On Mon, Apr 30, 2012 at 12:36:09AM +0200, Marek Vasut wrote: > This patch implements DMA support into mxs-i2c. DMA transfers are now enabled > by > default, though it is possible for example for debugging purposes, to disable > them via i2c->dma_mode. > > Cc: Linux I2C <[email protected]> > Cc: Detlev Zundel <[email protected]> > Cc: Fabio Estevam <[email protected]> > Cc: Stefano Babic <[email protected]> > Cc: Wolfgang Denk <[email protected]> > Cc: Wolfram Sang <[email protected]>
Looks promising, will give it a shot this week! Thanks.
Very quick review.
> ---
> arch/arm/mach-mxs/devices/platform-mxs-i2c.c | 5 +
> arch/arm/mach-mxs/include/mach/devices-common.h | 1 +
> drivers/i2c/busses/i2c-mxs.c | 261
> +++++++++++++++++++++--
> 3 files changed, 245 insertions(+), 22 deletions(-)
>
> diff --git a/arch/arm/mach-mxs/devices/platform-mxs-i2c.c
> b/arch/arm/mach-mxs/devices/platform-mxs-i2c.c
> index 79222ec..a94f308 100644
> --- a/arch/arm/mach-mxs/devices/platform-mxs-i2c.c
> +++ b/arch/arm/mach-mxs/devices/platform-mxs-i2c.c
> @@ -14,6 +14,7 @@
> { \
> .id = _id, \
> .iobase = soc ## _I2C ## _id ## _BASE_ADDR, \
> + .dma = soc ## _DMA_I2C ## _id, \
> .errirq = soc ## _INT_I2C ## _id ## _ERROR, \
> .dmairq = soc ## _INT_I2C ## _id ## _DMA, \
> }
> @@ -37,6 +38,10 @@ struct platform_device *__init mxs_add_mxs_i2c(
> .end = data->iobase + SZ_8K - 1,
> .flags = IORESOURCE_MEM,
> }, {
> + .start = data->dma,
> + .end = data->dma,
> + .flags = IORESOURCE_DMA,
> + }, {
> .start = data->errirq,
> .end = data->errirq,
> .flags = IORESOURCE_IRQ,
> diff --git a/arch/arm/mach-mxs/include/mach/devices-common.h
> b/arch/arm/mach-mxs/include/mach/devices-common.h
> index f2e3839..791d99c 100644
> --- a/arch/arm/mach-mxs/include/mach/devices-common.h
> +++ b/arch/arm/mach-mxs/include/mach/devices-common.h
> @@ -80,6 +80,7 @@ mxs_add_gpmi_nand(const struct gpmi_nand_platform_data
> *pdata,
> struct mxs_mxs_i2c_data {
> int id;
> resource_size_t iobase;
> + resource_size_t dma;
> resource_size_t errirq;
> resource_size_t dmairq;
> };
You need to either split this and send via alkml or I need an ACK from
Shawn if it shall go in via I2C. You don't have Shawn on CC, please use
scripts/get_maintainer.pl on your patchesr; you have been missing
people/lists at least for the third time now.
> static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len)
> {
> - u32 data;
> + u32 data = 0;
Unrelated, useless change.
> int i;
> +
> + /*
> + * The MXS I2C DMA mode is prefered and enabled by default.
> + * The PIO mode is still supported, but should be used only
> + * for debuging purposes etc.
> + */
For exactness, should be "PIOQUEUE" instead of PIO. There is a PIO mode,
but we don't use it.
> + i2c->dma_mode = 1;
Have you measured the overhead of DMA? I'd still think that
if (MX23 || msg->len > 24)
do_dma
else
do_pioqueue
might be worth considered.
Regards,
Wolfram
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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