openwrt/target/linux/bcm27xx/patches-5.4/950-0692-ARM-dts-bcm2711-Allow-40-bit-DMA-for-SPI.patch

From 0dcafa8ab800d1f534bb0cb51cd02a082cf34be6 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Thu, 30 Apr 2020 12:43:05 +0100
Subject: [PATCH] ARM: dts: bcm2711: Allow 40-bit DMA for SPI

Add the spi_dma4 DT parameter to enable use of the 40-bit DMA channels
to drive SPI. Note that there are only 3-4 40-bit channels available,
and using this parameter claims 2 of them.

Usage: dtparam=spi_dma4

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
 arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 2 ++
 arch/arm/boot/dts/overlays/README     | 4 ++++
 2 files changed, 6 insertions(+)

--- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
+++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
@@ -554,5 +554,7 @@
 		eth_led0 = <&phy1>,"led-modes:0";
 		eth_led1 = <&phy1>,"led-modes:4";
 
+		spi_dma4 = <&spi0>, "dmas:0=", <&dma40>,
+			   <&spi0>, "dmas:8=", <&dma40>;
 	};
 };
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -159,6 +159,10 @@ Params:
         spi                     Set to "on" to enable the spi interfaces
                                 (default "off")
 
+        spi_dma4                Use to enable 40-bit DMA on spi interfaces
+                                (the assigned value doesn't matter)
+                                (2711 only)
+
         random                  Set to "on" to enable the hardware random
                                 number generator (default "on")