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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: robh+dt@kernel.org, catalin.marinas@arm.com, hch@lst.de,
	robin.murphy@arm.com, devicetree@vger.kernel.org,
	iommu@lists.linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Cc: will@kernel.org, linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/4] arm64: Default to 32-bit ZONE_DMA
Date: Thu,  1 Oct 2020 18:17:39 +0200	[thread overview]
Message-ID: <20201001161740.29064-4-nsaenzjulienne@suse.de> (raw)
In-Reply-To: <20201001161740.29064-1-nsaenzjulienne@suse.de>

The Raspberry Pi 4 needs two DMA zones as some of its devices can only
DMA into the 30-bit physical address space. We solved that by creating
an extra ZONE_DMA covering the 30-bit. It turns out that creating extra
zones unnecessarily broke Kdump on large systems. So default to a single
32-bit wide ZONE_DMA and only define both zones if running on RPi4.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 arch/arm64/mm/init.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e1a69a618832..3c3f462466eb 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -43,8 +43,6 @@
 #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()
@@ -388,8 +386,14 @@ void __init arm64_memblock_init(void)
 	early_init_fdt_scan_reserved_mem();
 
 	if (IS_ENABLED(CONFIG_ZONE_DMA)) {
-		zone_dma_bits = ARM64_ZONE_DMA_BITS;
-		arm64_dma_phys_limit = max_zone_phys(ARM64_ZONE_DMA_BITS);
+		/*
+		 * early_init_dt_scan() might alter zone_dma_bits based on the
+		 * device's DT. Otherwise, have it cover the 32-bit address
+		 * space.
+		 */
+		if (zone_dma_bits == ZONE_DMA_BITS_DEFAULT)
+			zone_dma_bits = 32;
+		arm64_dma_phys_limit = max_zone_phys(zone_dma_bits);
 	}
 
 	if (IS_ENABLED(CONFIG_ZONE_DMA32))
-- 
2.28.0

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  parent reply	other threads:[~2020-10-01 16:18 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01 16:17 [PATCH 0/4] arm64: Default to 32-bit wide ZONE_DMA Nicolas Saenz Julienne
2020-10-01 16:17 ` [PATCH 1/4] of/fdt: Update zone_dma_bits when running in bcm2711 Nicolas Saenz Julienne
2020-10-01 17:15   ` Catalin Marinas
2020-10-01 17:23     ` Catalin Marinas
2020-10-01 17:31       ` Nicolas Saenz Julienne
2020-10-01 20:02         ` Rob Herring
2020-10-02 11:55         ` Catalin Marinas
2020-10-08 10:05           ` Nicolas Saenz Julienne
2020-10-08 10:13             ` Catalin Marinas
2020-10-08 19:43               ` Ard Biesheuvel
2020-10-09  3:59                 ` Jeremy Linton
2020-10-09  8:37                   ` Nicolas Saenz Julienne
2020-10-09  7:10             ` Christoph Hellwig
2020-10-09  7:37               ` Ard Biesheuvel
2020-10-09  8:36                 ` Nicolas Saenz Julienne
2020-10-09  9:13                   ` Ard Biesheuvel
2020-10-09 13:33                     ` Nicolas Saenz Julienne
2020-10-09 15:24                     ` Lorenzo Pieralisi
2020-10-09 16:23                       ` Ard Biesheuvel
2020-10-09 17:10                         ` Catalin Marinas
2020-10-10 10:36                           ` Ard Biesheuvel
2020-10-10 10:53                             ` Nicolas Saenz Julienne
2020-10-10 12:38                               ` Catalin Marinas
2020-10-12  6:47                           ` Christoph Hellwig
2020-10-12  8:47                             ` Catalin Marinas
2020-10-02  9:05   ` kernel test robot
2020-10-01 16:17 ` [PATCH 2/4] dma-direct: Turn zone_dma_bits default value into a define Nicolas Saenz Julienne
2020-10-01 16:17 ` Nicolas Saenz Julienne [this message]
2020-10-01 17:19   ` [PATCH 3/4] arm64: Default to 32-bit ZONE_DMA Catalin Marinas
2020-10-01 16:17 ` [PATCH 4/4] mm: Update DMA zones description Nicolas Saenz Julienne
2020-10-01 17:19   ` Catalin Marinas

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