[PATCH v2] arm64: mm: fix DMA zone when dma-ranges is missing

[Marek Szyprowski]

On 28.08.2024 11:51, Baruch Siach wrote:
> Some platforms, like Rockchip RK3568 based Odroid M1, do not provide DMA
> limits information in device-tree dma-ranges property. Still some device
> drivers set DMA limit that relies on DMA zone at low 4GB memory area.
> Until commit ba0fb44aed47 ("dma-mapping: replace zone_dma_bits by
> zone_dma_limit"), zone_sizes_init() restricted DMA zone to low 32-bit.
>
> Restore DMA zone 32-bit limit when the platform provides no DMA bus
> limit information.
>
> Fixes: ba0fb44aed47 ("dma-mapping: replace zone_dma_bits by zone_dma_limit")
> Reported-by: Marek Szyprowski <m.szyprowski at samsung.com>
> Link: https://lore.kernel.org/r/53d988b1-bdce-422a-ae4e-158f305ad703@samsung.com
> Suggested-by: Robin Murphy <robin.murphy at arm.com>
> Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>
> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> ---
> This should go via the dma-mapping tree that contains the fixed commit.
>
> Marek, can you test on Odroid M1? Thanks.


Works fine!

Tested-by: Marek Szyprowski <m.szyprowski at samsung.com>


> v2:
>
>    * Directly check whether platform provides DMA bus limit (Robin)
>
>    * Add Link tag
> ---
>   arch/arm64/mm/init.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index bfb10969cbf0..5710129b8033 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -116,6 +116,9 @@ 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;
> +
>   	return min(zone_limit, memblock_end_of_DRAM() - 1) + 1;
>   }
>   

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland