[PATCH v3 3/4] i2c: sh_mobile: use helper to decide if DMA is useful
From: Wolfram Sang <wsa+renesas@sang-engineering.com>
Date: 2017-07-18 10:25:37
Also in:
alsa-devel, linux-i2c, linux-iio, linux-media, linux-renesas-soc, lkml
Subsystem:
i2c subsystem, i2c subsystem host drivers, renesas r-car i2c drivers, the rest · Maintainers:
Wolfram Sang, Andi Shyti, Linus Torvalds
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; 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