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 <[email protected]>
raspberrypi · May 1, 2020 · f72d18f · f72d18f
1 parent 28fd8b5
commit f72d18f
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diff --git 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>;
 	};
 };
diff --git 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")