I am using L4T version: R36 (release), REVISION: 3.0. When using the SPI controller, I noticed a certain delay between each transfer. I am using the default spidev driver provided by the kernel, and the test program is also the default one in the kernel, located at tools/spi/spidev_test.c. The test command is as follows:
bash
sudo ./spidev_test -D /dev/spidev1.0 -s 12000000 -S 32 -I 1000
I added GPIO toggle operations at the entry and exit of the tegra_spi_transfer_one_message function in the file drivers/spi/spi-tegra114.c. I found that this function takes around 52us to execute, while the actual data transfer only took 22us. So, where is the remaining 30us spent?
