Compatibility with "HDMI CEC framework" support in mainline Linux 4.8 kernel and later? #67

Hedda · 2015-03-24T10:19:13Z

Update! Linux 4.8 release finally include this HDMI-CEC framework in the mainline kernel.

http://www.phoronix.com/scan.php?page=news_item&px=HDMI-CEC-Linux-4.8

Details on the framework in this PDF:

http://events.linuxfoundation.org/sites/events/files/slides/cec-wide_1.pdf

HDMI CEC Framework project was revived for the Linux Kernel, read some history here:

http://lists.freedesktop.org/archives/dri-devel/2015-March/079678.html

http://www.phoronix.com/scan.php?page=news_item&px=HDMI-CEC-Framework-Linux

http://www.phoronix.com/scan.php?page=news_item&px=MTIwMTk

http://lists.freedesktop.org/archives/dri-devel/2012-October/028716.html

Question is if libCEC can be supported through this framework too? See:

https://hverkuil.home.xs4all.nl/cec.html#cec-api

This new CEC API uses a CEC bus with CEC clients.

Guess this means that LibCEC could be a CEC client usable via this API?

PS: Looks like this "HDMI CEC framework" is sponsored by Samsung & Cisco.

At least the main developers are "Kamil Debski"[email protected] / Kamil Debski [email protected] and "Hans Verkuil" [email protected] / "Hans Verkuil" [email protected]

opdenkamp · 2015-03-24T10:53:55Z

I've seen the discussion on the kernel thread and I've signed up to the mailing list so I can respond, as soon as someone posts something there. Couldn't find a proper way to comment to it when not signed up last week end, but might have missed it :)

I've taken a look at the implementation, and half of it is good: the promiscuous mode that got added, which will indeed allow interfacing with libCEC if done right. Patches to support it are welcome once it enters the kernel.

The other half, trying to process key presses directly in the kernel, not so much:

it simply does not work with half the TVs on the planet because of how those implemented CEC. Simple example: some common brand requires you to respond with their vendor id or refuse to interoperate.
doing some way to initialise things in the kernel and then doing something similar in userspace will confuse certain brands of TVs. Another simple example: using a different OSD name or logical address will make two devices show up in the list of CEC devices on another common brand, and only one of them will work, confusing users
In my opinion, it just does not belong in the kernel, as there's no good reason to do it there when you can do it better in userspace. Like through libCEC which then sends back keys through udev, as suggested by Reference library and API/ABI for interfacing with uinput (and Python) #60 . Kernel support for CEC is just bloat that won't work anyway, as pointed out in the above points.

So, in short, "promiscuous mode" as they call it, is good, if it only does the following:

allocate one or more logical addresses, and ack CEC traffic sent to those logical addresses
receive CEC traffic and forward it to userspace
transmit CEC traffic initiated by userspace

This is the same as the implementations for the Raspberry Pi, TDA995x and Exynos (the current implementation) do.

All the rest should not be done in the kernel.

And if someone who's subscribed to the linux-media mailing list (@anssih or @FernetMenta perhaps?) could post a response to http://lists.freedesktop.org/archives/dri-devel/2015-March/079696.html with this, or tell me how to respond there when I wasn't signed up before the message was posted, then that would be great.

Hedda · 2015-03-25T11:32:43Z

@opdenkamp Maybe just mail the main two developers directly with your feedback?

"Kamil Debski" [email protected]

"Hans Verkuil" [email protected]

Like it that multiple applications can send CEC commands to the same API/client.

Hedda · 2015-07-09T12:04:39Z

FYI, "Hans Verkuil" [email protected] is now on his seventh revision of this patch series

https://patchwork.linuxtv.org/patch/30412/

Hedda · 2016-04-11T08:32:43Z

FYI, Hans Verkuil is still working on this and is now on his 13th version of this patch series:

https://patchwork.linuxtv.org/project/linux-media/list/?submitter=676&archive=both&state=*

The patch is now also devided into seventeen parts.

gdachs · 2016-04-11T14:02:48Z

I got aware of a new cec driver in an unreleased amlogic kernel for android. I will write an adapter for libcec for any implementation I will get hands on first. As my development environment is OpenELEC/LibreELEC and my current hardware is Wetek Play/Core and Odroid C2, I have to wait till it will show up on them.

Hedda · 2016-04-12T07:20:04Z

You could try contacting the developers, Hans Verkuil (a.k.a. hverkuil), either mail directly to Hans Verkuil [email protected] / [email protected] and Kamil Debski [email protected]/ [email protected] or via linuxtv.org mailing-list.

I understand that as reference hardware he and Kamil Debski [email protected] is at present using Samsung Exynos range of SoCs for testing this CEC framework.

Guess that means ODROID U & X series from Hardkernel, such as the ODROID-XU4 http://www.hardkernel.com/main/products/prdt_info.php?g_code=G143452239825

Not sure if OpenELEC is already supported on ODROID-XU4 or not(?).

gdachs · 2016-04-12T07:31:52Z

If the Exynos driver is the reference, then no activity is necessary as there is already an adapter for Exynos in the libcec.

OpenELEC doesn't support Odroid U & X. As far as I know the OpenELEC team doesn't own one of this devices.

