From: Feng Tang Date: Thu, 12 Jun 2025 02:14:17 +0000 (+0800) Subject: dma-contiguous: hornor the cma address limit setup by user X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=aa807b9f22df2eee28593cbbabba0f93f4aa26c1;p=linux-block.git dma-contiguous: hornor the cma address limit setup by user When porting a cma related usage from x86_64 server to arm64 server, the "cma=4G@4G" setup failed on arm64. The reason is arm64 and some other architectures have specific physical address limit for reserved cma area, like 4GB due to the device's need for 32 bit dma. Actually lots of platforms of those architectures don't have this device dma limit, but still have to obey it, and are not able to reserve a huge cma pool. This situation could be improved by honoring the user input cma physical address than the arch limit. As when users specify it, they already knows what the default is which probably can't suit them. Suggested-by: Robin Murphy Signed-off-by: Feng Tang Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20250612021417.44929-1-feng.tang@linux.alibaba.com --- diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index 8df0dfaaca18..67af8a55185d 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -222,7 +222,10 @@ void __init dma_contiguous_reserve(phys_addr_t limit) if (size_cmdline != -1) { selected_size = size_cmdline; selected_base = base_cmdline; - selected_limit = min_not_zero(limit_cmdline, limit); + + /* Hornor the user setup dma address limit */ + selected_limit = limit_cmdline ?: limit; + if (base_cmdline + size_cmdline == limit_cmdline) fixed = true; } else {