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 <chenzho...@huawei.com> --- 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; -- 2.20.1
