Re: pxa300 - DDRAM base value

[Mike Rapoport]

Marek Vasut wrote:
> Dne Po 7. Äervna 2010 21:37:16 Mike Rapoport napsal(a):
> > > hi,
> > >       Now, I can able to boot after editing following files
> > > arch/arm/mach-pxa/Makefile.boot and
> > > arch/arm/mach/pxa/include/mach/memory.h (0x80000000 changed to
> > > 0xa0000000). My doubt is
> > > 1.why 0x80000000 (DDR phy address) is aliased to 0xa0000000 in pxa
> > > architecture?
> > > 2.In my development board two DDRAMs mapped at 0x80000000-0x88000000 and
> > > 0xc0000000-0xc8000000, how can I inform to kernel about this different
> > > bank and size?.
> > enable CONFIG_HIGHMEM
>
> Mike, that wont help him as he has PHYS_OFFSET=0xa0000000 . Selecting 
> CONFIG_HIGHMEM will only cause the pages for RAM below 0xa0000000 to have 
> incorrectly computated descriptor addresses (or maybe will be ignored).
>
> The page descriptors for RAM at PA 0xa0000000 are at VA 0xc0000000 + some offset 
> (there's an easy linear formula to compute their offset). Now if you feed that 
> formula with 0x80000000, the page descriptors will end below 0xc0000000, which 
> isn't a valid VA, therefore the descriptors will not be valid either (in the 
> better case, but it will hang the kernel at early stage anyway).
>
> Therefore there are two ways -- either use what I suggested earlier or wait 
> until the PHYS_OFFSET is dynamically computated (check Eric's patchset).

Not quite. I have it working with CONFIG_HIGHMEM, I've just forgotten 
about cm_x300_fixup:

static void __init cm_x300_fixup(struct machine_desc *mdesc, struct tag 
*tags,
                                 char **cmdline, struct meminfo *mi)
{
        /* Make sure that mi->bank[0].start = PHYS_ADDR */
        for (; tags->hdr.size; tags = tag_next(tags))
                if (tags->hdr.tag == ATAG_MEM &&
                        tags->u.mem.start == 0x80000000) {
                        tags->u.mem.start = 0xa0000000;
                        break;
                }
}


> Cheers
> > > My Boot loader details,
> > > ------------------------------
> > > =>bdi
> > > arch_number = 0x00000B04
> > > env_t       = 0x00000000
> > > boot_params = 0x80000100
> > > DRAM bank   = 0x00000000
> > > -> start    = 0x80000000
> > > -> size     = 0x08000000
> > > DRAM bank   = 0x00000001
> > > -> start    = 0xC0000000
> > > -> size     = 0x08000000
> > > ethaddr     = 08:00:3e:26:0a:5b
> > > ip_addr     = 192.168.0.21
> > > baudrate    = 115200 bps
> > > =>ver
> > > U-Boot 2010.03 (Jun 01 2010 - 14:27:43)
> > >
> > >
> > > With Thanks
> > > J.Balakrishnan
> > > _______________________________________________
> > > linux-arm-kernel mailing list
> > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel


--
Sincerely yours,
Mike.
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