950-0707-ARM-bcm283x-Enable-DMA-support-for-SPI-controller.patch

From cce15c51f1afbb1aa9d5f7779c9f7c0a17b39701 Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@wunner.de>
Date: Thu, 9 May 2019 19:03:00 +0200
Subject: [PATCH] ARM: bcm283x: Enable DMA support for SPI controller
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Without this, the driver for the BCM2835 SPI controller uses interrupt
mode instead of DMA mode, incurring a significant performance penalty.
The Foundation's device tree has had these attributes for years, but for
some reason they were never upstreamed.

They were originally contributed by Noralf Trønnes and Martin Sperl:
https://github.com/raspberrypi/linux/commit/25f3e064afc8
https://github.com/raspberrypi/linux/commit/e0edb52b47e6

The DREQ numbers 6 and 7 are documented in section 4.2.1.3 of:
https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf

Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Cc: Martin Sperl <kernel@martin.sperl.org>
Cc: Noralf Trønnes <noralf@tronnes.org>
---
 arch/arm/boot/dts/bcm283x.dtsi | 2 ++
 1 file changed, 2 insertions(+)

--- a/arch/arm/boot/dts/bcm283x.dtsi
+++ b/arch/arm/boot/dts/bcm283x.dtsi
@@ -403,6 +403,8 @@
 			reg = <0x7e204000 0x200>;
 			interrupts = <2 22>;
 			clocks = <&clocks BCM2835_CLOCK_VPU>;
+			dmas = <&dma 6>, <&dma 7>;
+			dma-names = "tx", "rx";
 			#address-cells = <1>;
 			#size-cells = <0>;
 			status = "disabled";