Thread (5 messages) 5 messages, 3 authors, 2026-02-03

Re: [PATCH v3 1/2] arm64: dts: imx95: Reserve eDMA channels 0-1 for V2X

From: Laurentiu Mihalcea <hidden>
Date: 2026-02-03 10:17:03
Also in: imx, linux-arm-kernel, lkml

On 2/1/2026 7:22 PM, Peng Fan wrote:
Hi Joy,

Sorry to jump in at V3.

On Fri, Jan 30, 2026 at 05:36:27PM +0800, Joy Zou wrote:
quoted
Reserve eDMA channels 0 and 1 on the AXI eDMA controller for exclusive
use by V2X (Vehicle-to-Everything) fast hash operations.

Reviewed-by: Laurentiu Mihalcea <redacted>
Tested-by: Laurentiu Mihalcea <redacted>
Signed-off-by: Joy Zou <redacted>
---
arch/arm64/boot/dts/freescale/imx95.dtsi | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm64/boot/dts/freescale/imx95.dtsi b/arch/arm64/boot/dts/freescale/imx95.dtsi
index 55e2da094c889fc7c1096d0e36f31ae118d2a982..9ac82da2ff440e08ae8378d7ff830a568d50a354 100644
--- a/arch/arm64/boot/dts/freescale/imx95.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx95.dtsi
@@ -631,6 +631,8 @@ edma2: dma-controller@42000000 {
				reg = <0x42000000 0x210000>;
				#dma-cells = <3>;
				dma-channels = <64>;
+				/* channels 0 and 1 reserved for V2X fast hash */
+				dma-channel-mask = <0x3>;
This is wrong. Per dt-binding,
dma-channel-mask means Bitmask of available DMA channels in ascending order,
The usage in this patch does not match the dt-binding.

Ah, good catch. It would seem like our EDMA driver reverses the meaning of the "dma-channel-mask"

bits (i.e. bit x set means channel x reserved instead of channel x available).


Now, I wonder how we should be proceeding with this. According to the DT binding, our devicetree

configurations are wrong. Since there seem to be only 8 upstream instances in which this property is

being used I guess it wouldn't be so difficult to correct the driver's behavior and then correct the

devicetrees?
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