[PATCH 4/4] i3c: mipi-i3c-hci: Use own DMA bounce buffer management for I2C transfers

[Frank Li]

On Thu, Jul 31, 2025 at 05:14:20PM +0300, Jarkko Nikula wrote:
> Stop using I2C DMA-safe API for two reasons:
> - Not needed if driver is using PIO mode.
> - DMA transfers needs a properly sized receive bounce buffer when the

s/a properly sized/word align sized/

>   device DMA is IOMMU mapped causing needless double bounce buffering in

when use IOMMU, which causing ...

Frank
>   that case.
>
> Cc: Billy Tsai <billy_tsai at aspeedtech.com>
> Signed-off-by: Jarkko Nikula <jarkko.nikula at linux.intel.com>
> ---
>  drivers/i3c/master/mipi-i3c-hci/core.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
> index b2977b6ac9f7..7a467ef65787 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/core.c
> +++ b/drivers/i3c/master/mipi-i3c-hci/core.c
> @@ -348,7 +348,7 @@ static int i3c_hci_i2c_xfers(struct i2c_dev_desc *dev,
>  		return -ENOMEM;
>
>  	for (i = 0; i < nxfers; i++) {
> -		xfer[i].data = i2c_get_dma_safe_msg_buf(&i2c_xfers[i], 1);
> +		xfer[i].data = i2c_xfers[i].buf;
>  		xfer[i].data_len = i2c_xfers[i].len;
>  		xfer[i].rnw = i2c_xfers[i].flags & I2C_M_RD;
>  		hci->cmd->prep_i2c_xfer(hci, dev, &xfer[i]);
> @@ -374,10 +374,6 @@ static int i3c_hci_i2c_xfers(struct i2c_dev_desc *dev,
>  	}
>
>  out:
> -	for (i = 0; i < nxfers; i++)
> -		i2c_put_dma_safe_msg_buf(xfer[i].data, &i2c_xfers[i],
> -					 ret ? false : true);
> -
>  	hci_free_xfer(xfer, nxfers);
>  	return ret;
>  }
> --
> 2.47.2
>
>
> --
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