Re: [PATCH] ARM: allow, but warn, when issuing ioremap() on RAM

[Felipe Contreras]

On Sat, Oct 9, 2010 at 12:21 PM, Russell King - ARM Linux
<linux@xxxxxxxxxxxxxxxx> wrote:
> static unsigned long reserve_mem(struct meminfo *mi, unsigned long size)
> {
> Â Â Â Âunsigned long addr = ~0;
> Â Â Â Âint i;
>
> Â Â Â Âfor (i = mi->nr_banks - 1; i >= 0; i--)
> Â Â Â Â Â Â Â Âif (mi->bank[i].size >= size) {
> Â Â Â Â Â Â Â Â Â Â Â Âmi->bank[i].size -= size;
> Â Â Â Â Â Â Â Â Â Â Â Âaddr = mi->bank[i].start + mi->bank[i].size;
> Â Â Â Â Â Â Â Â Â Â Â Âbreak;
> Â Â Â Â Â Â Â Â}
>
> Â Â Â Âreturn addr;
> }
>
> static void __init my_fixup(struct machine_desc *desc, struct tag *tags,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Âchar **cmdline, struct meminfo *mi)
> {
> Â Â Â Âomapfb_buffer_phys = reserve_mem(mi, 32*1048576);
> Â Â Â Âif (omapfb_buffer_phys == ~0)
> Â Â Â Â Â Â Â Âpr_warn("Unable to allocate omapfb buffer\n");
> }
>
> Then later:
>
> Â Â Â Âomapfb_buffer = ioremap(omapfb_buffer_phys, 32*1048576);
>
> That's a damned simple and direct implementation of exactly what I
> described, and results in something which is much more architecturally
> correct than what's going on today.

I tried this, it doesn't work.

At the time 'fixup' is called, 'meminfo' is empty; the tags haven't
been parsed. So my solution is to move the memblock_add() after
'reserve', and pass 'meminfo' as an argument:

--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -272,8 +272,6 @@ void __init arm_memblock_init(struct meminfo *mi,
struct machine_desc *mdesc)
        int i;

        memblock_init();
-       for (i = 0; i < mi->nr_banks; i++)
-               memblock_add(mi->bank[i].start, mi->bank[i].size);

        /* Register the kernel text, kernel data and initrd with memblock. */
 #ifdef CONFIG_XIP_KERNEL
@@ -295,7 +293,10 @@ void __init arm_memblock_init(struct meminfo *mi,
struct machine_desc *mdesc)

        /* reserve any platform specific memblock areas */
        if (mdesc->reserve)
-               mdesc->reserve();
+               mdesc->reserve(mi);
+
+       for (i = 0; i < mi->nr_banks; i++)
+               memblock_add(mi->bank[i].start, mi->bank[i].size);

        memblock_analyze();
        memblock_dump_all();

-- 
Felipe Contreras
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