linux-kernel - Re: [PATCH] PCI: Remove not needed check in disable aspm link

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Message-ID: <CAE9FiQUO350kqrXB5=yQ-OxOeSJj4+P6WPg4gGgXxFEvfoLyng@mail.gmail.com>
Date:	Fri, 14 Jun 2013 09:57:30 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Jiang Liu <jiang.liu@...wei.com>,
	Roman Yepishev <roman.yepishev@...il.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] PCI: Remove not needed check in disable aspm link

On Fri, Jun 14, 2013 at 9:33 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> On Fri, Jun 14, 2013 at 10:17 AM, Yinghai Lu <yinghai@...nel.org> wrote:
>
> Can you please refer to specific function names?  I can't read your mind.
>
> You might be referring to quirk_disable_aspm_l0s().  This is a
> pci_fixup_final quirk that calls pci_disable_link_state().  In the
> current tree, we enumerate devices before requesting _OSC control.
> However, pci_fixup_final quirks are not run until the
> pci_apply_final_quirks() fs_initcall, which is after we request _OSC
> control.
>
> As far as I can tell, we never call pci_disable_link_state() before
> calling pcie_no_aspm().

ok, you are right, that is not pci_disable_link_state.

It is pcie_aspm_init_link_state ==> pcie_aspm_sanity_check in booting path
that disable aspm.  It has  "if (aspm_disabled)" in it, and it cause
the difference.

Yinghai
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