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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: catalin.marinas@arm.com, hch@lst.de, wahrenst@gmx.net,
	marc.zyngier@arm.com, robh+dt@kernel.org,
	Robin Murphy <robin.murphy@arm.com>,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	linux-arch@vger.kernel.org, iommu@lists.linux-foundation.org,
	linux-mm@kvack.org, linux-riscv@lists.infradead.org,
	Marek Szyprowski <m.szyprowski@samsung.com>
Cc: phill@raspberryi.org, linux-s390@vger.kernel.org,
	f.fainelli@gmail.com, Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	frowand.list@gmail.com, linuxppc-dev@lists.ozlabs.org,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	linux-kernel@vger.kernel.org, eric@anholt.net, mbrugger@suse.com,
	Paul Mackerras <paulus@samba.org>,
	linux-rpi-kernel@lists.infradead.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	akpm@linux-foundation.org, will@kernel.org,
	nsaenzjulienne@suse.de
Subject: [PATCH v2 09/11] dma-direct: turn ARCH_ZONE_DMA_BITS into a variable
Date: Tue, 20 Aug 2019 16:58:17 +0200
Message-ID: <20190820145821.27214-10-nsaenzjulienne@suse.de> (raw)
In-Reply-To: <20190820145821.27214-1-nsaenzjulienne@suse.de>

Some architectures, notably arm64, are interested in tweaking this
depending on their runtime dma addressing limitations.

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

Changes in v2:
- Rename new variable to zone_dma_bits
- Update comment with Christoph's suggestion
- Remove old powerpc comment

 arch/powerpc/include/asm/page.h |  9 ---------
 arch/powerpc/mm/mem.c           | 16 +++++++++++-----
 arch/s390/include/asm/page.h    |  2 --
 arch/s390/mm/init.c             |  1 +
 include/linux/dma-direct.h      |  2 ++
 kernel/dma/direct.c             | 13 ++++++-------
 6 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 0d52f57fca04..73668a21ae78 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -319,13 +319,4 @@ struct vm_area_struct;
 #endif /* __ASSEMBLY__ */
 #include <asm/slice.h>
 
-/*
- * Allow 30-bit DMA for very limited Broadcom wifi chips on many powerbooks.
- */
-#ifdef CONFIG_PPC32
-#define ARCH_ZONE_DMA_BITS 30
-#else
-#define ARCH_ZONE_DMA_BITS 31
-#endif
-
 #endif /* _ASM_POWERPC_PAGE_H */
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 9191a66b3bc5..2a69f87585df 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -31,6 +31,7 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/memremap.h>
+#include <linux/dma-direct.h>
 
 #include <asm/pgalloc.h>
 #include <asm/prom.h>
@@ -201,10 +202,10 @@ static int __init mark_nonram_nosave(void)
  * everything else. GFP_DMA32 page allocations automatically fall back to
  * ZONE_DMA.
  *
- * By using 31-bit unconditionally, we can exploit ARCH_ZONE_DMA_BITS to
- * inform the generic DMA mapping code.  32-bit only devices (if not handled
- * by an IOMMU anyway) will take a first dip into ZONE_NORMAL and get
- * otherwise served by ZONE_DMA.
+ * By using 31-bit unconditionally, we can exploit zone_dma_bits to inform the
+ * generic DMA mapping code.  32-bit only devices (if not handled by an IOMMU
+ * anyway) will take a first dip into ZONE_NORMAL and get otherwise served by
+ * ZONE_DMA.
  */
 static unsigned long max_zone_pfns[MAX_NR_ZONES];
 
@@ -237,9 +238,14 @@ void __init paging_init(void)
 	printk(KERN_DEBUG "Memory hole size: %ldMB\n",
 	       (long int)((top_of_ram - total_ram) >> 20));
 
+	if (IS_ENABLED(CONFIG_PPC32))
+		zone_dma_bits = 30;
+	else
+		zone_dma_bits = 31;
+
 #ifdef CONFIG_ZONE_DMA
 	max_zone_pfns[ZONE_DMA]	= min(max_low_pfn,
-				      1UL << (ARCH_ZONE_DMA_BITS - PAGE_SHIFT));
+				      1UL << (zone_dma_bits - PAGE_SHIFT));
 #endif
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 #ifdef CONFIG_HIGHMEM
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index 823578c6b9e2..a4d38092530a 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -177,8 +177,6 @@ static inline int devmem_is_allowed(unsigned long pfn)
 #define VM_DATA_DEFAULT_FLAGS	(VM_READ | VM_WRITE | \
 				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
 
-#define ARCH_ZONE_DMA_BITS	31
-
 #include <asm-generic/memory_model.h>
 #include <asm-generic/getorder.h>
 
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 20340a03ad90..bd98465b8b9f 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -118,6 +118,7 @@ void __init paging_init(void)
 
