I have to configure Colibri MX6QDL_PAD_GPIO_19__GPIO4_IO05 control signals as CLOCK.
Note that the macro name is constructed as __.
Which node can I use? Should I and can I create a new node?
I would delete the MX6QDL_PAD_GPIO_19__GPIO4_IO05 from the pinctrl_weim_gpio_3 and create an additional pinctrl group with only the GPIO19 ball muxed for CLK01.
Then, as you don’t really want to tie it to a driver I would add that addtional pinctrl group to the pinctrl-0 property of iomuxc.
That should do the trick to output CLKO1.
Other question how do I set the clock frequency?
Note that the SGTL5000 audio codec on the module uses CLKO1, so by changing the frequency funny things will happen.
The 24MHz used for the codec are hardcoded here. Please refer to the i.MX6DL/S reference manual on what configuration option you have on CLKO1.
You might be able to change the clock in the device tree. E.g. have a look here.