[U-Boot-Users] [PATCH 1/1] Fix I2C for m547x/548x and m5445x processors.

Luigi 'Comio' Mantellini
2008-07-07T19:24:18Z

Il giorno lun, 07/07/2008 alle 20.02 +0200, Wolfgang Denk ha scritto:
> In message <1215447465.12657.15.camel@localhost> you wrote:
> >
> > I just extended the fsl_i2c.c driver that already uses a precomputed
>
> Yes, I know. I never understood what such a complicated driver for
> sich a simple protocol was good for, especially as we don't do
> multimegabytepersecond transfers over such a bus.
>

I agree with you. But I prefer to have a (too) complex working driver
instead an buggy driver. In other hands if m547x cpus have to use the
fsl_driver... this should be fixed in order to work fine. Otherwise the
HW i2c driver should be dropped from m57x/m5445x boards in order to
avoid to confuse the u-boot users/developers.

Today my HW-man ask me why the i2c bus ran at 1Mhz... The cause was that
I used the driver with confidence... too confidence...

> > table to setup the fsl i2c. I haven't invented these values but just
> > copied from the 547x and 5445x manuals. Furthermore, the h/w i2c is more
> > accurate that the simple bitbanging.
>
> Accurate? There is no requirement to be "accurate" anywhere in the
> I2C protocol. It is a simple, brain-dead protokol where timing is
> highly uncritical. And given that we need it to read a few bytes from
> EEPROM or RTC or similar I really see no benefit in using such a
> complicated driver.
>

I know :) but I like see 100kHz +/-0.01% when I configure 100kHz... I'm
kidding, of course. eheheh...
In the last time I preferred to disable i2c driver on all my
applications... I ask me why all embedded controller on the SoC that I'm
using are bugged... are the masks too expensive to work fine?

Ciao ciao

luigi

> Best regards,
>
> Wolfgang Denk
>

Ing. Luigi Mantellini
Industrie Dial Face S.p.A.
Via Canzo, 4
20068 Peschiera Borromeo (MI)
Tel.: +39 02 5167 2813
Fax: +39 02 5167 2459
E-mail: luigi.mantellini at idf-hit.com