Latest TBS-fork driver breaks i915

pchristy · 04-06-2020, 05:28 AM

System: Slackware64-current (up-to-date)
Gfx: VGA compatible controller: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller (rev 06)
TBS-driver: TBS forked driver (instructions here: https://www.linuxtv.org/wiki/index.p...r_installation

The problem: The latest TBS-fork driver breaks the i915 driver.

I have a TBS 6281SE tuner card in my PC for watching and recording TV. For Linux, TBS advise using the open source drivers for which intructions can be found via the link above.

TBS-fork is a fork of the original open source ljalves driver. The ljalves driver hasn't been updated in a long time, and appears dormant.

The TBS-fork driver has worked fine for me until the latest updates. These completely break the i915 driver:

Code:

Before installing driver:

Kernel-5.4.30 dmesg | grep i915
[    6.753039] i915 0000:00:02.0: vgaarb: deactivate vga console
[    6.753818] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem
[    6.755940] [drm] Initialized i915 1.6.0 20190822 for 0000:00:02.0 on minor 0
[    6.757401] snd_hda_intel 0000:00:03.0: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])
[    6.797757] fbcon: i915drmfb (fb0) is primary device
[    6.845283] i915 0000:00:02.0: fb0: i915drmfb frame buffer device

After installing driver:

Kernel-5.4.30 dmesg | grep i915
[    7.410856] i915: Unknown symbol cec_notifier_put (err -2)
[    7.464552] i915: Unknown symbol cec_notifier_put (err -2)
[   16.064911] i915: Unknown symbol cec_notifier_put (err -2)
[   16.079576] i915: Unknown symbol cec_notifier_put (err -2)

I have notified the developer, who says the problem is with the upstream v4l stuff, and must await fixes there. However, Slackware64-current seems to come with the same v4l stuff (the dates match, anyway!) and doesn't have the problem.

Until this problem arose a week ago, I was running kernel-5.4.14, and the TBS driver from late January / early February without any problems. When I updated to kernel-5.4.30, I needed to rebuild the TBS driver and did a git update and rebuild as described in the wiki. On installing, I got the above errors.

I now also get the same errors when compiling against 5.4.14, which previously worked fine.

Bear in mind that I am NOT a programmer or developer, but I am reasonably computer literate! My knowledge of git is extremely limited! I believe it should be possible to pull an earlier version of the drivers (pre-mid February, which is when the critical changes occurred), but I have little or no idea how to do this! Google turned up some instructions clearly aimed at developers with a fair amount of prior knowledge that I do not posses!

So question 1: Can someone provide an "idiots guide" to retrieve an earlier version of this driver?

Question 2: If the versions of v4l in slackware and the TBS driver are the same, why is this error occurring?

Over to the experts, and TIA!

--
Pete

business_kid · 04-06-2020, 02:01 PM

Code:

 Unknown symbol cec_notifier_put

I'd find that symbol first - it tells you what the library is. I did a quick search on DDG but wasn't rewarded. you can grep the sources and binary libs.

Ian M · 04-06-2020, 03:18 PM

If you want to find an earlier version of the driver go here https://github.com/tbsdtv/media_build/commits/master this lists all the commits to the project. Next to each one on the right is an icon "<>" clicking this will take you to how the repository was at that point eg: this is at the 27th January https://github.com/tbsdtv/media_buil...dbde74b48a614e you can then click the "clone or download" button and download it as zip, you can't use the clone option, that just gets you the latest version.

Hope that helps.

bassmadrigal · 04-06-2020, 03:42 PM

Quote:

Originally Posted by pchristy

So question 1: Can someone provide an "idiots guide" to retrieve an earlier version of this driver?

If you're just talking about an earlier version of the TBS driver (and I'm assuming you mean the tbsdtv fork), you'd just view the commits for the project. Then you look through the commits and click on the one you want to try. From there, it will pop up a page explaining what that commit did and what files were affected. Then you'd just click the "Browse Files" button in the upper right and then you can click on the clone/download button and download that snapshot in a zip.

If you want the download to be a tar.gz file with decent naming, you'd take the link to the zip and convert it like below:

Code:

https://github.com/tbsdtv/media_build/archive/4bc8680a31802ed323238245c41ad9b1cf37bf6a.zip
https://github.com/tbsdtv/media_build/archive/4bc8680/media_build-4bc8680a31802ed323238245c41ad9b1cf37bf6a.tar.gz

If you really wanted to dig through the problem, you could look at git bisect, which will help find what commit ultimately caused the issue. There's a lot of resources online on how to use git bisect, but a quick one I found is this stackoverflow question with several strong answers covering it.

Quote:

Originally Posted by pchristy

Question 2: If the versions of v4l in slackware and the TBS driver are the same, why is this error occurring?

No clue on this.

Quote:

Originally Posted by business_kid

Code:

 Unknown symbol cec_notifier_put

I'd find that symbol first - it tells you what the library is. I did a quick search on DDG but wasn't rewarded. you can grep the sources and binary libs.

cec_notifier_put is part of the kernel and located under include/media/cec-notifier.h. Using grep through my kernel sources extracted on my computer, it has been present in the kernel since at least 4.13.7 and is present in 5.4.30 (the latest I have installed).

pchristy · 04-07-2020, 02:51 AM

Thanks to all who have replied! Some of you will know that I'm a Brit, living in the UK, so a bit of a time difference between here and the States. Most of these replies came in late evening here, hence my delayed response!

Ian_M: Thanks for that tip! That was what I was looking for, but couldn't work out. I was expecting it to be some kind of clone command for git, but couldn't find it. Now I know why!

business_kid & bassmadrigal: My first priority is to get the driver working again. Hopefully I can do this by simply reverting to an earlier version. Once I've achieved that, I can play around trying to determine exactly where the problem has crept in on an old "test" kernel. The info you have provided will be a big help.

Looking at the v4l-utils github page (https://git.linuxtv.org/v4l-utils.git/), I see a lot of references to cec since the middle of March. I've no idea (yet) if these are relevant or not. I also need to look at the Slackware v4l-utils package and see if it contains any patches.

Could be a busy morning, but breakfast first, methinks!

--
Pete

pchristy · 04-07-2020, 05:01 AM

OK, had a chance to have a play with this, but got nowhere!

First I downloaded both the media_build and (linux-)media trees from the 27th of January and tried to build the driver against kernel-5.4.14. I ran into exactly the same cec error. Looking at my 5.4.14 kernel, it looks like I installed it on the 24th of January. I therefore went back to the trees from the 24th of January, but these failed at the stage of installing patches and refused to build.

I think I have to admit that I'm now out of my depth! Either I have to wait for the developers to fix whatever it is that's broken, or stop using the on-board graphics and get a plug-in graphics card. I really don't want to do the latter as I don't play games and don't need 3D graphics. The Intel is as good as anything else at handling video - indeed better, or at least easier, if I need to use hardware encoding.

This is very frustrating as it has all been working perfectly for a couple of years now, but I think I have to concede defeat - for the moment, at least.

--
Pete