Dear Dong Aisheng, > On Fri, Jun 29, 2012 at 04:24:03PM +0800, Marek Vasut wrote: > > This patch implements DMA support into mxs-i2c. DMA transfers are now > > enabled via DT. The DMA operation is enabled by default. > > > > Signed-off-by: Marek Vasut <marex@xxxxxxx> > > Cc: Detlev Zundel <dzu@xxxxxxx> > > CC: Dong Aisheng <b29396@xxxxxxxxxxxxx> > > CC: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx> > > Cc: Linux ARM kernel <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx> > > Cc: linux-i2c@xxxxxxxxxxxxxxx > > CC: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> > > CC: Shawn Guo <shawn.guo@xxxxxxxxxx> > > Cc: Stefano Babic <sbabic@xxxxxxx> > > CC: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> > > Cc: Wolfgang Denk <wd@xxxxxxx> > > Cc: Wolfram Sang <w.sang@xxxxxxxxxxxxxx> > > --- > > > > Documentation/devicetree/bindings/i2c/i2c-mxs.txt | 4 + > > arch/arm/boot/dts/imx28.dtsi | 2 + > > drivers/i2c/busses/i2c-mxs.c | 267 > > +++++++++++++++++++-- 3 files changed, 251 insertions(+), 22 > > deletions(-) > > > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mxs.txt > > b/Documentation/devicetree/bindings/i2c/i2c-mxs.txt index > > d2bf750..9497ee0 100644 > > --- a/Documentation/devicetree/bindings/i2c/i2c-mxs.txt > > +++ b/Documentation/devicetree/bindings/i2c/i2c-mxs.txt > > > > @@ -5,6 +5,10 @@ Required properties: > > - reg: Should contain registers location and length > > - interrupts: Should contain ERROR and DMA interrupts > > - clock-frequency: desired I2C bus clock frequency in Hz. > > > > +- fsl,i2c-dma-channel: APBX DMA channel for the I2C > > Shoundn't this be optional? DMA channel? No, why? > > > + /* > > + * The last descriptor must have this callback, > > + * to finish the DMA transaction. > > + */ > > + desc->callback = mxs_i2c_dma_irq_callback; > > + desc->callback_param = i2c; > > + > > + /* Start the transfer. */ > > + dmaengine_submit(desc); > > + dma_async_issue_pending(i2c->dmach); > > + return 0; > > + > > +/* Read failpath. */ > > +read_init_dma_fail: > > + dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE); > > +select_init_dma_fail: > > + dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE); > > +select_init_pio_fail: > > + return 1; > > look strange why return 1; Because it failed. -Esomething might be better ? > > + > > + > > One more unnecessary line? > > > +/* Write failpath. */ > > +write_init_dma_fail: > > + dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE); > > +write_init_pio_fail: > > + return 1; > > +} > > + > > .. > > > @@ -291,6 +459,7 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, > > struct i2c_msg *msg, > > > > timeout: > > dev_dbg(i2c->dev, "Timeout!\n"); > > > > + mxs_i2c_dma_finish(i2c); > > Shared with pio? Doesn't dma_unmap_sg() call check if the buffer is there or not? Therefore it shouldn't have any effect on PIO ops. But it can be indeed if-ed. > > mxs_i2c_reset(i2c); > > return -ETIMEDOUT; > > > > } > > Regards > Dong Aisheng Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
