[i2c] [PATCH] Is review of AT91 patch pending?

David Brownell david-b at pacbell.net
Fri Oct 19 23:57:34 CEST 2007


http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=4631/1

> > +static struct i2c_gpio_platform_data pdata = {
> > +	.sda_pin		= AT91_PIN_PA25,
> > +	.sda_is_open_drain	= 1,
> > +	.scl_pin		= AT91_PIN_PA26,
> > +	.scl_is_open_drain	= 1,
> > +	.udelay			= 2,		/* ~100 KHz */
>
> The i2c-gpio documentation says: SCL frequency is (500 / udelay) kHz.
> So that should be 250 kHz. Not sure if it's a good idea as not all I2C
> slaves may support it. Maybe you should set udelay to 5.

Except that when I measured it, that formula didn't work.
There's overhead other than the udelay.




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