i2c_dev->count;
 
 	/*
 	 * If we did not get one ACK from slave when writing data, then we