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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: Robin Murphy <robin.murphy@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	bcm-kernel-feedback-list@broadcom.com,
	linux-rpi-kernel@lists.infradead.org,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Cc: hch@infradead.org, mbrugger@suse.com, f.fainelli@gmail.com,
	wahrenst@gmx.net, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
	Russell King <linux@armlinux.org.uk>
Subject: [PATCH RFC 3/5] ARM: let machines select dma-direct over arch's DMA implementation
Date: Mon, 14 Oct 2019 20:31:05 +0200	[thread overview]
Message-ID: <20191014183108.24804-4-nsaenzjulienne@suse.de> (raw)
In-Reply-To: <20191014183108.24804-1-nsaenzjulienne@suse.de>

A bounce buffering feature is already available in ARM, dmabounce.c, yet
it doesn't support high memory which some devices need. Instead of
fixing it, provide a means for devices to enable dma-direct, which is the
preferred way of doing DMA now days.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 arch/arm/include/asm/mach/arch.h | 1 +
 arch/arm/mm/init.c               | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index e7df5a822cab..3542bf502573 100644
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -33,6 +33,7 @@ struct machine_desc {
 #ifdef CONFIG_ZONE_DMA
 	phys_addr_t		dma_zone_size;	/* size of DMA-able area */
 #endif
+	bool			dma_direct;
 
 	unsigned int		video_start;	/* start of video RAM	*/
 	unsigned int		video_end;	/* end of video RAM	*/
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 0a63379a4d1a..556f70665353 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -19,6 +19,7 @@
 #include <linux/gfp.h>
 #include <linux/memblock.h>
 #include <linux/dma-contiguous.h>
+#include <linux/dma-direct.h>
 #include <linux/sizes.h>
 #include <linux/stop_machine.h>
 #include <linux/swiotlb.h>
@@ -119,6 +120,8 @@ void __init setup_dma_zone(const struct machine_desc *mdesc)
 	 */
 	if (IS_ENABLED(CONFIG_ARM_LPAE))
 		arm_dma_direct = true;
+	else
+		arm_dma_direct = mdesc->dma_direct;
 
 #ifdef CONFIG_ZONE_DMA
 	if (mdesc->dma_zone_size) {
@@ -126,7 +129,10 @@ void __init setup_dma_zone(const struct machine_desc *mdesc)
 		arm_dma_limit = PHYS_OFFSET + arm_dma_zone_size - 1;
 	} else
 		arm_dma_limit = 0xffffffff;
+
 	arm_dma_pfn_limit = arm_dma_limit >> PAGE_SHIFT;
+
+	zone_dma_bits = ilog2(arm_dma_limit) + 1;
 #endif
 }
 
@@ -482,7 +488,7 @@ static void __init free_highpages(void)
  */
 void __init mem_init(void)
 {
-#ifdef CONFIG_ARM_LPAE
+#ifdef CONFIG_SWIOTLB
 	swiotlb_init(1);
 #endif
 
-- 
2.23.0


  parent reply	other threads:[~2019-10-14 18:32 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-14 18:31 [PATCH RFC 0/5] ARM: Raspberry Pi 4 DMA support Nicolas Saenz Julienne
2019-10-14 18:31 ` [PATCH RFC 1/5] dma/direct: turn ARCH_ZONE_DMA_BITS into a variable Nicolas Saenz Julienne
2019-10-30 21:49   ` Christoph Hellwig
2019-10-31 10:30     ` Nicolas Saenz Julienne
2019-10-31 13:38       ` Christoph Hellwig
2019-10-31 17:26         ` Nicolas Saenz Julienne
2019-10-14 18:31 ` [PATCH RFC 2/5] ARM: introduce arm_dma_direct Nicolas Saenz Julienne
2019-10-15 10:04   ` Christoph Hellwig
2019-10-14 18:31 ` Nicolas Saenz Julienne [this message]
2019-10-14 18:31 ` [PATCH RFC 4/5] dma/direct: check for overflows in ARM's dma_capable() Nicolas Saenz Julienne
2019-10-15 10:23   ` Christoph Hellwig
2019-10-15 13:07     ` Nicolas Saenz Julienne
2019-10-14 18:31 ` [PATCH RFC 5/5] ARM: bcm2711: use dma-direct Nicolas Saenz Julienne
2019-10-14 20:59 ` [PATCH RFC 0/5] ARM: Raspberry Pi 4 DMA support Catalin Marinas
2019-10-15  7:48   ` Nicolas Saenz Julienne
2019-10-15 17:46     ` Catalin Marinas

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