linux-kernel - Re: [PATCH] PCI/portdev: Disable AER for Titan Ridge 4C 2018

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Message-ID: <20260106204801.GA374317@bhelgaas>
Date: Tue, 6 Jan 2026 14:48:01 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc: Atharva Tiwari <atharvatiwarilinuxdev@...il.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Lukas Wunner <lukas@...ner.de>,
	Dave Jiang <dave.jiang@...el.com>,
	Feng Tang <feng.tang@...ux.alibaba.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Andreas Noever <andreas.noever@...il.com>,
	Mika Westerberg <westeri@...nel.org>,
	Yehezkel Bernat <YehezkelShB@...il.com>, linux-usb@...r.kernel.org
Subject: Re: [PATCH] PCI/portdev: Disable AER for Titan Ridge 4C 2018

[+cc Thunderbolt folks]

On Tue, Jan 06, 2026 at 11:00:52AM -0800, Kuppuswamy Sathyanarayanan wrote:
> On 1/6/2026 10:20 AM, Atharva Tiwari wrote:
> > Disable AER for Intel Titan Ridge 4C 2018
> > (used in T2 iMacs, where the warnings appear)
> > that generates continuous pcieport warnings. such as:
> > 
> > pcieport 0000:00:1c.4: AER: Correctable error message received from 0000:07:00.0
> > pcieport 0000:07:00.0: PCIe Bus Error: severity=Correctable, type=Data Link Layer, (Receiver ID)
> > pcieport 0000:07:00.0:   device [8086:15ea] error status/mask=00000080/00002000
> > pcieport 0000:07:00.0:    [ 7] BadDLLP
> > 
> > (see: https://bugzilla.kernel.org/show_bug.cgi?id=220651)
> > 
> > macOS also disables AER for Thunderbolt devices and controllers in
> > their drivers.
> 
> Why not disable it in BIOS or use noaer command line option?

If the kernel can figure this out by itself, we should do that so
users don't have to debug issues and figure out how to disable in BIOS
or use a command line option.

But if this is really a hardware issue, I would expect to see some
reports on the web, and I can't find AER reports that mention these
devices except this problem report.

Adding Thunderbolt folks in case they know about any errata.

> > Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@...il.com>
> > ---
> >  drivers/pci/pcie/portdrv.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
> > index 38a41ccf79b9..5330a679fcff 100644
> > --- a/drivers/pci/pcie/portdrv.c
> > +++ b/drivers/pci/pcie/portdrv.c
> > @@ -240,7 +240,9 @@ static int get_port_device_capability(struct pci_dev *dev)
> >  	if ((pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
> >               pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC) &&
> >  	    dev->aer_cap && pci_aer_available() &&
> > -	    (pcie_ports_native || host->native_aer))
> > +	    (pcie_ports_native || host->native_aer) &&
> > +	    !(dev->vendor == PCI_VENDOR_ID_INTEL &&
> > +		    (dev->device >= 0x15EA && dev->device <= 0x15EC)))
> >  		services |= PCIE_PORT_SERVICE_AER;
> >  #endif
> >  
> 
> -- 
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer
>