[bug report] adlp_tc_phy_connect [i915] floods logs with drm_WARN_ON(tc->mode == TC_PORT_LEGACY) call traces

[Imre Deak]

On Mon, Jul 15, 2024 at 08:35:43PM +0200, Francesco Poli wrote:
> Hi all,
> on a laptop where I installed Debian testing some 6 months ago,
> I noticed that the logs are continuously flooded with call traces
> like the attached snippet (taken from /var/log/kern.log ).
> 
> It seems to me that it also used to happen with previous versions
> of the Linux kernel, but I am under the impression that, with Linux
> kernel 6.9.7, it got worse. I have recently upgraded to Linux kernel
> version 6.9.8 (provided by the distro, Debian testing, as I said), but
> the bug is still reproducible:
> 
>   $ uname -srvmo
>   Linux 6.9.8-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.9.8-1 (2024-07-07) x86_64 GNU/Linux
> 
> I see at least 12 of these call traces just after boot, before even
> starting X (with 'startx').
> More of these call traces are sent to the logs after starting X, or
> after invoking 'xrandr', or after locking the X session (with
> XScreenSaver), ...
> I always see these call traces (I mean the bug is always reproducible:
> each time I boot, each time I call xrandr, ...).
> 
> They seem to correspond to no actual issue, as far as I can tell,
> but they are flooding the logs with a significant flow of text...
> which is worrying by itself.
> 
> 
> What's wrong?
> How can I stop this log-filling flood?
> Should I black-list some module, for instance?
> 
> 
> The outputs of
> 
>   # lspci -vnn -d :*:0300
> 
> and of
> 
>   # dmidecode
> 
> are attached.
> Also, I booted with kernel parameters
> 'drm.debug=0xe log_buf_len=4M ignore_loglevel' and
> logged in as root right after the boot.
> The output of
> 
>   # dmesg
> 
> is attached.

Thanks for the logs. The VBT claims that the laptop has 1 USB-C
and 3 legacy DP connectors (the latter 3 being a bit odd on a laptop,
even if not impossible). The DMI in BIOS says:

DMI: Notebook NLxxPUx/NLxxPUx, BIOS 1.07.09 11/17/2023

for which I can't find the particular system to check the actual
configuration. Could you point to the laptop vendor/model's page or
describe what are the connectors on it?

Could you check if there is a BIOS upgrade available? Please follow up
on the gitlab issue as Jani suggested.

> Some additional information may be found on the [Debian bug] report I had previously filed.
> 
> [Debian bug]: <https://bugs.debian.org/1075770>
> 
> 
> N.B.:
> Please Cc me and the Debian bug address <1075770 at bugs.debian.org>
> on replies, so that the interested parties (including me!) are kept
> in the loop.
> Thanks a lot for your time and for any help you may provide!
> 
> 
> -- 
>  http://www.inventati.org/frx/
>  There's not a second to spare! To the laboratory!
> ..................................................... Francesco Poli .
>  GnuPG key fpr == CA01 1147 9CD2 EFDF FB82  3925 3E1C 27E1 1F69 BFFE