On Fri, Jun 09, 2017 at 03:28:12PM +0200, Michail Georgios Etairidis wrote: > 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. please limit lines in the commit to 76 chars. > I am resubmitting this patch as the previous one was erroneous. This patch is based on the current upstream kernel code. > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > index 95ed171..54a47b4 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -734,9 +734,9 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, > * 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); These were introduced by commit ce1a78840ff7a authored by Yao Yuan. > } > msgs->buf[msgs->len-1] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); > > @@ -857,9 +857,9 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo > * 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); These were introduced by commit 054b62d9f25c9 authored by Fugang Duan. I added these two people to Cc:, maybe they are still at Freescale/NXP and can comment. imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); results in readb(i2c_imx->base + (reg << i2c_imx->hwdata->regshift)); where .regshift is 2 for imx and 0 for vf610. So the patch makes a difference on the former platforms only. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
