[U-Boot] [PATCH 2/3] Reset interrupted i2c slaves (galaxy5200)

[Detlev Zundel]

Hello Heiko,

>>> Reset any i2c devices that may have been interrupted by a system reset.
>>> Normally this would be accomplished by clocking the line until SCL and SDA
>>> are released and then sending a start condtiion (From an Atmel datasheet).
>>> But since there is only write access to these lines on the MPC5200 we can
>>> only attempt to reset any slave devices by sending more start commands than
>>> bits the slave is attempting to transmit.
>> 
>> You may want to talk to Heiko (on CC) about this deblocking stuff.
>> Heiko implemented an algorithm which seems to work very good for a lot
>> of different cpu types.
>
> But this is realized for the bitbang driver, and actual only manufacturer
> (keymile) specific. 

I don't see a reason, why deblockiung an I2C bus should be manufacturer
specific...

> So, if we can use the I2C pins as GPIO, it is maybe
> an option, but a fast look in the mpc5200 users manual, didn;t show me
> a way for using the I2C pins as GPIO, so, we must implement a CPU
> specific (as we did it for the 83xx) way.
>
>> I think it may be worth to reuse what's available there.  And much more,
>> the algorithm Heiko has implemented has been thoroughly tested on actual
>> hardware whereas from your commit-msg it seems that your implementation
>> is more a theoretical one at the moment.
>
> As I understood Eric, there is only write access to the I2C pins, so
> we couldn;t use "my" deblocking mechanism. As Erics way is as the
> standard deblocking mechanism in the bitbang driver, I think, it is
> okay.

Ok, thanks for validating though!  Maybe we should add some
documentation notes about the various places where such things are done?

Cheers
  Detlev

-- 
The Speedo3 is very similar to other Intel network chips, that is to say
"apparently designed on a different planet".
                               -- drivers/net/eepro100.c in Linux source
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