From: Michael Ellerman <michael@ellerman•id.au>
To: qingtao.cao@windriver•com
Cc: mm-commits@vger•kernel.org,
Linuxppc-dev Development <linuxppc-dev@ozlabs•org>,
Paul Mackerras <paulus@samba•org>,
Kumar Gala <galak@gate•crashing.org>,
Doug Thompson <norsk5@yahoo•com>,
akpm@linux-foundation•org
Subject: Re: + edac-cpc925-mc-platform-device-setup.patch added to -mm tree
Date: Thu, 16 Apr 2009 12:14:14 +1000 [thread overview]
Message-ID: <1239848054.6572.20.camel@localhost> (raw)
In-Reply-To: <49E69098.6040903@windriver.com>
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On Thu, 2009-04-16 at 09:57 +0800, Harry Ciao wrote:
> Kumar Gala wrote:
> > On Apr 15, 2009, at 5:27 PM, akpm@linux-foundation•org wrote:
> >> arch/powerpc/kernel/prom_init.c | 33 +++++++++++++
> >> arch/powerpc/platforms/maple/setup.c | 59 +++++++++++++++++++++++++
> >> 2 files changed, 92 insertions(+)
> >>
> >> diff -puN
> >> arch/powerpc/kernel/prom_init.c~edac-cpc925-mc-platform-device-setup
> >> arch/powerpc/kernel/prom_init.c
> >> ---
> >> a/arch/powerpc/kernel/prom_init.c~edac-cpc925-mc-platform-device-setup
> >> +++ a/arch/powerpc/kernel/prom_init.c
> >> @@ -1947,8 +1947,40 @@ static void __init fixup_device_tree_map
> >> prom_setprop(isa, name, "ranges",
> >> isa_ranges, sizeof(isa_ranges));
> >> }
> >> +
> >> +#define CPC925_MC_START 0xf8000000
> >> +#define CPC925_MC_LENGTH 0x1000000
> >> +/* The values for memory-controller don't have right number of cells */
> >> +static void __init fixup_device_tree_maple_memory_controller(void)
> >> +{
> >
> > I don't see why this cant be part of the existing
> > fixup_device_tree_maple().
> >
> > I also find it odd we don't ensure we are running on a maple before we
> > apply this fixup.
> Hi Kumar,
>
> Thanks a lot for your concern.
>
> This newly added fixup for memory controller on Maple will be placed
> right after fixup_device_tree_maple(), both of them will be controlled
> by CONFIG_PPC_MAPLE, so there is no worry that it will be applied
> against anything other than Maple.
Hi Harry,
We regularly build a single kernel with multiple platforms enabled, so
just having it controlled by a CONFIG symbol is not sufficient. Someone
might build a kernel for MAPLE & PSERIES & ISERIES & CELL, so the maple
fixup needs to be careful it doesn't break the other platforms.
The existing maple fixup doesn't check if it's on a maple either, but it
is a bit more discerning about what it finds before it fixes things up.
Your code already checks that "reg" is 8 bytes long to start with, I
think if it also checks that #address-cells and #size-cells are == 2,
then it's pretty safe. Because at that point we know we have a node with
the right name, the reg property has a known value, and reg is short WRT
#cells.
> Meanwhile, it aims at fixup bad cell numbers for the memory controller,
> whereas the original fixup_device_tree_maple() aiming at fixing up the
> ISA controller on HT channel, we'd better separate them in different
> function IMHO.
I think I agree it's better as a separate routine. We could have a
firmware that doesn't need the original maple fixup (and so exits from
that routine early) but does need this one.
cheers
--
Michael Ellerman
OzLabs, IBM Australia Development Lab
wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)
We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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next prev parent reply other threads:[~2009-04-16 2:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200904152227.n3FMRmdm007192@imap1.linux-foundation.org>
2009-04-15 23:58 ` + edac-cpc925-mc-platform-device-setup.patch added to -mm tree Kumar Gala
2009-04-16 1:57 ` Harry Ciao
2009-04-16 2:14 ` Michael Ellerman [this message]
2009-04-16 3:40 ` Harry Ciao
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