linux-kernel - Re: [PATCH] Input: serio: make HYPERV_KEYBOARD depend on SERIO

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Date:	Tue, 12 Aug 2014 10:54:35 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Dexuan Cui <decui@...rosoft.com>
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"driverdev-devel@...uxdriverproject.org" 
	<driverdev-devel@...uxdriverproject.org>,
	"olaf@...fle.de" <olaf@...fle.de>,
	"apw@...onical.com" <apw@...onical.com>,
	"jasowang@...hat.com" <jasowang@...hat.com>,
	KY Srinivasan <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>
Subject: Re: [PATCH] Input: serio: make HYPERV_KEYBOARD depend on
 SERIO_I8042=y

On Tue, Aug 12, 2014 at 07:15:25AM +0000, Dexuan Cui wrote:
> > -----Original Message-----
> > From: linux-kernel-owner@...r.kernel.org [mailto:linux-kernel-
> > owner@...r.kernel.org] On Behalf Of Greg KH
> > > > What exactly needs to be done to fix this "correctly" that is going to
> > > > take too much work at the moment?
> > >
> > > To decouple the dependency between the hyperv-keyboard and i8042
> > > modules, I suppose we probably have to re-implement hyperv-keyboard by
> > > using input_allocate_device(), input_register_device(), and using
> > > input_report_key() to pass the key strokes to the high level.
> > 
> > Yes, that would be the best thing to do,

Why? The backend still delivers AT keyboard data, so why does it make
sense to write a new driver instead of making sure you can load
atkbd/libps2 even without i8042 loaded?

> > and shouldn't be that hard to
> > create an input driver, it's pretty simple code, right?
> Hi Greg,
> Thanks for the confirmation!
> I didn't use the APIs before. 
> I think I need a couple of days to code, test and debug it while I have many
>  things at hand at present. :-(
> 
> > > I'll have to need some time for further investigation and a new
> > > implementation. Before the new code is completely ready, IMHO the
> > > patch can help to avoid a bad user experience like Arch Linux working
> > > as a Generation 2 hyper-v guest.
> > 
> > You are still preventing Arch from working here, as the driver can't be
> > built at all, right?
> The driver can build(compile) fine.
> The issue is: the latest Arch Linux release doesn't have a working (virtual)
> keyboard when it runs as Generation 2 hyper-v guest -- when it runs as
> a "traditional" Generation 1 hyper-v guest, everything works fine.
> I hope this patch can temporarily help Arch users if they find the issue
> and if they can rebuild the kernel.

The Arch users can simply select to build i8042 into the kernel as a
workaround.

The proper solution is to allow loading libps2 module even if i8042 did
not find its device. I wish I could simply drop this i8042_lock_chip and
stuff, but unfortunately i8042 ports are not truly independent. We need
to figure a way for libps2 to engage locking in i8042 if the driver is
loaded, otherwise just ignore it.

Thanks.

-- 
Dmitry
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