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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: robh+dt@kernel.org, catalin.marinas@arm.com, hch@lst.de,
	ardb@kernel.org, linux-kernel@vger.kernel.org
Cc: robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org,
	linux-rpi-kernel@lists.infradead.org, jeremy.linton@arm.com,
	iommu@lists.linux-foundation.org, devicetree@vger.kernel.org,
	Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
	Will Deacon <will@kernel.org>
Subject: [PATCH v2 4/5] arm64: mm: Dynamically resize zone_dma_bits based on system's constraints
Date: Sat, 10 Oct 2020 17:12:34 +0200	[thread overview]
Message-ID: <20201010151235.20585-5-nsaenzjulienne@suse.de> (raw)
In-Reply-To: <20201010151235.20585-1-nsaenzjulienne@suse.de>

With the help of of_dma_safe_phys_limit() we can get the topmost
physical address accessible for DMA to the whole system and use that
information to properly setup zone_dma_bits.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 arch/arm64/include/asm/processor.h | 1 +
 arch/arm64/mm/init.c               | 5 ++---
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index fce8cbecd6bc..c09d3f1a9a6b 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -97,6 +97,7 @@
 
 extern phys_addr_t arm64_dma_phys_limit;
 #define ARCH_LOW_ADDRESS_LIMIT	(arm64_dma_phys_limit - 1)
+#define ZONE_DMA_BITS_DEFAULT	32
 
 struct debug_info {
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 0eca5865dcb1..5934df93bf4d 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -42,8 +42,6 @@
 #include <asm/tlb.h>
 #include <asm/alternative.h>
 
-#define ARM64_ZONE_DMA_BITS	30
-
 /*
  * We need to be able to catch inadvertent references to memstart_addr
  * that occur (potentially in generic code) before arm64_memblock_init()
@@ -196,7 +194,8 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
 	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
 
 #ifdef CONFIG_ZONE_DMA
-	zone_dma_bits = ARM64_ZONE_DMA_BITS;
+	zone_dma_bits = min(zone_dma_bits,
+			    (unsigned int)ilog2(of_dma_safe_phys_limit()));
 
 	if (IS_ENABLED(CONFIG_ACPI)) {
 		extern unsigned int acpi_iort_get_zone_dma_size(void);
-- 
2.28.0


  parent reply	other threads:[~2020-10-10 23:08 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-10 15:12 [PATCH v2 0/5] arm64: Default to 32-bit wide ZONE_DMA Nicolas Saenz Julienne
2020-10-10 15:12 ` [PATCH v2 1/5] arm64: mm: Move zone_dma_bits initialization into zone_sizes_init() Nicolas Saenz Julienne
2020-10-12 11:37   ` Catalin Marinas
2020-10-12 14:23     ` Ard Biesheuvel
2020-10-10 15:12 ` [PATCH v2 2/5] of/address: Introduce of_dma_lower_bus_limit() Nicolas Saenz Julienne
2020-10-11  7:47   ` Ard Biesheuvel
2020-10-14 11:34     ` Nicolas Saenz Julienne
2020-10-12 15:25   ` Rob Herring
2020-10-14 11:52     ` Nicolas Saenz Julienne
2020-10-14 12:23       ` Rob Herring
2020-10-10 15:12 ` [PATCH v2 3/5] dma-direct: Turn zone_dma_bits default value into a define Nicolas Saenz Julienne
2020-10-10 15:12 ` Nicolas Saenz Julienne [this message]
2020-10-10 15:12 ` [PATCH v2 5/5] mm: Update DMA zones description Nicolas Saenz Julienne

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