imx-i2c frequency scaling issue imx6ull + edt-ft5x06

Michael Nazzareno Trimarchi michael at
Wed Dec 2 05:24:51 EST 2020

Hi all

I'm trying to find the best way to fix a problem connected with the
touch screen controller on i2c imx6ull bus. Now
according to what I understand sdma can not be connected to the i2c
peripheral so it works in pio mode and that's fine.
During the frequency scaling a new clock register is computed but can
not be applied to the register until the next start as
reported by the datasheet. The problem here is that if the i2c
transaction is around PRE_CHANGE and POST_CHANGE of the
rate touchscreen starts to fail and swipe can not be performed until
we get a pen up event (edf- has crc error). Is there any suggestion
based on your experience? In the oscilloscope I can see this effect too


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