linux-kernel - Re: [PATCH v3 3/6] ACPI/pci_slot: update PCI slot information when PCI hotplug event happens

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Message-ID: <1410202.K95a8u1BYT@vostro.rjw.lan>
Date:	Fri, 11 Jan 2013 00:39:12 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Myron Stowe <mstowe@...hat.com>, Jiang Liu <liuj97@...il.com>,
	Jiang Liu <jiang.liu@...wei.com>,
	Yijing Wang <wangyijing@...wei.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	Myron Stowe <myron.stowe@...hat.com>,
	bhelgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v3 3/6] ACPI/pci_slot: update PCI slot information when PCI hotplug event happens

On Thursday, January 10, 2013 03:03:53 PM Yinghai Lu wrote:
> On Thu, Jan 10, 2013 at 1:50 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > Well, I don't see what functional problems that can bring.
> >
> > In theory people may want to have them as modules to avoid loading them on
> > systems that don't use PCI hotplug, but honestly I think that the complexity
> > this causes us to deal with is not worth it.
> >
> > Moreover, removing the modularity may actually allow us to solve some ordering
> > issues once and for good.
> 
> No, the world is not really ideal yet.
> 
> looks like laptops have problem with pci express cards.
> 
> when pciehp is used, surprise insert/removal does not work because
> PresDect does not change properly, so no interrupt is generated.
> --- i suspects that is silicon problem.
> 
> but when acpiphp is used, that surprise  insert/removal is working.
> 
> some laptop like thinkpad, just don't give osc to kernel..
> [    0.505117]  pci0000:00: Requesting ACPI _OSC control (0x1d)
> [    0.505413]  pci0000:00: ACPI _OSC request failed (AE_SUPPORT),
> returned control mask: 0x0d
> [    0.505517] ACPI _OSC control for PCIe not granted, disabling ASPM
> 
> and other laptop give that to kernel, in recent kernel will not give
> acpiphp to have that slot, because it want to hold that for pciehp.
> poor user have to pass 'pci_aspm=off" to disable _OSC for all.
> --- please check the mail that i forward to you yesterday.

Yes, this is a bug, but I'm not sure how to fix it yet.

> Anyway, we do need to let the user to have choice to use acpiphp and pciehp.
> and it should be first come and first serve policy.

And that's why you think they should be modules?  I disagree if so.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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