[U-Boot] fsl_i2c: increase I2C timeout values and make them configurable

[Timur Tabi <timur@freescale.com>]

Joakim Tjernlund wrote:

> This calculation does not seem to match AN2919.

When I wrote the code, AN2919 was much smaller than what you have today.

> Suppose one used only Table 7(almost what we have if you exclude dfsr!= 1)
> Table 7 is valid for 1 <= dfsr <=5 so how about replacing the current dfsr
> with:
> #ifdef __PPC__
> 			u8 dfsr;
> 			dfsr = (5*(i2c_clk/1000))/(100000);
> 			if (dfsr > 5)
> 				dfsr = 5;
> 			if (!dfsr)
> 				dfsr = 1;
> 			debug("i2c_clk:%d, dfsr:%d\n", i2c_clk, dfsr);
> 			writeb(dfsr, &dev->dfsrr);	/* set default filter */
> #endif

The value of FDR is dependent on the value of DFSR, so if I calculate DFSR, I have to also calculate FDR.  This means the table goes away.  I'm okay with that (since my table is no longer a viable approach, it seems), but it's more work than I'm willing to do at the moment.  Especically since this is going to need a lot of testing before I'm willing to push it.

Another way of handling this is to edit the table so that it only includes values of DFSR between 1 and 5, which is (unfortunately) *every* entry with a DFSR != 1.

-- 
Timur Tabi
Linux kernel developer at Freescale