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From: Lukas Wunner <lukas@wunner.de>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	cmilsted@redhat.com, Rafa?? Mi??ecki <zajec5@gmail.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Matt Fleming <matt@codeblueprint.co.uk>,
	Peter Zijlstra <peterz@infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Matthew Garrett <mjg59@srcf.ucam.org>,
	m@bues.ch,
	"linux-tip-commits@vger.kernel.org" 
	<linux-tip-commits@vger.kernel.org>
Subject: Re: [tip:x86/urgent] x86/quirks: Add early quirk to reset Apple AirPort card
Date: Wed, 8 Jun 2016 22:09:29 +0200	[thread overview]
Message-ID: <20160608200929.GA18981@wunner.de> (raw)
In-Reply-To: <CAE9FiQVapnZ8akNWLo-c8sD4enA1qGcW50vmv7_-9g78Hsm4sg@mail.gmail.com>

On Wed, Jun 08, 2016 at 11:56:14AM -0700, Yinghai Lu wrote:
> On Wed, Jun 8, 2016 at 7:23 AM, tip-bot for Lukas Wunner <tipbot@zytor.com> wrote:
> > --- a/arch/x86/kernel/early-quirks.c
> > +++ b/arch/x86/kernel/early-quirks.c
> ...
> 
> Extend bus scan range part should be in separated patch?
> 
> and put apple_airport_reset() related in second patch.

I had considered that but decided against it as it would make things
a bit more complicated for stable maintainers.

Nevertheless I'll be happy to split in two if this is the consensus?
I'm not sure though if x86/urgent is a rebasing branch?


> > +
> > +       if ((type & 0x7f) == PCI_HEADER_TYPE_BRIDGE) {
> > +               sec = read_pci_config_byte(num, slot, func, PCI_SECONDARY_BUS);
> > +               early_pci_scan_bus(sec);
> 
> How do you know that sec is valid ?
> 
> How about on the system that have one bridge that still have sec num register 0?
> 
> it will be get into dead loop.

Good point. I've just checked pci_scan_bridge() and it does verify that
and avoids recursing to a child bus if it's number is zero. It also
ensures that sec > num before recursing.

I can provide a follow-up patch to fix that, will wait a bit though to
see if there are further comments.


> > -void __init early_quirks(void)
> > +static void __init early_pci_scan_bus(int bus)
> >  {
> >         int slot, func;
> >
> > -       if (!early_pci_allowed())
> > -               return;
> > -
> >         /* Poor man's PCI discovery */
> > -       /* Only scan the root bus */
> >         for (slot = 0; slot < 32; slot++)
> >                 for (func = 0; func < 8; func++) {
> >                         /* Only probe function 0 on single fn devices */
> > -                       if (check_dev_quirk(0, slot, func))
> > +                       if (check_dev_quirk(bus, slot, func))
> >                                 break;
> >                 }
> >  }
> > +
> > +void __init early_quirks(void)
> > +{
> > +       if (!early_pci_allowed())
> > +               return;
> > +
> > +       early_pci_scan_bus(0);
> > +}
> 
> Would just revert to scan domain 0, bus 0 to 255.

The commit message of 8659c406ade3 sounds like this would lengthen
boot time noticeably, so I expected significant backlash had I just
gone back to this old algorithm.

Thanks,

Lukas

  reply	other threads:[~2016-06-08 20:05 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-28 23:35 [PATCH] x86: " Lukas Wunner
2016-05-28 23:35 ` Lukas Wunner
2016-06-02  9:48 ` Matt Fleming
2016-06-02  9:48   ` Matt Fleming
2016-06-08 14:23 ` [tip:x86/urgent] x86/quirks: " tip-bot for Lukas Wunner
2016-06-08 18:56   ` Yinghai Lu
2016-06-08 20:09     ` Lukas Wunner [this message]
2016-06-09  6:48       ` Ingo Molnar
2016-06-09 11:04         ` Lukas Wunner
2016-06-09 16:37           ` Yinghai Lu
2016-06-09 20:20             ` Lukas Wunner
2016-06-10  0:04               ` Yinghai Lu
2016-06-10 11:58                 ` Ingo Molnar
2016-06-10 12:16                   ` Lukas Wunner
2016-06-10 12:59                     ` Ingo Molnar
2016-06-10 13:59                       ` Lukas Wunner
2016-06-10 20:08                         ` Bjorn Helgaas
2016-06-12 11:13                           ` Lukas Wunner
2016-06-09 22:57 ` [PATCH] x86: " Bjorn Helgaas
2016-06-09 22:57   ` Bjorn Helgaas
2016-06-12 10:31 [PATCH v2 3/3] x86/quirks: " Lukas Wunner
2016-07-10 19:01 ` [tip:x86/urgent] " tip-bot for Lukas Wunner

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