> -----Original Message-----
> From: Wolfram Sang [mailto:[email protected]]
> Sent: Friday, October 03, 2014 3:55 PM
> To: Yuan Yao-B46683
> Cc: [email protected]; [email protected]; [email protected]; Duan
> Fugang-B38611; [email protected]; [email protected]; linux-
> [email protected]; [email protected]
> Subject: Re: [PATCH v8 1/2] i2c: imx: add DMA support for freescale i2c
> driver
> > -#include <linux/init.h>
> > -#include <linux/kernel.h>
> > -#include <linux/module.h>
> > +#include <linux/clk.h>
> > +#include <linux/completion.h>
> > +#include <linux/delay.h>
> > +#include <linux/dma-mapping.h>
> > +#include <linux/dmaengine.h>
> > +#include <linux/dmapool.h>
> > #include <linux/errno.h>
> > #include <linux/err.h>
> > #include <linux/interrupt.h>
> > -#include <linux/delay.h>
> > #include <linux/i2c.h>
> > +#include <linux/init.h>
> > #include <linux/io.h>
> > -#include <linux/sched.h>
> > -#include <linux/platform_device.h>
> > -#include <linux/clk.h>
> > -#include <linux/slab.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > #include <linux/of.h>
> > #include <linux/of_device.h>
> > +#include <linux/of_dma.h>
> > #include <linux/platform_data/i2c-imx.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/sched.h>
> > +#include <linux/slab.h>
>
> This is a seperate patch.
[Yuan Yao]
Here I just adjust the order of the include file as alphabetical order.
If it looks strange I can only add the include files about DMA.
>
>
> > + while (1) {
> > + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> > + if (temp & I2SR_ICF)
> > + break;
> > + if (time_after(jiffies, orig_jiffies +
> > + msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT))) {
> > + dev_dbg(dev, "<%s> Timeout\n", __func__);
> > + return -ETIMEDOUT;
> > + }
> > + schedule();
>
> That might have been asked before. Is there no interrupt for this?
>
[Yuan Yao] No, there is no interrupt.
After DMA callback, I must wait until the last byte transfer completely.
It's a very short time which less than 10us.
By the way, how about use udelay(10) instead of schedule()?
udelay(10) is waiting a appropriate time.
schedule() is waiting too long for i2c but may be good for whole system.
Can you give me some suggestion?
Thanks for your review.
Best Regards,
Yuan Yao
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