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@sang-engineering.com
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@ragnatech.se
sh_mobile_i2c_xfer_dma(pd);/* Enable all interrupts to begin with */
2.11.0