| Message ID | 20170718102339.28726-4-wsa+renesas@sang-engineering.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 >
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 */
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(-)