From: marex@denx•de (Marek Vasut)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/2] MXS: Implement DMA support into mxs-i2c
Date: Fri, 29 Jun 2012 11:30:16 +0200 [thread overview]
Message-ID: <201206291130.17060.marex@denx.de> (raw)
In-Reply-To: <20120629091900.GJ5844@shlinux2.ap.freescale.net>
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@denx•de>
> > Cc: Detlev Zundel <dzu@denx•de>
> > CC: Dong Aisheng <b29396@freescale•com>
> > CC: Fabio Estevam <fabio.estevam@freescale•com>
> > Cc: Linux ARM kernel <linux-arm-kernel@lists•infradead.org>
> > Cc: linux-i2c at vger.kernel.org
> > CC: Sascha Hauer <s.hauer@pengutronix•de>
> > CC: Shawn Guo <shawn.guo@linaro•org>
> > Cc: Stefano Babic <sbabic@denx•de>
> > CC: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix•de>
> > Cc: Wolfgang Denk <wd@denx•de>
> > Cc: Wolfram Sang <w.sang@pengutronix•de>
> > ---
> >
> > 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
next prev parent reply other threads:[~2012-06-29 9:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-29 8:24 [PATCH 1/2] MXS: Set I2C timing registers for mxs-i2c Marek Vasut
2012-06-29 8:24 ` [PATCH 2/2] MXS: Implement DMA support into mxs-i2c Marek Vasut
2012-06-29 9:19 ` Dong Aisheng
2012-06-29 9:30 ` Marek Vasut [this message]
2012-06-29 9:38 ` Dong Aisheng
2012-06-29 10:02 ` Marek Vasut
2012-06-29 12:05 ` Dong Aisheng
2012-06-29 9:06 ` [PATCH 1/2] MXS: Set I2C timing registers for mxs-i2c Dong Aisheng
2012-06-29 9:33 ` Marek Vasut
2012-06-29 9:39 ` Dong Aisheng
2012-06-29 10:03 ` Marek Vasut
2012-06-29 11:47 ` Shawn Guo
-- strict thread matches above, loose matches on Subject: below --
2012-05-27 2:10 Marek Vasut
2012-05-27 2:10 ` [PATCH 2/2] MXS: Implement DMA support into mxs-i2c Marek Vasut
2012-06-06 3:47 ` Shawn Guo
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