linux-kernel - [PATCH 3.16 208/233] i2c: imx: Use correct function to write to register

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Date:   Sat, 09 Sep 2017 22:47:15 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Michail Georgios Etairidis" <m.etairidis@...k-ipc.com>,
        "Fugang Duan" <fugang.duan@....com>,
        "Wolfram Sang" <wsa@...-dreams.de>,
        "Uwe Kleine-König" <u.kleine-koenig@...gutronix.de>
Subject: [PATCH 3.16 208/233] i2c: imx: Use correct function to write to
 register

3.16.48-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Michail Georgios Etairidis <m.etairidis@...k-ipc.com>

commit 6c782a5ea56a799658e213a78dc1455264938afa upstream.

The i2c-imx driver incorrectly uses readb()/writeb() to read and
write to the appropriate registers when performing a repeated start.
The appropriate imx_i2c_read_reg()/imx_i2c_write_reg() functions
should be used instead. Performing a repeated start results in
a kernel panic. The platform is imx.

Signed-off-by: Michail G Etairidis <m.etairidis@...k-ipc.com>
Fixes: ce1a78840ff7 ("i2c: imx: add DMA support for freescale i2c driver")
Fixes: 054b62d9f25c ("i2c: imx: fix the i2c bus hang issue when do repeat restart")
Acked-by: Fugang Duan <fugang.duan@....com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
[bwh: Backported to 3.16: drop changes in i2c_imx_dma_read()]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -542,9 +542,9 @@ static int i2c_imx_read(struct imx_i2c_s
 				 * the first read operation, otherwise the first read cost
 				 * one extra clock cycle.
 				 */
-				temp = readb(i2c_imx->base + IMX_I2C_I2CR);
+				temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
 				temp |= I2CR_MTX;
-				writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+				imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
 			}
 		} else if (i == (msgs->len - 2)) {
 			dev_dbg(&i2c_imx->adapter.dev,