[Letux-kernel] Status of JZ4780/CI20 upstream support

Paul Boddie paul at boddie.org.uk
Mon Jul 8 16:12:48 CEST 2019

On Monday 8. July 2019 15.36.27 H. Nikolaus Schaller wrote:
> Hi,
> Linus has released v5.2 and I wonder about the status of
> JZ4780/CI20 upstream support.
> I can boot the CI20 V2a. SD card and Ethernet are working
> and I could forward-port some patches from the old 3.18
> kernel to make the LED0..LED3 gpio-leds work.

As I noted on the Tinkerphones and letux-kernel lists, to get these LEDs 
working in 5.1.x merely required the definition of the device tree nodes and 
the inclusion of various CONFIG_LED settings in the kernel configuration.

It's good that the SD card and Ethernet work because it means that I can 
access my CI20 over the network. And with the activity LEDs working, I can 
tell whether it booted. :-)

> What is missing or not working on my setup:
> * HDMI / DRM / framebuffer
> * USB
> * ov5640 camera
> * WiFi
> * (not tested) Audio
> * Paul reported that only one core seems to be up and running
> So I wonder who else is working on such things and how I (and
> we from the LetuxOS kernel project [1]) can support.

I was going to look at USB today, seeing what it would take to get the JZ4780-
specific host drivers working with a newer kernel than 3.18. The initial 
motivation was to make the main LED responsive since it appears to be 
connected to a pin designated for USB VBUS:


I am imagining that if the USB drivers are actually in place, their activation 
and deactivation will also cause the pin to change value and thereby cause the 
LED to switch off upon shutdown.

> Maybe there have been unsiccessful attempts to get the missing
> features upstream and we would like to learn about.

Maybe we should update the upstreaming page on the eLinux wiki:


I could probably update that, given that I have been updating other things 
related to the CI20 there.

> My personal long-term goal is to get the PVR/SGX working again
> and harmonize that with the code available for OMAP3/4/5 to
> make it easier to work on a single source code version of the
> kernel driver.
> BR and thanks,
> Nikolaus
> [1]: http://projects.goldelico.com/p/gta04-kernel/

I think I could live with non-free PVR/SGX video if it allowed me to retire my 
current desktop machine and use the CI20 instead.


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