On Thu, 22 Sep 2016 23:52:52 +0200
Danny Milosavljevic <dan...@scratchpost.org> wrote:

> Hello,
> 
> when using SPI on Allwinner A20 with CPOL=1 and CPHA=1 with Linux 4.8.0-rc6 
> Psychotic Stoned Sheep I see a weird dip in the beginning (which also 
> confuses the slave) on the SCLK line right when SSEL goes low - see 
> attachment.
> 
> The lines are, starting from the top, SCLK MOSI MISO SSEL.
> 
> I'm using spidev.
> 
> Did anyone see this problem before?

Hi,

I'm not sure, but something like this might be somehow related:
    https://patchwork.kernel.org/patch/7960811/

As a random thing to check, I would also advise to verify the
pull-up/pull-down settings for the SCLK pin.

And maybe as another test, change the driver to automatically
drive the SSEL pin instead of doing this manually.

Also try to contact the author of the SPI driver via the
mainline kernel mailing list.

-- 
Best regards,
Siarhei Siamashka

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