From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> Sent: Tuesday, June 20, 2017 2:54 AM >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 > The patch seems fine. It should use .imx_i2c_read_reg() instead of readb(). Acked-by: Fugang Duan <fugang.duan@xxxxxxx> >-- >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
