linux-kernel - Re: [PATCH 1/2] power: reset: Add QEMU virt-ctrl driver

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Message-ID: <aWkGAEEpTBn5Fch8@google.com>
Date: Thu, 15 Jan 2026 23:21:36 +0800
From: Kuan-Wei Chiu <visitorckw@...il.com>
To: Daniel Palmer <daniel@...f.com>
Cc: geert@...ux-m68k.org, sre@...nel.org, jserv@...s.ncku.edu.tw,
	eleanor15x@...il.com, linux-kernel@...r.kernel.org,
	linux-m68k@...ts.linux-m68k.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 1/2] power: reset: Add QEMU virt-ctrl driver

Hi Daniel,

On Thu, Jan 15, 2026 at 10:29:29PM +0900, Daniel Palmer wrote:
> Hi Kuan-Wei,
> 
> On Thu, 15 Jan 2026 at 15:15, Kuan-Wei Chiu <visitorckw@...il.com> wrote:
> 
> > > FWIW: I have a driver for this in my "m68k with devicetree" tree. As
> > > far as I could tell the virt_ctrl thing in QEMU might get more
> > > features aside from power control.
> > > So I made it a misc device instead.
> >
> > Thanks for the note.
> > Just out of curious, are there currently specific plans to add
> > non-power features to virt_ctrl?
> 
> The docs here suggest that power control is the only currently
> implemented feature but doesn't have to be the only feature:
> https://github.com/qemu/qemu/blob/master/docs/specs/virt-ctlr.rst
> 
> > If new features are added, shouldn't they be exposed via separate
> > drivers in their respective subsystems, rather than consolidating
> > everything into a misc driver?
> 
> I guess if it did get new features maybe it'd be a multifunction
> device? Since nothing except power control has ever actually been
> implemented, maybe the way you have it right now makes the most sense.
> 
I agree that migrating to an MFD architecture would be the right move
if/when qemu implements additional features. For now, I will stick to
the current approach in drivers/power/reset as it fits the existing
functionality best.

Thanks again for your feedback.

Regards,
Kuan-Wei