On Wed, Aug 6, 2014 at 3:30 PM, Al Cooper <alcooperx@xxxxxxxxx> wrote:
> __reserved_mem_reserve_reg() won't reserve memory if the base address
> is zero. This change removes the check for a base address of zero and
> allows it to be reserved.
>
> Allowing the first 4K of memory to be reserved will help solve a
> problem on some ARM systems where the the first 16K of memory is
> unused and becomes allocable memory. This will prevent this memory
> from being used for DMA by drivers like the USB OHCI driver which
> consider a physical address of zero to be illegal.
OHCI driver or hardware? I agree with the change, but really think
this should be fixed in the driver in the former case or a property of
the OHCI node in the latter.
Rob
>
> Signed-off-by: Al Cooper <alcooperx@xxxxxxxxx>
> ---
> drivers/of/fdt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 9aa012e..379ad4f 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -453,7 +453,7 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
> base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> size = dt_mem_next_cell(dt_root_size_cells, &prop);
>
> - if (base && size &&
> + if (size &&
> early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
> pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %ld MiB\n",
> uname, &base, (unsigned long)size / SZ_1M);
> --
> 1.9.0.138.g2de3478
>
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