@Takuma Fujiwara

Hi Fei,

Please reference this appnote: https://www.ti.com/lit/an/sprad26/sprad26.pdf?ts=1732143558409&ref_url=https%253A%252F%252Fwww.google.com%252F

Specifically, the following sections will be a good read:

• section "3.3 Exercise SPI From User Space on TI J7/TDA4x Using Standard Linux spidev_test Tool", because it looks like this is what you are seeing currently.
• section "4 SPI: Slave Mode Enabling and Validation on Linux", because this is most likely what is missing.

Regards,

Takuma

thankyou, I will read this pdf again, but we work on SPI master mode,  RX means reading data via MISO

hello,

although we just want master mode on TDA4VM,

slave mode is also needed to enable ?

linux sdk: ti-processor-sdk-linux-adas-j721e-evm-10_00_00_08, use this script: ./spidev_test -v -D /dev/spidev1.0 -p "HELLOWORLD" to watch SPI RX,we try TX and RX short connected and RX pulled up, but RX still zero, the problem maybe comes with the SDK

Hi Fei,

pls see below reply from Takuma.

(10) TDA4VM-Q1: J721e - Processors forum - Processors - TI E2E support forums

Do you work with Sijia? Mainly trying to see if I can assume if this is on the same SDK and system as described by Sijia.

In any case, the spidev_test is an application from upstream Linux. So the source code is available here: https://github.com/torvalds/linux/blob/master/tools/spi/spidev_test.c

Looking through the source code, it seems there is a "bpw" bits per word argument you could give to spidev_test.

BR,

Biao

HI ,

yes we are one team and focus on the same spi problem，we try 8 or 16bits per word but RX still zero,spidev_test has defalut bpw 8 bits

BR

Hi Fei,

It looks like software-wise, the 8 bits per word vs 16 bits per word was successfully changed based on your screenshot.

On the other hand, for RX not showing any data, I have not tested out a loopback on a single SPI interface. Only tested the case where there is a separate SPI slave. In the appnote, they configure a different SPI interface as slave to do some communication, but could you try setting slave mode on a different SPI interface to try the same?

Regards,

Takuma 

HI Takuma,

Initially, TDA4 is host and connected the slave mmwave chip, and the rx was 0, so we left out the business code and used the standard Linux spitest test to test that the rx was 0.

Hi Takuma,

i add debug print in driver, and found rx reg is 

the value read from RX REG is always 0

maybe you can also use the RX(D0) pin high level without loopback.

done by set to use spi3 standalone

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1104313/tda4vm-tda4-how-to-write-memory-io-in-linux-kernel-driver