linux-kernel - PROBLEM: AST2500 BMC video output disabled by reboot (regression)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <wpwd7rit6t4mnu6kdqbtsnk5bhftgslio6e2jgkz6kgw6cuvvr@xbfswsczfqsi>
Date: Mon, 21 Apr 2025 00:26:33 -0400
From: Nick Bowler <nbowler@...conx.ca>
To: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	regressions@...ts.linux.dev
Cc: Douglas Anderson <dianders@...omium.org>
Subject: PROBLEM: AST2500 BMC video output disabled by reboot (regression)

Hi,

I recently noticed that on current kernels I lose video output from
my Blackbird's AST2500 BMC after a reboot, which makes it difficult to
boot the system again (the video output will come on only after Linux
is booted again).

With Linux 6.6 and earlier, there is no problem rebooting, everything
is fine.

I bisected to this commit:

  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

This commit does not revert cleanly on 6.14, but I can easily undo
the changes this commit made to the ast driver, and this is enough
to restore working behaviour.

Let me know if you need any more info!

Thanks,
  Nick