From 9859a029c89eb4aa584fa6cadfcad94d6ba25a3c Mon Sep 17 00:00:00 2001 From: Stefan Wahren Date: Thu, 11 Apr 2024 12:05:48 +0200 Subject: [PATCH] ARM: dts: imx6ull-tarragon-common: Disable DMA for both SPI Comparing linux-imx 4.9.11 and this branch shows a significant performance gap on the SPI. The vendor branch has DMA disabled, so SPI operates just in PIO mode. A possible reason for this is that the SDMA ROM firmware has issues. So instead of enabling the SDMA driver with all these consequences, just disable DMA as in the vendor branch. Parameter: Poll limit = 30 usec (default) Before Mode: Poll + DMA mains PLC throughput: ~ 2.69 Mbits/sec mains PLC latency: ~ 5.2 msec After Mode: Poll + PIO mains PLC throughput: ~ 5.00 Mbits/sec mains PLC latency: ~ 4.5 msec Signed-off-by: Stefan Wahren --- arch/arm/boot/dts/imx6ull-tarragon-common.dtsi | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm/boot/dts/imx6ull-tarragon-common.dtsi b/arch/arm/boot/dts/imx6ull-tarragon-common.dtsi index 5248a058230c86..fd88923e355a56 100644 --- a/arch/arm/boot/dts/imx6ull-tarragon-common.dtsi +++ b/arch/arm/boot/dts/imx6ull-tarragon-common.dtsi @@ -97,6 +97,8 @@ cs-gpios = <&gpio1 29 GPIO_ACTIVE_HIGH &gpio3 2 GPIO_ACTIVE_HIGH &gpio3 4 GPIO_ACTIVE_HIGH>; + /delete-property/dmas; + /delete-property/dma-names; }; &ecspi4 { @@ -106,6 +108,8 @@ pinctrl-0 = <&pinctrl_ecspi4>; num-cs = <1>; cs-gpios = <&gpio2 15 GPIO_ACTIVE_HIGH>; + /delete-property/dmas; + /delete-property/dma-names; }; &fec1 {