TK1 spi_readl/spi_writel duration

Autonomous Machines Jetson & Embedded Systems Jetson TK1
1

Hi,

we have a speed problem with the SPI controller in the K1.
We attached an MCP2515 and added some profiling via gpio-pins to detect that the tegra_spi_readl and tegra_spi_writel in spi-tegra114.c consumes most of the time. Each read/write to the spi controller has a duration of about 1.5us. We expected something less that 100ns per access.

Is there someone who has the same experience and knows how to decrease the access time to something on the APB, where the SPI controllers reside?
Does someone know how to check the clock speed, of the APB and its slaves in Linux? Maybe there is some entry in the /sys filesystem.

There are a lot other who had a speed isue with an MCP2515 attached to the SPI controller of the K1.

Thanks a lot
Michael

2

Hello, Michael:
SPI access time is determined by both APB and SPI clock.
You can try to increase them and it may have a little improvement.

(check apb.sclk in sys FS.)

br
ChenJian