# How to Enable SPI Slave mode for TX2i under L4T R28.2??? **URL:** \ **Category:** Jetson TX2\ **Created:** [September 2, 2019, 9:28am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994 "2019-09-02T09:28:16Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Linuxgogo](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@Linuxgogo](https://forums.developer.nvidia.com/u/Linuxgogo)\ **Post date:** [September 2, 2019, 9:28am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994/1 "2019-09-02T09:28:16Z")
I have successfully enabled SPI by[url] [https://elinux.org/Jetson/TX2\_SPI[/url].Then,I](https://elinux.org/Jetson/TX2_SPI%5B/url%5D.Then,I) want Enable the SPI to Slave mode,but I don’t know how to do? I have the following questions for enabling SPI slave: (1). What DTB changes are needed to configure a SPI bus as slave instead of master? (2). How should I use SPI to communicate with two TX2I to test that SPI can be used normally? Thanks in advanced for any input. ---
**Author:** ![ShaneCCC](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/shaneccc/32/14043_2.png) [@ShaneCCC](https://forums.developer.nvidia.com/u/ShaneCCC)\ **Post date:** [September 3, 2019, 2:02am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994/2 "2019-09-03T02:02:41Z")
Have a check below document [url][https://github.com/arter97/android\_kernel\_nvidia\_shieldtablet/blob/master/Documentation/devicetree/bindings/spi/nvidia%2Cspi-slave-tegra124.txt[/url]](https://github.com/arter97/android_kernel_nvidia_shieldtablet/blob/master/Documentation/devicetree/bindings/spi/nvidia%2Cspi-slave-tegra124.txt%5B/url%5D) ---
**Author:** ![Linuxgogo](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@Linuxgogo](https://forums.developer.nvidia.com/u/Linuxgogo)\ **Post date:** [September 3, 2019, 9:39am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994/3 "2019-09-03T09:39:02Z")
HI ShaneCCC,thank you , How do I know if SPI\_SLAVE mode is successfully turned on? ---
**Author:** ![ShaneCCC](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/shaneccc/32/14043_2.png) [@ShaneCCC](https://forums.developer.nvidia.com/u/ShaneCCC)\ **Post date:** [September 4, 2019, 2:58am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994/4 "2019-09-04T02:58:13Z")
You may have log from the SPI host driver first and then connect the device to try it. ---
**Author:** ![Linuxgogo](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@Linuxgogo](https://forums.developer.nvidia.com/u/Linuxgogo)\ **Post date:** [September 4, 2019, 3:44am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994/5 "2019-09-04T03:44:16Z")
thank you @ShaneCCC,but it not work, this is my dts spi@3240000 { reg = \<0x0 0x3240000 0x0 0x10000\>; dmas = \<0x18 0x12 0x18 0x12\>; interrupts = \<0x0 0x27 0x4\>; compatible = “nvidia,tegra186-spi-slave”; clock-names = “spi”, “pll\_p”, “clk\_m”; reset-names = “spi”; clocks = \<0xd 0x4a 0xd 0x10d 0xd 0x261\>; nvidia,dma-request-selector = \<0x18 0x12\>; resets = \<0xd 0x2b\>; status = “okay”; #address-cells = \<0x1\>; phandle = \<0x7d\>; nvidia,clk-parents = “pll\_p”, “clk\_m”; #stream-id-cells = \<0x1\>; #size-cells = \<0x0\>; dma-names = “rx”, “tx”; linux,phandle = \<0x7d\>; ``` spi@0 { reg = <0x0>; compatible = "spidev"; spi-max-frequency = <0x1312d00>; }; }; ``` this is Boot log nvidia@tegra-ubuntu:/usr/src/kernel/kernel-4.4/Documentation/devicetree/bindings/spi$ dmesg | grep spi [0.278381] iommu: Adding device 3210000.spi to group 6 [0.278778] iommu: Adding device c260000.spi to group 7 [0.279144] iommu: Adding device 3240000.spi to group 8 [2.680130] spi-tegra114 3210000.spi: Static pin configuration used [2.680634] spi-tegra114 c260000.spi: Static pin configuration used [2.681485] spi-tegra124-slave 3240000.spi: Probe Deferred, ret -517 [3.969343] spi-tegra114 3210000.spi: Static pin configuration used [3.970130] spi-tegra114 c260000.spi: Static pin configuration used this is error nvidia@tegra-ubuntu:~$ gcc spidev\_test.c nvidia@tegra-ubuntu:~$ sudo ./a.out -D /dev/spidev3.0 -4 -v [sudo] password for nvidia: spi mode: 0x0 bits per word: 8 max speed: 500000 Hz (500 KHz) can’t send spi message: Invalid argument Aborted (core dumped) Thanks in advanced for any input. ---
**Author:** ![ShaneCCC](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/shaneccc/32/14043_2.png) [@ShaneCCC](https://forums.developer.nvidia.com/u/ShaneCCC)\ **Post date:** [September 4, 2019, 3:52am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994/6 "2019-09-04T03:52:19Z")
Please use tegra124-spi-slave instead of tegra186-spi-slave ---
**Author:** ![Linuxgogo](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@Linuxgogo](https://forums.developer.nvidia.com/u/Linuxgogo)\ **Post date:** [September 4, 2019, 4:04am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994/7 "2019-09-04T04:04:14Z")
Thank you for your reply @ShaneCCC, Unfortunately, it still can’t be used, and the error is the same as the original. ---
**Author:** ![Linuxgogo](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@Linuxgogo](https://forums.developer.nvidia.com/u/Linuxgogo)\ **Post date:** [September 4, 2019, 4:17am UTC](https://forums.developer.nvidia.com/t/how-to-enable-spi-slave-mode-for-tx2i-under-l4t-r28-2/80994/8 "2019-09-04T04:17:45Z")
HI ShaneCCC , [2.681485] spi-tegra124-slave 3240000.spi: Probe Deferred, ret -517 this error is from Init dma parame In spi-tegra124.slave.c,Is this a problem there?