[U-Boot-Users] [PATCH 1/1] Fix I2C for m547x/548x and m5445x processors.
Wolfgang Denk
wd at denx.de
Mon Jul 7 20:02:17 CEST 2008
In message <1215447465.12657.15.camel at 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.
> 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.
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
How many seconds are there in a year? If I tell you there are 3.155 x
10^7, you won't even try to remember it. On the other hand, who could
forget that, to within half a percent, pi seconds is a nanocentury.
- Tom Duff, Bell Labs
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