Re: git: ce881170088c - main - atkbd: Disable periodic polling by default.

On Wed, Jan 5, 2022 at 5:04 PM Gleb Smirnoff <glebius@freebsd.org> wrote:

> On Wed, Jan 05, 2022 at 04:18:25PM -0700, Warner Losh wrote:
> W> On Wed, Jan 5, 2022, 3:47 PM Gleb Smirnoff <glebius@freebsd.org> wrote:
> W>
> W> > On Wed, Jan 05, 2022 at 08:13:03PM +0000, Alexander Motin wrote:
> W> > A> commit ce881170088c4c98c036fe561f8ee8413c2e2585
> W> > A> Author:     Alexander Motin <mav@FreeBSD.org>
> W> > A> AuthorDate: 2022-01-05 20:00:36 +0000
> W> > A> Commit:     Alexander Motin <mav@FreeBSD.org>
> W> > A> CommitDate: 2022-01-05 20:12:58 +0000
> W> > A>
> W> > A>     atkbd: Disable periodic polling by default.
> W> > A>
> W> > A>     It is one of the few remaining Giant-locked callouts.  It
> would be
> W> > A>     good to remove it, not mentioning that polling itself is not
> good.
> W> > A>
> W> > A>     If this cause keyboard/mouse freezes on some hardware, please
> set
> W> > A>     loader tunable hw.atkbd.hz=1 as workaround and report the
> issue.
> W> > A>
> W> > A>     Submitted by:   imp, jhb
> W> >
> W> > Lame question: this is related only to a keyboard plugged into PS/2,
> isn't
> W>
> W> Yes. I think this part of the code is only for "legacy" keyboards. I
> don't
> W> think mice are affected, but since both attach to the keyboard
> controller
> W> there is a tiny chance mice might be affected in some weird hardware...
>
> I'd even say to legacy mainboards. Cause I have PS/2 keybooard plugged into
> USB port and AFAIU it is not affected by this change in any way.
>

correct. Going through USB is unaffected.


> I think that even if this change creates some regression, we never know
> that.
> Nobody would today run so old mainboard as a desktop. Might have it as a
> headless appliance.
>

You'd be surprised what people run today :(. Doing the graphics stuff has
shown
me that. Nobody would build a new one today, but there's lots of systems
that have
been around a few years that have keyboards connected via PS/2. I doubt,
though,
any will see a regression because of the extreme age of this workaround.

Warner