Re: [PATCH] i2c: imx: Only DMA messages with I2C_M_DMA_SAFE flag set

[Oleksij Rempel <o.rempel@pengutronix.de>]

On Thu, Nov 10, 2022 at 12:59:02AM +0100, Andrew Lunn wrote:
> Recent changes to the DMA code has resulting in the IMX driver failing
> I2C transfers when the buffer has been vmalloc. Only perform DMA
> transfers if the message has the I2C_M_DMA_SAFE flag set, indicating
> the client is providing a buffer which is DMA safe.
> 
> This is a minimal fix for stable. The I2C core provides helpers to
> allocate a bounce buffer. For a fuller fix the master should make use
> of these helpers.
> 
> Fixes: 4544b9f25e70 ("dma-mapping: Add vmap checks to dma_map_single()")
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

> ---
>  drivers/i2c/busses/i2c-imx.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 3082183bd66a..fc70920c4dda 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1132,7 +1132,8 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
>  	int i, result;
>  	unsigned int temp;
>  	int block_data = msgs->flags & I2C_M_RECV_LEN;
> -	int use_dma = i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data;
> +	int use_dma = i2c_imx->dma && msgs->flags & I2C_M_DMA_SAFE &&
> +		msgs->len >= DMA_THRESHOLD && !block_data;
>  
>  	dev_dbg(&i2c_imx->adapter.dev,
>  		"<%s> write slave address: addr=0x%x\n",
> @@ -1298,7 +1299,8 @@ static int i2c_imx_xfer_common(struct i2c_adapter *adapter,
>  			result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg, atomic);
>  		} else {
>  			if (!atomic &&
> -			    i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD)
> +			    i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD &&
> +				msgs[i].flags & I2C_M_DMA_SAFE)
>  				result = i2c_imx_dma_write(i2c_imx, &msgs[i]);
>  			else
>  				result = i2c_imx_write(i2c_imx, &msgs[i], atomic);
> -- 
> 2.37.2
> 
> 

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