Re: Is it possible to reset graphics controller on reboot in a framebuffer driver?

From: Tom Li
Date: Thu Mar 07 2019 - 16:38:16 EST

On Thu, Mar 07, 2019 at 10:39:23AM +0100, Geert Uytterhoeven wrote:
> On Thu, Mar 7, 2019 at 10:00 AM Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote:
> > It's possible to do this using a reboot notifier. I am not sure if there
> > are better ways to achieve the same, but there's at least one example of
> > using reboot notifiers to achieve the exact same goal.
> >
> > See drivers/video/fbdev/aty/atyfb_base.c, look for
> > register_reboot_notifier().
> Or a shutdown handler, which is more device-centric?
> (cfr. "[3/4] fbdev: atafb: Fix broken frame buffer after kexec",
> Gr{oetje,eeting}s,

Thanks, I knew reboot_notifier but I thought it feels "hacky" to use it in a
device driver, shutdown() handler looks better.

Nevertheless, does it mean there's no way to prevent it from happening if the
user issues a emergency reboot? Like an automatic reboot after a kernel panic,
or a SysRq-B reboot.

Tom Li