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Re: [PATCH] Input: i8042-io - Exclude mips platforms when allocating/dea

To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: Re: [PATCH] Input: i8042-io - Exclude mips platforms when allocating/deallocating IO regions.
From: Aaro Koskinen <aaro.koskinen@iki.fi>
Date: Mon, 27 Jan 2014 22:24:35 +0200
Cc: Raghu Gandham <Raghu.Gandham@imgtec.com>, "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>, "linux-mips@linux-mips.org" <linux-mips@linux-mips.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Hi,

On Sun, Jan 26, 2014 at 10:56:38PM -0800, Dmitry Torokhov wrote:
> On Mon, Jan 27, 2014 at 12:32:36AM +0000, Raghu Gandham wrote:
> > > On Sat, Jan 25, 2014 at 11:01:54AM -0800, Raghu Gandham wrote:
> > > > The standard IO regions are already reserved by the platform code on
> > > > most MIPS devices(malta, cobalt, sni). The Commit
> > > > 197a1e96c8be5b6005145af3a4c0e45e2d651444
> > > > ("Input: i8042-io - fix up region handling on MIPS") introduced a bug
> > > > on these MIPS platforms causing i8042 driver to fail when trying to
> > > > reserve IO ports.
> > > > Prior to the above mentioned commit request_region is skipped on MIPS
> > > > but release_region is called.
> > > >
> > > > This patch reverts commit 197a1e96c8be5b6005145af3a4c0e45e2d651444
> > > > and also avoids calling release_region for MIPS.
> > > 
> > > The problem is that IO regions are reserved on _most_, but not _all_
> > > devices.
> > > MIPS should figure out what they want to do with i8042 registers and be
> > > consistent on all devices.
> > 
> > Please examine the attached patch which went upstream in April of 2004.
> > Since then it had been a convention not to call request_region routine in
> > i8042 for MIPS. The attached patch had a glitch that it guarded
> > request_region in i8042-io.h but skipped guarding release_region in
> > i8042-io.h. I believe that the issue Aaro saw was due to this 
> > glitch. Below is the error quoted in Aaro's commit message.
> > 
> >     [    2.112000] Trying to free nonexistent resource 
> > <0000000000000060-000000000000006f>
> > 
> > My patch reinstates the convention followed on MIPS devices along with
> > fixing Aaro's issue.
> 
> I assume that Aaro did test his patch and on his box request_region()
> succeeds. That would indicate that various MIPS sub-arches still not
> settled on the topic.

request_region() succeeds on Loongson and OCTEON.

On OCTEONs without PCI, request_region() will fail which is correct as
there is no I/O space.

I wasn't aware of that 2004 patch (it pre-dates GIT history of mainline
Linux). Why the regions are already reserved by the platform code?

A.

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