1. 前言
想运行spi测试通过连接的spi1和spi3的jetson xavier nx板。 在连接spi1-spi3之前，我连接了spi1的MOSI-MISO (spi3的MOSI-MISO)， 并使用spidev_test.c示例进行了测试，以确认tx rx在spi1和spi3上都可以正常工作。
刚开始调试时有以下几个问题
（1）连接spi1和spi3时，如何设置主模式和从模式? 是否更新pinmux吗?
（2）下面两种方法之间的spi1-spi3如何连接?
a. spi1 MISO <-> spi3 MISO / spi1 MOSI <-> spi3 MOSI / spi1 SCK<-> spi3 SCK / spi1 CS0 <-> spi CS0 b. spi1 MISO <-> spi3 MOSI / spi1 MOSI <-> spi3 MISO / spi1 SCK<-> spi3 SCK / spi1 CS0 <-> spi CS0(3)如何做rx在spi 从模式? 当数据进入时是否出现中断? 查看spi示例(spidev_test.c)， ioctl(fd, SPI_IOC_MESSAGE(1)， &tr)用于检查tx和rx。 这是检查rx的唯一方法吗?
2. 参考方法（1）配置如下
将tegra124-spi-slave添加到设备树中。 使用两个xavier，一个用于master，另一个用于slave
这是master dts
spi0: spi@3210000 { compatible = “nvidia,tegra186-spi”; reg = <0x0 0x03210000 0x0 0x10000>; interrupts = <0 36 0x04>; #address-cells = <1>; #size-cells = <0>; iommus = <&smmu TEGRA_SID_GPCDMA_0>; dma-coherent; dmas = <&gpcdma 15>, <&gpcdma 15>; dma-names = “rx”, “tx”; nvidia,dma-request-selector = <&gpcdma 15>; spi-max-frequency = <65000000>; nvidia,clk-parents = “pll_p”, “clk_m”; clocks = <&bpmp_clks TEGRA194_CLK_SPI1>, <&bpmp_clks TEGRA194_CLK_PLLP_OUT0>, <&bpmp_clks TEGRA194_CLK_CLK_M>; clock-names = “spi”, “pll_p”, “clk_m”; resets = <&bpmp_resets TEGRA194_RESET_SPI1>; reset-names = “spi”; status = “okay”; nvidia,clock-always-on; spi@0 { compatible = “spidev”; reg = <0>; spi-max-frequency = <65000000>; status = “okay”; }; };<
这是slave dts
spi0: spi@3210000 { compatible = “nvidia,tegra124-spi-slave”; reg = <0x0 0x03210000 0x0 0x10000>; interrupts = <0 36 0x04>; #address-cells = <1>; #size-cells = <0>; iommus = <&smmu TEGRA_SID_GPCDMA_0>; dma-coherent; dmas = <&gpcdma 15>, <&gpcdma 15>; dma-names = “rx”, “tx”; nvidia,dma-request-selector = <&gpcdma 15>; spi-max-frequency = <65000000>; nvidia,clk-parents = “pll_p”, “clk_m”; clocks = <&bpmp_clks TEGRA194_CLK_SPI1>, <&bpmp_clks TEGRA194_CLK_PLLP_OUT0>, <&bpmp_clks TEGRA194_CLK_CLK_M>; clock-names = “spi”, “pll_p”, “clk_m”; resets = <&bpmp_resets TEGRA194_RESET_SPI1>; reset-names = “spi”; status = “okay”; nvidia,clock-always-on; spi@0 { compatible = “spidev”; reg = <0>; spi-max-frequency = <65000000>; nvidia,slave-ready-gpio=<&tegra_main_gpio TEGRA194_MAIN_GPIO(T, 3) 0>; nvidia,enable-hw-based-cs; status = “okay”; }; };<
（2）测试方法
打开SSH终端，首先用下面的命令启动spi从属
．/spidev_test -D /dev/spidev0.0 -s 150000 -n100 -g30 -p4 -z在另一个终端中，使用以下命令启动spi master
./spidev_test -D /dev/spidev3.1 -s 150000 -n100 -g30 -p4 -z 3. 调试记录继续以下方式修改dts。 （1）执行/opt/nvidia/jetson-io/jetson-io.py命令，激活spi1、spi3
（2）
