[PATCH] i2c i.MX: Fix divider table

[s.hauer@pengutronix.de (Sascha Hauer)]

On Thu, Jul 05, 2012 at 11:36:27PM +0530, Shubhrajyoti Datta wrote:
> On Thu, Jul 5, 2012 at 6:40 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > Measurements on i.MX1 and i.MX53 have shown that the divider values
> > in the datasheets are wrong.
> How were the measurements made?

With an oscilloscope measuring the period length. This is probably not
very exact, but the current values are way off. We had 350KHz instead
of 380KHz (best possible divider) on an i.MX53. Funny enough some
divider values really match the ones in the datasheet.

BTW I'm pretty sure the input frequency to the core is calculated
correctly as it's the same clock that also drives the timer.

> 
> > the values from first, third and fourth
> > column were all measured to be 8 higher than in the datasheet. It
> > should be safe to assume that the SoCs between i.MX1 and i.MX53 behave
> > the same as the i2c unit is unchanged since the i.MX1.
> 
> Also does it vary board to board or is fixed by the ip?
> What I mean is that the external cap etc.

The clock is derived from an internal SoC clock, I don't think this can
be influenced that much by external components. I did not test different
boards, but two board with different SoCs.

Let's see what the IC guys tell us.

Sascha

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