Hi Wolfram,
On 2017-07-18 12:23:38 +0200, Wolfram Sang wrote:
> This ensures that we fall back to PIO if the buffer is too small for DMA
> being useful. Otherwise, we use DMA. A bounce buffer might be applied if
> the original message buffer is not DMA safe
>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-sh_mobile.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
> index 2e097d97d258bc..19f45bcd9b35ca 100644
> --- a/drivers/i2c/busses/i2c-sh_mobile.c
> +++ b/drivers/i2c/busses/i2c-sh_mobile.c
> @@ -145,6 +145,7 @@ struct sh_mobile_i2c_data {
> struct dma_chan *dma_rx;
> struct scatterlist sg;
> enum dma_data_direction dma_direction;
> + u8 *bounce_buf;
> };
>
> struct sh_mobile_dt_config {
> @@ -548,6 +549,8 @@ static void sh_mobile_i2c_dma_callback(void *data)
> pd->pos = pd->msg->len;
> pd->stop_after_dma = true;
>
> + i2c_release_dma_bounce_buf(pd->msg, pd->bounce_buf);
> +
> iic_set_clr(pd, ICIC, 0, ICIC_TDMAE | ICIC_RDMAE);
> }
>
> @@ -595,6 +598,7 @@ static void sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data *pd)
> struct dma_async_tx_descriptor *txdesc;
> dma_addr_t dma_addr;
> dma_cookie_t cookie;
> + u8 *dma_buf = pd->bounce_buf ?: pd->msg->buf;
This looked funny and I had to look it up, I learnt something new today
:-)
>
> if (PTR_ERR(chan) == -EPROBE_DEFER) {
> if (read)
> @@ -608,7 +612,7 @@ static void sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data *pd)
> if (IS_ERR(chan))
> return;
>
> - dma_addr = dma_map_single(chan->device->dev, pd->msg->buf, pd->msg->len, dir);
> + dma_addr = dma_map_single(chan->device->dev, dma_buf, pd->msg->len, dir);
> if (dma_mapping_error(chan->device->dev, dma_addr)) {
> dev_dbg(pd->dev, "dma map failed, using PIO\n");
> return;
> @@ -665,7 +669,7 @@ static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg,
> pd->pos = -1;
> pd->sr = 0;
>
> - if (pd->msg->len > 8)
> + if (i2c_check_msg_for_dma(pd->msg, 8, &pd->bounce_buf) == 0)
Maybe the 8 should be declared in a define to explain the value, like
you do in patch 4/4?
This nitpick aside:
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> sh_mobile_i2c_xfer_dma(pd);
>
> /* Enable all interrupts to begin with */
> --
> 2.11.0
>
--
Regards,
Niklas Söderlund
