[U-Boot] [RFC] gpio command: return value on write, additional actions

[Detlev Zundel <dzu@denx.de>]

Hi Andreas,

> I'd say clear/set/toggle are changeable, don't see any legit
> return-value-usage here. For 100% backward compatibility, one could
> leave them as they are and use 0|1 as new actions with return 0, as
> proposed.
>
> So these variants:
>   gpio clear|0 => set to output, write 0, return success
>   gpio set|1   => set to output, write 1, return success
>   gpio toggle  => (set to output), toggle output, return success
>   gpio input   => set to input, return pin value
>   gpio value   => return current pin/latch/whatever value

I'd propose to fix the commands to be sensible now.  Actually I believe
that they should not be in heavy use "in the wild" and so we should take
the opportunity and declare the current behaviour as buggy and fix it.
Rather now than later ;)

Actually I would expect the "output" commands to return true when they
were able to do what was requestes from them, i.e. drive the requested
value to the output.  I guess this cannot be done in the general case,
but for a "weak output" that can be read back, this would be the most
sensible thing to do.

Cheers
  Detlev

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