On Thu, 2009-04-16 at 09:57 +0800, Harry Ciao wrote:
> Kumar Gala wrote:
> > On Apr 15, 2009, at 5:27 PM, a...@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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