sudo dtc -I dts -O dtb -o ~/user-custom.dts /boot/tegra194-p3668-all-p3509-0000-user-custom.dtb（3）修改user-custom.dts
spi@3210000 { compatible = “nvidia,tegra186-spi”; reg = <0x0 0x3210000 0x0 0x10000>; interrupts = <0x0 0x24 0x4>; #address-cells = <0x1>; #size-cells = <0x0>; iommus = <0x2 0x20>; dma-coherent; dmas = <0x19 0xf 0x19 0xf>; dma-names = “rx”, “tx”; spi-max-frequency = <0x3dfd240>; nvidia,clk-parents = “pll_p”, “clk_m”; clocks = <0x4 0x87 0x4 0x66 0x4 0xe>; clock-names = “spi”, “pll_p”, “clk_m”; resets = <0x5 0x5b>; reset-names = “spi”; status = “okay”; linux,phandle = <0xf2>; phandle = <0xf2>; spi@0 { compatible = “spidev”; reg = <0x0>; spi-max-frequency = <0x2faf080>; controller-data { nvidia,enable-hw-based-cs; nvidia,rx-clk-tap-delay = <0x10>; nvidia,tx-clk-tap-delay = <0x0>; }; }; spi@1 { compatible = “spidev”; reg = <0x1>; spi-max-frequency = <0x2faf080>; controller-data { nvidia,enable-hw-based-cs; nvidia,rx-clk-tap-delay = <0x10>; nvidia,tx-clk-tap-delay = <0x0>; }; }; }; spi@3230000 { compatible = “nvidia,tegra186-spi-slave”; reg = <0x0 0x3230000 0x0 0x10000>; interrupts = <0x0 0x26 0x4>; #address-cells = <0x1>; #size-cells = <0x0>; iommus = <0x2 0x20>; dma-coherent; dmas = <0x19 0x11 0x19 0x11>; dma-names = “rx”, “tx”; spi-max-frequency = <0x3dfd240>; nvidia,clk-parents = “pll_p”, “clk_m”; clocks = <0x4 0x89 0x4 0x66 0x4 0xe>; clock-names = “spi”, “pll_p”, “clk_m”; resets = <0x5 0x5d>; reset-names = “spi”; status = “okay”; linux,phandle = <0xf4>; phandle = <0xf4>; spi@0 { compatible = “spidev”; reg = <0x0>; spi-max-frequency = <0x2faf080>; controller-data { nvidia,enable-hw-based-cs; nvidia,rx-clk-tap-delay = <0x10>; nvidia,tx-clk-tap-delay = <0x0>; }; }; spi@1 { compatible = “spidev”; reg = <0x1>; spi-max-frequency = <0x2faf080>; controller-data { nvidia,enable-hw-based-cs; nvidia,rx-clk-tap-delay = <0x10>; nvidia,tx-clk-tap-delay = <0x0>; }; }; };<
（4）
sudo dtc -I dts -O dtb -o /boot/tegra194-p3668-all-p3509-0000-user-custom.dtb ~/user-custom.dts（5）reboot
通过以这种方式修改dts, spi1(master, spidev0.0)、spi3(slave, spidev2.0)被连接并按如下方式执行。
/spidev_test -D /dev/spidev2.0 -s 150000 -n10000 -g30 -p4 -z ./spidev_test -D /dev/spidev0.0 -s 150000 -n10000 -g30 -p4 -z结果如图所示
当我在从模式运行它，一个传输错误发生和主测试失败。
(5)让devmem2读取那些REG来确认设置。
使用了devmem2来临时更改寄存器值。
检查dmesg时，出现以下错误。
[ 280.340212] spi-tegra124-slave 3230000.spi: Tx is not supported in mode 0 [ 280.340215] spi-tegra124-slave 3230000.spi: spi can not start transfer, err -22 [ 280.340301] spi_master spi2: failed to transfer one message from queue