 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
 	sparse_init();
+	zone_dma_bits = 31;
 	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
 	max_zone_pfns[ZONE_DMA] = PFN_DOWN(MAX_DMA_ADDRESS);
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index adf993a3bd58..d03af3605460 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -5,6 +5,8 @@
 #include <linux/dma-mapping.h>
 #include <linux/mem_encrypt.h>
 
+extern unsigned int zone_dma_bits;
+
 #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
 #include <asm/dma-direct.h>
 #else
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 795c9b095d75..b23cd65f26e0 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -16,12 +16,11 @@
 #include <linux/swiotlb.h>
 
 /*
- * Most architectures use ZONE_DMA for the first 16 Megabytes, but
- * some use it for entirely different regions:
+ * Most architectures use ZONE_DMA for the first 16 Megabytes, but some use it
+ * it for entirely different regions. In that case the arch code needs to
+ * override the variable below for dma-direct to work properly.
  */
-#ifndef ARCH_ZONE_DMA_BITS
-#define ARCH_ZONE_DMA_BITS 24
-#endif
+unsigned int zone_dma_bits __ro_after_init = 24;
 
 static void report_addr(struct device *dev, dma_addr_t dma_addr, size_t size)
 {
@@ -69,7 +68,7 @@ static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
 	 * Note that GFP_DMA32 and GFP_DMA are no ops without the corresponding
 	 * zones.
 	 */
-	if (*phys_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+	if (*phys_mask <= DMA_BIT_MASK(zone_dma_bits))
 		return GFP_DMA;
 	if (*phys_mask <= DMA_BIT_MASK(32))
 		return GFP_DMA32;
@@ -387,7 +386,7 @@ int dma_direct_supported(struct device *dev, u64 mask)
 	u64 min_mask;
 
 	if (IS_ENABLED(CONFIG_ZONE_DMA))
-		min_mask = DMA_BIT_MASK(ARCH_ZONE_DMA_BITS);
+		min_mask = DMA_BIT_MASK(zone_dma_bits);
 	else
 		min_mask = DMA_BIT_MASK(32);
 
-- 
2.22.0

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  parent reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-20 14:58 [PATCH v2 00/11] Raspberry Pi 4 DMA addressing support Nicolas Saenz Julienne
2019-08-20 14:58 ` [PATCH v2 01/11] asm-generic: add dma_zone_size Nicolas Saenz Julienne
2019-08-26  7:09   ` Christoph Hellwig
2019-08-26 13:46     ` Nicolas Saenz Julienne
2019-08-28  9:44       ` Nicolas Saenz Julienne
2019-08-30 14:45       ` Catalin Marinas
2019-08-30 17:24         ` Nicolas Saenz Julienne
2019-09-02 13:01           ` Christoph Hellwig
2019-08-20 14:58 ` [PATCH v2 02/11] arm: use generic dma_zone_size Nicolas Saenz Julienne
2019-08-20 14:58 ` [PATCH v2 03/11] of/fdt: add of_fdt_machine_is_compatible function Nicolas Saenz Julienne
2019-08-20 17:16   ` Rob Herring
2019-08-20 17:27     ` Nicolas Saenz Julienne
2019-08-20 14:58 ` [PATCH v2 04/11] of/fdt: add early_init_dt_get_dma_zone_size() Nicolas Saenz Julienne
2019-08-20 17:14   ` Rob Herring
2019-08-20 14:58 ` [PATCH v2 05/11] arm64: mm: use arm64_dma_phys_limit instead of calling max_zone_dma_phys() Nicolas Saenz Julienne
2019-08-20 14:58 ` [PATCH v2 06/11] arm64: rename variables used to calculate ZONE_DMA32's size Nicolas Saenz Julienne
2019-08-20 14:58 ` [PATCH v2 07/11] arm64: re-introduce max_zone_dma_phys() Nicolas Saenz Julienne
2019-08-20 14:58 ` [PATCH v2 08/11] arm64: use both ZONE_DMA and ZONE_DMA32 Nicolas Saenz Julienne
2019-08-20 14:58 ` Nicolas Saenz Julienne [this message]
2019-08-26  7:05   ` [PATCH v2 09/11] dma-direct: turn ARCH_ZONE_DMA_BITS into a variable Christoph Hellwig
2019-08-26 11:33   ` Michael Ellerman
2019-08-20 14:58 ` [PATCH v2 10/11] arm64: edit zone_dma_bits to fine tune dma-direct min mask Nicolas Saenz Julienne
2019-08-26  7:06   ` Christoph Hellwig
2019-08-26 11:08     ` Nicolas Saenz Julienne
2019-08-27  7:03       ` Petr Tesarik
2019-08-20 14:58 ` [PATCH v2 11/11] mm: refresh ZONE_DMA and ZONE_DMA32 comments in 'enum zone_type' Nicolas Saenz Julienne
2019-08-26  7:07   ` Christoph Hellwig

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