Re: [PATCH] i2c: designware: deduce speed mode from device tree setting

[Mark Rutland <mark.rutland@arm.com>]

On Wed, Aug 20, 2014 at 01:36:18PM +0100, Wolfram Sang wrote:
> > > +
> > > +		ret = of_property_read_u32(pdev->dev.of_node,
> > > +					   "clock-frequency", &bus_rate);
> > > +		if (!ret && (bus_rate <= 100000))
> > > +			speed = DW_IC_CON_SPEED_STD;
> > 
> > This looks a bit odd.
> > 
> > If the device only supports two particular speeds why do we accept any
> > other speed in the clock-frequency property?
> 
> "clock-frequency" is the default binding for specifying i2c bus speeds
> today. Some controllers can be programmed to do various speeds, some can
> only do a set of fixed values.

Sure. My complaint was that the driver would accept invalid values.
That wasn't meant to be suggestion to use a property other than the
standard clock-freqeuncy.

> > Surely we should at least warn that something was off?
> 
> Yes, I was going to say the same until Romain's old patch showed up
> which does that.

Cool. Sounds like we can use Romain's patch to handle this then.

Cheers,
Mark.