NX SPI timming tunnig

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
1

Hi expert,

where can i find to change spi timming on NX module?

Best regards.
Peter

3

Not sure exactly what timing you want.
Have a reference to below to check if any device tree configure as your expect.

https://android.googlesource.com/kernel/tegra.git/+/2ce2576c4a8fb4942cc3c75d4f81a32138a98f0e/Documentation/devicetree/bindings/spi/nvidia,spi-tegra114.txt

4

Hi Shane,

We want to tune the clock data delay. I just check the link:
nvidia,enable-hw-based-cs;
nvidia,cs-setup-clk-count = <10>;
nvidia,cs-hold-clk-count = <10>;
nvidia,rx-clk-tap-delay = <0>;
nvidia,tx-clk-tap-delay = <16>;

It seems it adjusts the delay, where can I find the registers in NX manual.

Best regards
Peter

5

Download the TRM from download center.

6

Hello Shane,
In TRM, we found TX and RX delay tunning. Where can we find the physical meaning of these delay in timing chart?

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Best regards
Peter

7

Please have check the kernel driver …/kernel/kernel-4.9/drivers/spi/spi-tegra114.c

8

Thank you, Shane.

I saw the default tx/rx delay (0/10), but i can’t judge it’s reasonable or not.

#define SPI_DMA_TIMEOUT (msecs_to_jiffies(10000))
#define DEFAULT_SPI_DMA_BUF_LEN (161024)
#define TX_FIFO_EMPTY_COUNT_MAX SPI_TX_FIFO_EMPTY_COUNT(0x40)
#define RX_FIFO_FULL_COUNT_ZERO SPI_RX_FIFO_FULL_COUNT(0)
#define MAX_HOLD_CYCLES 16
#define SPI_DEFAULT_SPEED 25000000
#define SPI_SPEED_TAP_DELAY_MARGIN 35000000
#define SPI_POLL_TIMEOUT 10000
#define SPI_DEFAULT_RX_TAP_DELAY 10
#define SPI_DEFAULT_TX_TAP_DELAY 0
#define SPI_FIFO_FLUSH_MAX_DELAY 2000
#define AUTOSUSPEND_TIMEOUT 300 / in millisec */

Best regards
Peter