[U-Boot] [PATCH] ppc44x: config GPIOs for USB on canyonlands board

[Feng Kan]

On Fri, Sep 24, 2010 at 10:43 AM, Wolfgang Denk <wd at denx.de> wrote:
> Dear Feng Kan,
>
> In message <AANLkTin-rbM0NDqZmZKCYp45-m9S+3H_Fb7DwzzEHkUw at mail.gmail.com> you wrote:
>>
>> FKAN: Dear Wolfgang, is the symmetry needed here? If a user
>> plan to use the usb, he will trigger the function. Otherwise, on
>> a stop what value would we put it back to.
>
> Design rules say:
>
>        Shall initialize only such peripherals used by U-Boot itself,
>        and must deinitialize them after use. Note that especially the
>        deinitialization is mandatory!
>
FKAN: I agree, thanks. However, this conflict with one of your other
rule "Don't make U-Boot slow". If another software entity wish to use
the GPIO after, the code would deinit to gpio state and the
other init would init gpio to the same state. Essentially doubling the
code doing the same thing.

> Isn't this GPI reset to the initial values part of the
> deinitialization sequence?

FKAN: In this case, gpio is double muxed in functionality. Do we need
to remember state if the gpio is tri-muxed?

>
> Best regards,
>
> Wolfgang Denk
>
> --
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
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