linux-kernel - [PATCH 7/8] arm64: update arch_zone_dma_bits to fine tune dma-direct min mask

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Date:   Wed, 31 Jul 2019 17:47:50 +0200
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     catalin.marinas@....com, hch@....de, wahrenst@....net,
        marc.zyngier@....com, Robin Murphy <robin.murphy@....com>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     phill@...pberryi.org, f.fainelli@...il.com, will@...nel.org,
        robh+dt@...nel.org, eric@...olt.net, mbrugger@...e.com,
        nsaenzjulienne@...e.de, akpm@...ux-foundation.org,
        frowand.list@...il.com, m.szyprowski@...sung.com,
        linux-rpi-kernel@...ts.infradead.org
Subject: [PATCH 7/8] arm64: update arch_zone_dma_bits to fine tune dma-direct min mask

With the introduction of ZONE_DMA in arm64 devices are not forced to
support 32 bit DMA masks. We have to inform dma-direct of this
limitation whenever it happens.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
---

 arch/arm64/mm/init.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index f5279ef85756..b809f3259340 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -22,6 +22,7 @@
 #include <linux/of_fdt.h>
 #include <linux/dma-mapping.h>
 #include <linux/dma-contiguous.h>
+#include <linux/dma-direct.h>
 #include <linux/efi.h>
 #include <linux/swiotlb.h>
 #include <linux/vmalloc.h>
@@ -439,10 +440,14 @@ void __init arm64_memblock_init(void)
 
 	early_init_fdt_scan_reserved_mem();
 
-	if (IS_ENABLED(CONFIG_ZONE_DMA))
+	if (IS_ENABLED(CONFIG_ZONE_DMA)) {
 		arm64_dma_phys_limit = max_zone_dma_phys();
-	else
+
+		if (arm64_dma_phys_limit)
+			arch_zone_dma_bits = ilog2(arm64_dma_phys_limit) + 1;
+	} else {
 		arm64_dma_phys_limit = 0;
+	}
 
 	/* 4GB maximum for 32-bit only capable devices */
 	if (IS_ENABLED(CONFIG_ZONE_DMA32))
-- 
2.22.0