From: Lukas Wunner <lukas@wunner.de>
To: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Jesse Barnes <jbarnes@hobbes.lan>, Ingo Molnar <mingo@elte.hu>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/early-quirks: Scan all functions in early_pci_scan_bus()
Date: Mon, 17 Aug 2026 10:19:12 +0200 [thread overview]
Message-ID: <aoLEAD_8GgzuDtYK@wunner.de> (raw)
In-Reply-To: <aoIiEZmqsOOwS6KX@linux.dev>
On Sun, Aug 16, 2026 at 10:48:17PM +0200, Thorsten Blum wrote:
> On Sun, Aug 16, 2026 at 07:25:22AM +0200, Lukas Wunner wrote:
> > On Fri, Aug 07, 2026 at 11:46:02AM +0200, Thorsten Blum wrote:
> > > early_pci_scan_bus() stops scanning a PCI slot when check_dev_quirk()
> > > returns nonzero, which avoids probing functions 1-7 on single-function
> > > devices, but also stops scanning when a function is absent on a
> > > multifunction device.
> > >
> > > This can skip early quirks on multifunction devices with holes in their
> > > function numbering.
> >
> > Which device do you need this for? We should only scan additional
> > Functions if a quirk needs to applied to them because this extends
> > boot time. It requires a justification and shouldn't be done "just
> > because".
>
> On iMac13,1 and iMac13,2, the BCM4331 AirPort card is behind root port
> 00:1c.3, also documented by the model list in abb2bafd295f ("x86/quirks:
> Add early quirk to reset Apple AirPort card").
>
> Public lspci output for 2012 iMacs [1][2] shows that 00:1c.0, 00:1c.2,
> 00:1c.3 and 00:1c.4 are present, but 00:1c.1 is missing. The old code
> stops at 00:1c.1 and never reaches 00:1c.3, so the AirPort reset quirk
> is silently skipped on these machines.
>
> [1] https://forum.libreelec.tv/thread/26799-wifi-not-detected-on-2012-imac-in-11-0/
> [2] https://zoringroup.com/forum/5/7170/
Thanks for the explanation. Please include all of this information
in the commit message when respinning.
prev parent reply other threads:[~2026-08-17 8:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-07 9:46 [PATCH] x86/early-quirks: Scan all functions in early_pci_scan_bus() Thorsten Blum
2026-08-07 9:51 ` sashiko-bot
2026-08-16 5:25 ` Lukas Wunner
2026-08-16 20:48 ` Thorsten Blum
2026-08-17 8:19 ` Lukas Wunner [this message]
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