Messages in this thread | | | Subject | Re: [PATCH 1/2] arm64: mm: update the comments about ZONE_DMA | From | Nicolas Saenz Julienne <> | Date | Sat, 26 Dec 2020 11:35:58 +0100 |
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On Sat, 2020-12-26 at 11:35 +0800, Chen Zhou wrote: > Since patchset "arm64: Default to 32-bit wide ZONE_DMA", ZONE_DMA's > size is fine-tuned. In the absence of addressing limited masters, > ZONE_DMA will span the whole 32-bit address space, otherwise, in > the case of the Raspberry Pi 4, it'll only span the 30-bit address > space. Update the comments. > > Signed-off-by: Chen Zhou <chenzhou10@huawei.com> > ---
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> arch/arm64/mm/init.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 75addb36354a..7b9809e39927 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -53,10 +53,11 @@ s64 memstart_addr __ro_after_init = -1; > EXPORT_SYMBOL(memstart_addr); > > > /* > - * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA covers the first 1G of > - * memory as some devices, namely the Raspberry Pi 4, have peripherals with > - * this limited view of the memory. ZONE_DMA32 will cover the rest of the 32 > - * bit addressable memory area. > + * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA's size is fine-tuned. > + * In the absence of addressing limited masters, ZONE_DMA will span the > + * whole 32-bit address space, otherwise, in the case of the Raspberry Pi 4, > + * it'll only span the 30-bit address space. ZONE_DMA32 will cover the rest > + * of the 32 bit addressable memory area. > */ > phys_addr_t arm64_dma_phys_limit __ro_after_init; > static phys_addr_t arm64_dma32_phys_limit __ro_after_init;
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