Comments on device tree for pcm030

[Juergen Beisert]

On Monday 09 June 2008 01:28, Grant Likely wrote:
> On Sun, Jun 8, 2008 at 1:08 PM, Jon Smirl <jonsmirl at gmail.com> wrote:
> > Why not a compatible field in the top of the tree? Then you wouldn't
> > need to list the boards in mpc5200_simple.c.
> >        compatible = "phytec,pcm030","simple-mpc5200";
>
> Here's the problem; what does compatible really mean at the board
> level?  Does it mean the board has 100% of the same capabilities?
> Does it mean that it uses the same chip?  Does it mean that the chip
> is configured in a particular way?  It is really hard to define what a
> compatible value means at the board level.  The meaning of compatible
> at the device level is very well defined, but that meaning does not
> extend well to the board level.
>
> Therefore, it is best to be conservative here and require a specific
> list of supported boards in platform code.
>
> Besides, it is really a Linux specific thing that is trying to be
> described.  In Linux, we've decided to support as many 5200 boards as
> possible using the same platform code, but that may not be true, or it
> may be a different set of boards, when a different OS is used.  To
> attempt to encode those decisions is overreaching the intent of using
> the device tree.
>
> > Device tree has an entry for AC97 on PSC1. I don't think the Phytec
> > module or carrier board has AC97 hardware.
>
> Might be a bug

NACK. The baseboard for the pcm030 CPU board has AC97 hardware connected to 
PSC1. And it plays audio...

> > The RTC chip says pcf8563, phytec doc says it is a pcf8564.
>
> Sounds like a bug

These devices are mostly the same. You can use the pcf8563 driver for the 
pcf8564.

> > There should be an i2c entry for the eeprom but I don't know the part
> > number for it.
>
> Yes, i2c devices should be described.

Its a 24C32.

I believe Wolfram has a newer OFtree for the pcm030 so I add him as CC.

Regards,
Juergen

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Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
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