topic Re: imx6ull ecspi CS would not drop at constant pattern. sometimes one byte.sometimes one burst. in i.MX Processors

imx6ull ecspi CS would not drop at constant pattern. sometimes one byte.sometimes one burst.

bighero77 — Sun, 15 Jun 2025 04:38:48 GMT

my board is imx6ull. linux is linux4.1.15.

about one month ago. the waveform of CS is like this:
drop to low level during the whole burst (spi.message.length = 240). only 240byte data is transfered, the cs rise.

but, after one month. the module driver is not changed.
I find the cs would not transfer one burst (just one byte) and then it rise to high level.

both waveform are captured by spi.message.length = 240. every test, I would transfer 240 byte as one burst.

I really donnot know what register parameters would cause this difference.

would you please tell me what would control the cs drop pattern?

thanks a lot.

Re: imx6ull ecspi CS would not drop at constant pattern. sometimes one byte.sometimes one burst.

pengyong_zhang — Tue, 17 Jun 2025 05:19:33 GMT

Hi @bighero77

Did you change the SPI CS PIN at this two different Scenario?

B.R

Re: imx6ull ecspi CS would not drop at constant pattern. sometimes one byte.sometimes one burst.

bighero77 — Wed, 18 Jun 2025 14:12:29 GMT

absolutely , I did not change anything.
would you please give one standard setting?
both in dts and module driver code?

thanks.

Re: imx6ull ecspi CS would not drop at constant pattern. sometimes one byte.sometimes one burst.

pengyong_zhang — Thu, 19 Jun 2025 06:45:47 GMT

Hi @bighero77

Actually, when you use the SPI native PIN for CS signal line will like below picture:

When you use the GPIO for SPI cs pin, The cs pin signal line like this picture:

But it very strange you did nothing change, just one month later. Please double check if anyone change your dts file. Also please share me your dts file.

B.R