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

[bighero77]

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.

[pengyong_zhang]

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

[pengyong_zhang]

Hi @bighero77 

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

B.R

[bighero77]

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

thanks.