linux-kernel - Re: [PATCH 0/5] Detect hwmon and i2c bus drivers interfering with ACPI Operation Region resources

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Date:	Fri, 26 Oct 2007 07:09:19 -0600
From:	Bjorn Helgaas <bjorn.helgaas@...com>
To:	trenn@...e.de
Cc:	linux-acpi <linux-acpi@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Len Brown <lenb@...nel.org>, Andrew Morton <akpm@...l.org>,
	Jean Delvare <khali@...ux-fr.org>
Subject: Re: [PATCH 0/5] Detect hwmon and i2c bus drivers interfering with ACPI Operation Region resources

On Friday 26 October 2007 4:45:20 am Thomas Renninger wrote:
> On Thu, 2007-10-25 at 21:59 -0600, Bjorn Helgaas wrote:
> > On Thursday 25 October 2007 4:55:07 pm Thomas Renninger wrote:

> > > Also the BIOS developers seem to choose the regions in a very dump way
> > > sometimes.
> > > Just some imaginary values, but I saw similar (overlapping):
> > >  - For a PNP device IO ports from 0x400-0x410 are reserved
> > >  - A operation region is declared from 0x399-0x401
> >
> > If we know the resources the opregion can use, we can at least
> > reserve the union of those used by the opregion and by other
> > PNP devices.  A little messy to deal with overlapping areas, I
> > agree, but it should still be possible by shrinking the region
> > or allocating a port at a time or something.
>
> You mean merging them together to something like:
>   0x400-0x410 pnp device
>   0x399       ACPI Op region's name
> This needs touching of kernel/resource.c and modification in a very ugly
> way affecting all architectures...

Right, that's what I was thinking.  But I haven't tried it, so I'll
take your word for it that it's ugly.

> Maybe the list set up by this patch set should be similarly exported
> like /proc/ioports /proc/iomem
> to where ever appropriate (maybe /sys/devices/system/acpi/opreg_io
> and /sys/devices/system/acpi/opreg_mem?) to get a better overview what
> kind of devices are served by the Op regions on different machines.

I want to try hard to avoid making ACPI a special case in this way.
The current /proc/io{ports,mem} contains reservations for everything
else.  I'd hate to have to look two places just because of ACPI.

> I think I worked on something else.
> Do I get this right:
> This one is to request all active resources of all ACPI devices that
> export resources via _CRS/_SRS?
> As this is currently done for the motherboard devices only by
> pnp/system.c?

Right.  Actually my patch requests resources of all active PNP devices,
not just ACPI.  Glad we didn't do overlapping work here :-)

> If you are interested I can try to fast cleanup and send you a
> pre-version of all patches (but not before beginning of next week).

Thanks for the preview.  No hurry as far as I'm concerned.

Bjorn
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