Re: [PATCH v4 3/4] arm64: use both ZONE_DMA and ZONE_DMA32
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2019-09-08 21:27:19
Also in:
linux-mm, linux-riscv, lkml
On Fri, Sep 06, 2019 at 02:06:14PM +0200, Nicolas Saenz Julienne wrote:
quoted hunk ↗ jump to hunk
@@ -430,7 +454,7 @@ void __init arm64_memblock_init(void) high_memory = __va(memblock_end_of_DRAM() - 1) + 1; - dma_contiguous_reserve(arm64_dma32_phys_limit); + dma_contiguous_reserve(arm64_dma_phys_limit ? : arm64_dma32_phys_limit); } void __init bootmem_init(void)@@ -534,6 +558,7 @@ static void __init free_unused_memmap(void) void __init mem_init(void) { if (swiotlb_force == SWIOTLB_FORCE || + max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT) || max_pfn > (arm64_dma32_phys_limit >> PAGE_SHIFT)) swiotlb_init(1);
So here we want to initialise the swiotlb only if we need bounce buffers. Prior to this patch, we assumed that swiotlb is needed if max_pfn is beyond the reach of 32-bit devices. With ZONE_DMA, we need to lower this limit to arm64_dma_phys_limit. If ZONE_DMA is enabled, just comparing max_pfn with arm64_dma_phys_limit is sufficient since the dma32 one limit always higher. However, if ZONE_DMA is disabled, arm64_dma_phys_limit is 0, so we may initialise swiotlb unnecessarily. I guess you need a similar check to the dma_contiguous_reserve() above. With that: Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Unless there are other objections, I can queue this series for 5.5 in a few weeks time (too late for 5.4). -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel