Asus PN50 CEC

Asus PN50 CEC

[Timo Ketola]

Hi all,

I'm not sure  weather this is the right place to ask but one has to 
start somewhere. Here we go:

I bought an Asus PN50 mini PC (Ryzen 3 4300U). It should have HDMI-CEC 
and there indeed are some related settings in the BIOS. But there seems 
to be no support for it in Linux and I can't find any hints how it might 
have been implemented on the hardware side.

Any ideas what to do now?

--

Timo

Re: Asus PN50 CEC

[Hans Verkuil]

On 07/09/2020 21:49, Timo Ketola wrote:
> Hi all,
> 
> I'm not sure  weather this is the right place to ask but one has to start somewhere. Here we go:
> 
> I bought an Asus PN50 mini PC (Ryzen 3 4300U). It should have HDMI-CEC and there indeed are some related settings in the BIOS. But there seems to be no support for it in Linux and I can't find any
> hints how it might have been implemented on the hardware side.
> 
> Any ideas what to do now?

I suspect that this is a BIOS-only implementation that just does the bare minimum
for wake up and standby (if enabled).

Similar to what Intel did on some of their NUCs.

Not very useful since it can't be accessed from the OS.

That said, I can't really find any good information on it since I could only
find a Quick Start manual that had no information on this.

Regards,

	Hans

Re: Asus PN50 CEC

[Timo Ketola]

On 8.9.2020 10.57, Hans Verkuil wrote:
> I suspect that this is a BIOS-only implementation that just does the bare minimum
> for wake up and standby (if enabled).

What does it mean? Is it just that BIOS does not report about it to the 
OS? If it was implemented with GPIOs, shouldn't it still be possible to 
write a driver for it - in theory - if we somehow were able to find out 
the GPIOs?

Unfortunately, I don't know too much about modern PCs at this level.

Thanks for looking at this!

--

Timo

Re: Asus PN50 CEC

[Hans Verkuil]

On 08/09/2020 10:13, Timo Ketola wrote:
> On 8.9.2020 10.57, Hans Verkuil wrote:
>> I suspect that this is a BIOS-only implementation that just does the bare minimum
>> for wake up and standby (if enabled).
> 
> What does it mean? Is it just that BIOS does not report about it to the OS? If it was implemented with GPIOs, shouldn't it still be possible to write a driver for it - in theory - if we somehow were
> able to find out the GPIOs?

Usually CEC is handled by a microcontroller or a specialized CEC chip.
It's rare to see a pure GPIO implementation.

So it is typically not possible to get access to it if it is all handled in
the BIOS. At least, I've never seen it.

I also suspect that what they call 'CEC' is a really cut-down implementation,
just enough to receive/transmit wake-up and standby messages.

Sadly, without any documentation there isn't anything that can be done about this.

If you want to support CEC under linux, then go with a Pulse-Eight USB CEC adapter:
this is fully supported by linux.

Regards,

	Hans

> 
> Unfortunately, I don't know too much about modern PCs at this level.
> 
> Thanks for looking at this!
> 
> -- 
> 
> Timo