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Date:   Mon, 10 Dec 2018 16:24:52 -0600
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     "Grumbach, Emmanuel" <emmanuel.grumbach@intel.com>
Cc:     "bjorn@helgaas.com" <bjorn@helgaas.com>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "Mertarg10@gmail.com" <Mertarg10@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Fwd: [Bug 201647] New: Intel Wireless card 3165 does not get
 detected but bluetooth works
Message-ID: <20181210222452.GC85090@google.com>
References: <bug-201647-193951@https.bugzilla.kernel.org/>
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On Sun, Dec 02, 2018 at 06:57:35AM +0000, Grumbach, Emmanuel wrote:
> > On Fri, Nov 09, 2018 at 03:43:06PM -0600, Bjorn Helgaas wrote:
> > > ---------- Forwarded message ---------
> > > From: <bugzilla-daemon@bugzilla.kernel.org>
> > > Date: Fri, Nov 9, 2018 at 4:10 AM
> > > Subject: [Bug 201647] New: Intel Wireless card 3165 does not get
> > > detected but bluetooth works
> > >
> > > https://bugzilla.kernel.org/show_bug.cgi?id=201647
> > >
> > >             Bug ID: 201647
> > >            Summary: Intel Wireless card 3165 does not get detected but
> > >                     bluetooth works
> > >            Product: Drivers
> > >            Version: 2.5
> > >     Kernel Version: 4.19.1
> > >           Hardware: Intel
> > >                 OS: Linux
> > >               Tree: Mainline
> > >             Status: NEW
> > >           Severity: high
> > >           Priority: P1
> > >          Component: PCI
> > >           Assignee: drivers_pci@kernel-bugs.osdl.org
> > >           Reporter: Mertarg10@gmail.com
> > >         Regression: No
> > >
> > > This bug affects most of the devices with a Celeron N4000 and an Intel
> > > wifi 3165 Ac adapter.
> > >
> > > When using Linux wifi is not working however, Bluetooth is working
> > > fine.  Also, Bluetooth part of this chip is connected via btusb and
> > > the wifi part of this chip is connected via PCIe.
> > 
> > Can you attach a screenshot of the Windows 10 device manager info for the
> > wifi adapter to the bugzilla?  If you can get a raw hex dump of its config
> > space, that would be awesome.
> > 
> > Also attach a copy of your kernel .config file (typically in /boot/).
> > 
> > My only guess is that maybe the system keeps wifi completely powered
> > down and uses hotplug to add it when needed.  [1] mentions wifi being on
> > pcibus 1 under Windows.  Your lspci does show bridge 00:13.0 leading to bus
> > 01, but Linux doesn't find any devices on bus 01.
> > 
> > Hotplug could be done via either acpiphp (ACPI mediated hotplug) or pciehp
> > (native PCIe hotplug).  Your dmesg shows you do have acpiphp.
> > 
> > I can't tell about pciehp (your .config will show that), but I think pciehp will
> > only claim bridges where SltCap contains HotPlug+, and yours shows HotPlug-
> > , so I don't think pciehp will do anything on your system.
> > 
> > Even if the system does use hotplug, I don't know what mechanism the OS
> > would use to wake up the device, since we don't know it even exists.  I guess
> > there could be some magic switch accessible via USB.
> > But if that were the case, I'm sure Emmanuel would know about it.
> 
> Hm... Don't be so sure... :)
> I don't think we have anything as fancy as this.
> I guess you can try to dig into the BIOS settings?
> I have heard of such a switch that would make the device disappear.

It's worth looking, but I don't understand how a BIOS switch would
solve this problem.  I assume that with the same BIOS settings,
Windows works and Linux fails.

Maybe there would be a clue in an acpidump from affected machines,
e.g., maybe we'd see some kind of ACPI hotplug notification.  That
seems like a long shot because we do have acpiphp in the kernel, and
it *should* be handling such notifications, but it could always be
broken.

The Windows device manager info (requested above) would be
interesting.

Bjorn