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Message-ID: <CAErSpo6eB=Gn6wPBK=_KYhP=NOi26AmuJd_rS-zAw+2ERdrcew@mail.gmail.com> Date: Fri, 11 Jan 2013 11:06:29 -0700 From: Bjorn Helgaas <bhelgaas@...gle.com> To: "Rafael J. Wysocki" <rjw@...k.pl> Cc: Yinghai Lu <yinghai@...nel.org>, 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> Subject: Re: [PATCH v3 3/6] ACPI/pci_slot: update PCI slot information when PCI hotplug event happens On Thu, Jan 10, 2013 at 4:59 PM, Rafael J. Wysocki <rjw@...k.pl> wrote: > On Thursday, January 10, 2013 03:40:45 PM Yinghai Lu wrote: >> On Thu, Jan 10, 2013 at 3:39 PM, Rafael J. Wysocki <rjw@...k.pl> wrote: >> > 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. >> >> add one command line to control it so do not claim that in osc_control? > > That's one option, although not very attractive so to speak. > >> >> 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. >> >> Yes. >> >> maybe we can have pci=nopciehp in command line just we pci=noaer... >> >> that should handle some corner cases. > > Yes. In any case the user should be able to say "I know better", but having > to express that through the "right" ordering of modules is somewhat less than > straightforward in my opinion. I think it's fine if a user *can* override the default ordering. I am completely opposed to *requiring* a user to supply a command line option or change the order of module loading just to get hotplug to work. There's no sane way to document that or communicate that information to users. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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