Hedda · 2016-04-12T07:47:38Z

You might want to checkout this v4l2-subdev patch, maybe LibCEC could be implemented through it?

https://patchwork.linuxtv.org/patch/33526/

While Exynos seems to be the reference they still look to be working on other hardware too, see patches:

https://patchwork.linuxtv.org/project/linux-media/list/?submitter=676&archive=both&state=*

There are seperate CEC adapters for Cobalt, Exynos, Vivid, ADV7511, ADV7604, and ADV7842 drivers.

gdachs · 2016-04-12T07:56:19Z

That looks strange, receiving cec messages by ioctl calls? Seems not to have something in common with the old exynos driver.
Anyway, I don't expect that this will cross my way anytime soon.

Hedda · 2016-10-07T11:08:20Z

@opdenkamp FYI: Linux 4.8 release finally include this HDMI-CEC framework in the mainline kernel.

http://www.phoronix.com/scan.php?page=news_item&px=HDMI-CEC-Linux-4.8

Details on the framework in this PDF:

http://events.linuxfoundation.org/sites/events/files/slides/cec-wide_1.pdf

Full development changelog here:

https://lwn.net/Articles/685756/

Developers contributions here:

http://lkml.iu.edu/hypermail/linux/kernel/1607.3/00427.html

Hedda · 2016-11-16T19:35:08Z

Nice video from the Embedded Linux Conference with Hans Verkuil on this HDMI CEC implementation:

https://www.youtube.com/watch?v=Q6S2FabX2WA

glance- · 2017-01-06T10:19:35Z

For 4.10, the framework and drivers are moved out of staging.

Is there a plan on how libcec should use/co-exist with this? Or is the plan just to ignore it?

opdenkamp · 2017-01-06T10:21:06Z

The plan is to use it's raw mode for libCEC, but that'll be something for the next major release of libCEC

ekirei · 2017-06-29T10:34:35Z

Hi, are there any news about integrating with the Linux CEC Framework?
Just to know if this will be a very long development or there may be good news in a short time.

opdenkamp · 2017-07-13T08:36:42Z

It's going to take some time because unfortunately. Too many other things that need to be done ;)

nkichukov · 2017-11-20T13:44:57Z

Hello fellows,

Is there any progress on this new feature request?

This is the only feature that does not work in Kodi on Gentoo Linux on raspberry pi 3B that makes no use of any proprietary broadcom drivers/firmware.

Kodi development seems to have no interest into implementing direct CEC calls in their software to the new kernel framework, thus use of libcec will remain required.

I can do code testing if needed.

Cheers,
-Nik

Borck · 2018-01-22T17:30:40Z

Hallo,
I hope this can accelerate the dev a little bit, I have not tested it
Kwiboo@f4db703

Kwiboo · 2018-01-22T19:17:33Z

@Borck there is an open PR/RFC at #380 that includes that commit, the cec-framework adapter is used to enable CEC support in LibreELEC on Rockchip devices.

nkichukov · 2018-01-23T21:55:45Z

Excellent, I have tested it and it does implement the required functionality successfully! See:
#380 (comment) for more details.

Hedda · 2019-01-07T08:34:46Z

@opdenkamp any more thoughts on the Linux kernel's HDMI CEC framework and an libcec adapter?

opdenkamp · 2020-04-27T08:48:30Z

merged now #380
thanks!

Hedda · 2020-04-27T09:31:41Z

@opdenkamp Very cool! Does that mean that we will see a libcec 5.0.x release in the near future?

...and hay look! Almost on the 5th year anniversary of this feature request too! ;)

opdenkamp · 2020-04-27T09:54:20Z

yes, but there will also be a 4.x release that includes it

Hedda mentioned this issue Mar 26, 2015

new misc driver interface for amlogic cec codesnake/linux-amlogic-old#19

Closed

Hedda mentioned this issue Apr 11, 2016

Amlogic cec #198

Closed

Hedda changed the title ~~Compatibility with "HDMI CEC framework" support for the Linux kernel?~~ Compatibility with "HDMI CEC framework" support in mainline Linux 4.8 kernel and later? Oct 27, 2016

opdenkamp mentioned this issue Mar 15, 2017

Does libcec supports Android? #315

Closed

opdenkamp mentioned this issue Jul 13, 2017

MegaChips MCDP2800 LSPCON driver #280

Closed

Hedda mentioned this issue Jan 23, 2018

RFC: Linux CEC framework adapter #380

Merged

jmgirven mentioned this issue Jan 23, 2018

Zidoo smart TV box with libcec #401

Closed

opdenkamp closed this as completed Apr 27, 2020

opdenkamp reopened this Apr 27, 2020

opdenkamp closed this as completed Apr 27, 2020

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Compatibility with "HDMI CEC framework" support in mainline Linux 4.8 kernel and later? #67

Compatibility with "HDMI CEC framework" support in mainline Linux 4.8 kernel and later? #67

Hedda commented Mar 24, 2015 •

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glance- commented Jan 6, 2017

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opdenkamp commented Apr 27, 2020

Compatibility with "HDMI CEC framework" support in mainline Linux 4.8 kernel and later? #67

Compatibility with "HDMI CEC framework" support in mainline Linux 4.8 kernel and later? #67

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Hedda commented Mar 24, 2015 • edited Loading

opdenkamp commented Mar 24, 2015

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gdachs commented Apr 11, 2016

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