From: "Gerhard Pircher" <gerhard_pircher@gmx•net>
To: David Gibson <david@gibson•dropbear.id.au>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [RFC] AmigaOne device tree source v2
Date: Wed, 05 Sep 2007 13:54:19 +0200 [thread overview]
Message-ID: <20070905115419.321990@gmx.net> (raw)
In-Reply-To: <20070905024805.GE17189@localhost.localdomain>
-------- Original-Nachricht --------
> Datum: Wed, 5 Sep 2007 12:48:05 +1000
> Von: David Gibson <david@gibson•dropbear.id.au>
> An: Gerhard Pircher <gerhard_pircher@gmx•net>
> CC: Segher Boessenkool <segher@kernel•crashing.org>, linuxppc-dev@ozlabs•org
> Betreff: Re: [RFC] AmigaOne device tree source v2
> That looks totally bogus. Unlike Segher, I think there are a few
> cases where overlapping reg and ranges can make sense (PCI bridges
> where config space is accessed indirectly via MMIO registers which lie
> in the legacy ISA IO space is an example). But this doesn't look like
> such a case - it just looks like whoever did the device tree
> misunderstood the distinction between reg and ranges.
AmigaOne's PCI bridge implements PCI config with indirect addressing, but
not within the ISA I/O space. I just wanted to clear up the meaning of
this reg entry, because it looks like everyone interprets the OF spec a
little bit differently.
> > > PCI legacy I/O is not direct mapped: there is no legacy I/O on a
> > > PowerPC system bus. So, it can not be mentioned in the "ranges"
> > > property, but the PHB registers used to access it should be shown
> > > in the "reg" property. It could be a simple linear window (it
> > > sounds like it is here?), but it could for example also be
> > > implemented via an address/data register pair.
>
> Err... huh? The legacy IO space is assigned a block of addresses in
> 3-word "OF-PCI-space by the PCI binding. When that is translated into
> an MMIO range by the bridge, there's no reason that can't be encoded
> into the ranges property.
I defined the legacy I/O space together with the PCI I/O space in the
ranges property of the PCI node:
ranges = <01000000 0 00000000 fe000000 0 00c00000
The first 64k of this address space are mapped to ISA I/O in the PCI2ISA
bridge node.
> The whole damn point of the device tree is to avoid using this kind of
> non-local information "I know what the board type is over there, so it
> must be this PCI bridge over here". The node should have a compatible
> property which is sufficient to select the right bridge driver.
Yeah, I defined a compatible = "mai,articias"; property in the pci node.
Are there any naming conventions (maybe lower case only)?
> I think this is typically badly done at the moment, simply because PCI
> has historically been set up by the platform code, rather than by a
> "host bridge driver" in the mould of other drivers. I don't see that
> changing real soon, but that doesn't mean we shouldn't at least put
> enough information in the device tree to make it possible.
I agree (even if it means more work for me :-)
I'll post a revised version of the device tree.
Thanks!
Gerhard
--
GMX FreeMail: 1 GB Postfach, 5 E-Mail-Adressen, 10 Free SMS.
Alle Infos und kostenlose Anmeldung: http://www.gmx.net/de/go/freemail
next prev parent reply other threads:[~2007-09-05 11:54 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-31 17:50 [RFC] AmigaOne device tree source v2 Gerhard Pircher
2007-09-03 1:34 ` David Gibson
2007-09-03 8:41 ` Benjamin Herrenschmidt
2007-09-03 10:02 ` Segher Boessenkool
2007-09-03 10:12 ` David Gibson
2007-09-03 16:11 ` Gerhard Pircher
2007-09-03 22:52 ` Segher Boessenkool
2007-09-04 0:27 ` David Gibson
2007-09-06 13:31 ` Segher Boessenkool
2007-09-04 12:20 ` Gerhard Pircher
2007-09-06 13:41 ` Segher Boessenkool
2007-09-03 14:58 ` Gerhard Pircher
2007-09-03 22:32 ` Segher Boessenkool
2007-09-04 11:49 ` Gerhard Pircher
2007-09-05 2:48 ` David Gibson
2007-09-05 11:54 ` Gerhard Pircher [this message]
2007-09-06 14:00 ` Segher Boessenkool
2007-09-06 14:09 ` Sven Luther
2007-09-06 14:42 ` Segher Boessenkool
2007-09-06 13:56 ` Segher Boessenkool
2007-09-06 14:15 ` PCI I/O space -- reg or ranges? Scott Wood
2007-09-06 20:51 ` Gerhard Pircher
2007-09-06 21:01 ` Segher Boessenkool
2007-09-07 0:20 ` [RFC] AmigaOne device tree source v2 David Gibson
2007-09-06 13:36 ` Segher Boessenkool
2007-09-06 21:09 ` Gerhard Pircher
2007-09-07 0:21 ` David Gibson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070905115419.321990@gmx.net \
--to=gerhard_pircher@gmx$(echo .)net \
--cc=david@gibson$(echo .)dropbear.id.au \
--cc=linuxppc-dev@ozlabs$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox