Original question:
For enabling SPI on J721E/TDA4VM, I have seen the following:
I have seen this FAQ, https://e2e.ti.com/support/processors-group/processors/f/processors-forum/947437/faq-ccs-tda4vm-how-to-use-spi-spi_dev-on-tda4-j721e
And I have also seen this application note, https://www.ti.com/lit/an/sprad26/sprad26.pdf
However, when I apply the patch to device tree for SK-TDA4VM, I receive errors at compile and/or runtime.
How can I enable spidev for SK-TDA4VM?
Although the FAQ and app note does not call this out, these were made using the J721E EVM board instead of the SK board. Therefore, pins that are unused by peripherals have changed due to differences in the board design.
From the schematics (https://www.ti.com/lit/zip/sprr438) for the SK-TDA4VM board, SPI5 is pinned out to the 40-pin header:
SDK 8.x
Below are two files. One is a prebuilt dtb file that can be dropped into rootfs partition's boot folder which should work with default Edge AI SDK image's Linux kernel for SK-TDA4VM, and the other is a patch for generating the dtb. After the patch is applied to the Linux source code in "<PSDK Linux installation>/board-support/linux-*", it can be built following the SDK userguide: https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-jacinto7/08_06_01_02/exports/docs/linux/Overview_Top_Level_Makefile.html. These have been created with SDK 8.6 version, so the prebuilt dtb will only work with 8.6 version of SDK.
0001-SK-TDA4VM-Processor-SDK-Linux-8.6.1.2-patch-for-SPI5.patch
Spidev should come up under /dev folder, and get enumerated as spidev8.0 (the number can vary but it should be using spi5 nonetheless). Using spidev_test as mentioned in this appnote should make things be transmitted: https://www.ti.com/lit/an/sprad26/sprad26.pdf
SDK 9.x
For 9.0 and 9.1 SDK, in addition to the patch for 8.x, apply below patch to make the spidev driver get probed:
0001-adding-linux-spidev-device-tree-compatibility-into-s.patch
Regards,
Takuma
