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;
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)
sh_mobile_i2c_xfer_dma(pd);
/* Enable all interrupts to begin with */
--
2.11.0
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