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Message-ID: <nchsanp7nc7nqy3kqlu7c5iwvfj6vmrkqbxyjxmoc5eq3dthjk@fusw4pm52auq>
Date: Wed, 30 Apr 2025 13:52:05 -0400
From: Nick Bowler <nbowler@...conx.ca>
To: Doug Anderson <dianders@...omium.org>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
regressions@...ts.linux.dev
Subject: Re: PROBLEM: AST2500 BMC video output disabled by reboot (regression)
Hi,
On Wed, Apr 30, 2025 at 10:05:44AM -0700, Doug Anderson wrote:
> On Wed, Apr 30, 2025 at 6:28 AM Nick Bowler <nbowler@...conx.ca> wrote:
> > On Mon, Apr 28, 2025 at 01:40:25PM -0700, Doug Anderson wrote:
> > > On Sun, Apr 20, 2025 at 9:26 PM Nick Bowler <nbowler@...conx.ca> wrote:
> > > > I recently noticed that on current kernels I lose video output from
> > > > my Blackbird's AST2500 BMC after a reboot
> > [...]
> > > > ce3d99c8349584bc0fbe1e21918a3ea1155343aa is the first bad commit
> > > > commit ce3d99c8349584bc0fbe1e21918a3ea1155343aa
> > > > Author: Douglas Anderson <dianders@...omium.org>
> > > > Date: Fri Sep 1 16:39:53 2023 -0700
> > > >
> > > > drm: Call drm_atomic_helper_shutdown() at shutdown time for misc drivers
[...]
> Do you happen to have anything that's just a normal HDMI sink, like a
> TV or a standard monitor that takes HDMI?
I can probably find something else to try later.
> > To clarify, there is no boot failure. There is just no video output
> > after rebooting. I can then boot Linux again by any method that works
> > without being able to see the screen, and then everything is fine once
> > I do that.
>
> Super weird. So every other boot works?
On a new/broken kernel, every time I run "reboot" the video turns off
when Linux does whatever it does to make the system restart.
The video comes on again if I manage to boot it up again.
The problem is that I have to do that without using the screen. So I
can boot Linux via the serial port, or via the BMC web interface, or
by just typing on the keyboard without seeing what is happening.
> I guess I'd be interested in other types of tests to see what's going
> on. Aside from trying some other, more standard HDMI sinks, I'd love
> to see the results of:
>
> 1. HDMI is supposed to be hotpluggable. If you've got a boot where the
> display isn't working, what if you unplug the HDMI and plug it back
> in. Does it fix it?
Unplugging/replugging the cable when the video is off after rebooting
does not cause it to start working again.
> 2. Does the hotplug experience change if you boot with the revert?
> AKA: boot up with the revert (so everything is working normally),
> unplug HDMI, wait a few seconds, plug HDMI back in? Is this different
> than #1?
I have certainly never noticed any problem related to hot plugging while
the video output is working but this is not something I ever normally
do. I can try it later.
> 3. What about if you fully power off and then power on? Does the
> display work reliably in this case, or are things different between
> ToT and with the revert?
There is never any problem with the video output if I fully power off/on
the system. The problem only occurs on a reboot.
> 4. What about if you fully power off, unplug the HDMI, wait a few
> seconds, plug the HDMI, and power on? Does that work? Are things
> different between ToT and with the revert?
Again there is never any problem if I fully power off/on the system.
Thanks,
Nick
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