linux-kernel - Re: post 2.6.26 requires pciehp_slot_with

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Message-Id: <200807280916.44664.jbarnes@virtuousgeek.org>
Date:	Mon, 28 Jul 2008 09:16:44 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Cc:	Pierre Ossman <drzeus-list@...eus.cx>,
	Alex Chiang <achiang@...com>,
	LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
	Kristen Accardi <kristen.c.accardi@...el.com>
Subject: Re: post 2.6.26 requires pciehp_slot_with_bus

On Monday, July 28, 2008 1:44 am Kenji Kaneshige wrote:
> Jesse Barnes wrote:
> > I think that's fine (automatically creating duplicate devices with names
> > to differentiate them), but I think we should also try harder to avoid
> > adding duplicates.
> >
> > In Pierre's case, and on my T61, there's only one actual hotplug slot
> > available, but the firmware creates duplicate physical slot numbers and
> > sets the HP_CAP bit on everything, both of which are obviously wrong
> > (well I suppose you could pop these chips off the board, but it's not
> > very practical).  However, afaict that "other" OS uses the _RMV method to
> > determine whether a given slot is actually hot pluggable.  On my T61 at
> > least, this seems to be accurate: only one of my EXP* objects has a _RMV
> > method.
> >
> > So maybe the PCIe hotplug driver should be checking for that method when
> > ACPI is available?  We already try to use _OSC etc., so checking for _RMV
> > first would make sense...
>
> As you pointed out, the root cause might not a problem of slot naming,
> but a problem of slots detection, because pciehp driver detects multiple
> PCIe hotplug slots even thought your and Pierre's system seems to have
> only one hotplug slot. So I think we should also consider the problem
> from this view point (slot detection).
>
> But, I think simply checking for _RMV method first is dangerous because
> I think there are many systems that doesn't implement _RMV for PCIe
> hotplug slots (at least, my system doesn't implement that. Anyway,
> I would like to look at the documents/specifications that mention _RMV
> method for determining whether a given slot is hot pluggable. Do you
> have any information about that? I think PCI Local Bus, PCI Express and
> PCI Firmware specification don't mention that. I think hot pluggable slots
> on your, Pierre's and Matthew's system are ExpressCard slots. So I guess
> ExpressCard specification might define something about this. But
> unfortunately, I don't have ExpressCard specification. Can anyone access
> ExpressCard spec?

Your systems don't have _RMV methods for the hotpluggable PCIe slots in the 
DSDT?  That's a shame; the Windows docs I found on PCIe hotplug seemed to 
indicate that _RMV and _OSC (under Vista) were used to detect whether a given 
slot was hot pluggable (I just googled for "windows pcie hotplug" or 
something) so I was hoping that would be a reliable method...  Any other 
ideas?  I'll go see if I can dig up some ExpressCard info.

Thanks,
Jesse
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