diff options
| author | Baruch Siach <baruch@tkos.co.il> | 2024-09-01 09:12:34 +0300 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2024-09-03 10:25:36 +0300 |
| commit | 122c234ef4e182440f8a60490e9344bfc4e2b5e9 (patch) | |
| tree | 7fd4f014c919827764234b74b9dfc742fb08af44 /arch/arm64/mm | |
| parent | 334304ac2baca7f3e821c47cf5129d90e7a6b1e6 (diff) | |
arm64: mm: keep low RAM dma zone
Commit ba0fb44aed47 ("dma-mapping: replace zone_dma_bits by
zone_dma_limit") optimistically assumed that device-tree dma-ranges
property describes the system DMA limits. That assumption ignores DMA
limits of individual devices that are not encoded in device tree.
Commit 833bd284a45 ("arm64: mm: fix DMA zone when dma-ranges is
missing") fixed part of the problem for platforms that do not provide
dma-ranges at all. However platforms like SM8550-HDK provide DMA bus
limit, but have devices with stronger DMA limits.
of_dma_get_max_cpu_address() does not take device limitations into
account.
These platforms implicitly rely on DMA zone in low 32-bit RAM area.
Until we find a better way to figure out the optimal DMA zone range,
restore the low RAM DMA zone we had before commit ba0fb44aed47.
Fixes: ba0fb44aed47 ("dma-mapping: replace zone_dma_bits by zone_dma_limit")
Closes: https://lore.kernel.org/r/1a0c7282-63e0-4add-8e38-3abe3e0a8e2f@linaro.org
Reported-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-HDK
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'arch/arm64/mm')
| -rw-r--r-- | arch/arm64/mm/init.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 5710129b8033..eb76ac6d87c0 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -116,8 +116,14 @@ static void __init arch_reserve_crashkernel(void) static phys_addr_t __init max_zone_phys(phys_addr_t zone_limit) { - if (zone_limit == PHYS_ADDR_MAX) - zone_limit = U32_MAX; + /** + * Information we get from firmware (e.g. DT dma-ranges) describe DMA + * bus constraints. Devices using DMA might have their own limitations. + * Some of them rely on DMA zone in low 32-bit memory. Keep low RAM + * DMA zone on platforms that have RAM there. + */ + if (memblock_start_of_DRAM() < U32_MAX) + zone_limit = min(zone_limit, U32_MAX); return min(zone_limit, memblock_end_of_DRAM() - 1) + 1; } |