From mboxrd@z Thu Jan 1 00:00:00 1970 From: msalter@redhat.com (Mark Salter) Date: Mon, 23 Jun 2014 01:05:40 -0400 Subject: [PATCH] arm64: fix CONFIG_ZONE_DMA on systems with no 32-bit addressable DRAM Message-ID: <1403499940-11258-1-git-send-email-msalter@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Commit 2d5a5612bc (arm64: Limit the CMA buffer to 32-bit if ZONE_DMA) forces the CMA buffer to be 32-bit addressable if CONFIG_ZONE_DMA is defined. This breaks CMA on platforms with no 32-bit addressable DRAM. This patch checks to make sure there is 32-bit addressable DRAM before setting the 32-bit limit. If there is none, no limit is placed on the CMA buffer. This allows a single kernel (with CONFIG_ZONE_DMA defined) to support platforms requiring the 32-bit limit and platforms with no 32-bit limit. Signed-off-by: Mark Salter --- arch/arm64/mm/init.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index c5415e2..2925576 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -149,8 +149,17 @@ void __init arm64_memblock_init(void) early_init_fdt_scan_reserved_mem(); /* 4GB maximum for 32-bit only capable devices */ - if (IS_ENABLED(CONFIG_ZONE_DMA)) + if (IS_ENABLED(CONFIG_ZONE_DMA)) { dma_phys_limit = dma_to_phys(NULL, DMA_BIT_MASK(32)) + 1; + /* + * If platform doesn't have DRAM within the dma_phys_limit, + * remove the limit altogether. This allows one kernel (with + * CONFIG_ZONE_DMA defined) to support platforms with 32-bit + * only devices and platforms with no 32-bit DRAM. + */ + if (dma_phys_limit <= memblock_start_of_DRAM()) + dma_phys_limit = 0; + } dma_contiguous_reserve(dma_phys_limit); memblock_allow_resize(); -- 1.8.3.1