On Mon, Jul 07, 2008 at 11:28:43AM +1000, David Gibson wrote: > > This function is surely needed in every case I considered so far. I am > > just sceptical if the boot-loader can determine a correct parentoffset > > all alone (which one of the two I2C busses is the correct one?). This is > > Hrm. "all alone". It's not clear to me what else there could be that > would have more information than the bootloader.
What I meant is that all the information a bootloader has may not be
sufficent. To solve this, some additional infos could be added to the
tree. In this case, it could be a few aliases.
> > What I encoded using "external-name" is where possible fragments
> > _could_ be added to. Something like a mount-point. The boot-loader
> > decides if and what could be mounted there. As an "/aliases" node is
> > already in use, I would favour to add such mount-points there.
>
> Hrm. I'm not convinced that the mount point model is actually a good
> one. I would have thought that one of the most common things to graft
> would be extra optional devices onto a bus. In this case there's no
> specific "mountpoint" the device could be attached at any valid
> address on the bus in question.
Maybe I am really missing something here, but what is the bus in
question? How do you tell from such an entry
[EMAIL PROTECTED]
device_type="rtc";
compatible="nxp,pcf8563";
reg=<0x51>;
};
if it is connected to "/pci/pci_bridge/isa" as in mpc8548cds.dts or to
"/soc5200/[EMAIL PROTECTED]" as in pcm030.dts? The latter even has another
I2C-bus [EMAIL PROTECTED] which could also be a possibility. This is why I'd
like
to encode the fragment as:
i2c_0 {
[EMAIL PROTECTED]
device_type="rtc";
compatible="nxp,pcf8563";
reg=<0x51>;
};
};
with i2c_0 being an alias to the proper bus. Maybe I should add that I
am _not_ assuming that the fragment is obtained from the bus which wants to
have devices added. That is, one I2C-eeprom may contain data about
additional devices on PCI.
Kind regards,
Wolfram
--
Dipl.-Ing. Wolfram Sang | http://www.pengutronix.de
Pengutronix - Linux Solutions for Science and Industry
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