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43 lines
1.6 KiB
Diff
43 lines
1.6 KiB
Diff
From cce15c51f1afbb1aa9d5f7779c9f7c0a17b39701 Mon Sep 17 00:00:00 2001
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From: Lukas Wunner <lukas@wunner.de>
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Date: Thu, 9 May 2019 19:03:00 +0200
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Subject: [PATCH] ARM: bcm283x: Enable DMA support for SPI controller
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Without this, the driver for the BCM2835 SPI controller uses interrupt
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mode instead of DMA mode, incurring a significant performance penalty.
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The Foundation's device tree has had these attributes for years, but for
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some reason they were never upstreamed.
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They were originally contributed by Noralf Trønnes and Martin Sperl:
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https://github.com/raspberrypi/linux/commit/25f3e064afc8
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https://github.com/raspberrypi/linux/commit/e0edb52b47e6
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The DREQ numbers 6 and 7 are documented in section 4.2.1.3 of:
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https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
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Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
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Signed-off-by: Lukas Wunner <lukas@wunner.de>
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Reviewed-by: Eric Anholt <eric@anholt.net>
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Reviewed-by: Martin Sperl <kernel@martin.sperl.org>
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Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
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Cc: Martin Sperl <kernel@martin.sperl.org>
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Cc: Noralf Trønnes <noralf@tronnes.org>
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---
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arch/arm/boot/dts/bcm283x.dtsi | 2 ++
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1 file changed, 2 insertions(+)
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--- a/arch/arm/boot/dts/bcm283x.dtsi
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+++ b/arch/arm/boot/dts/bcm283x.dtsi
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@@ -403,6 +403,8 @@
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reg = <0x7e204000 0x200>;
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interrupts = <2 22>;
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clocks = <&clocks BCM2835_CLOCK_VPU>;
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+ dmas = <&dma 6>, <&dma 7>;
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+ dma-names = "tx", "rx";
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#address-cells = <1>;
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#size-cells = <0>;
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status = "disabled";
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