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

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Message-ID: <749cf4e3-ce0d-4620-8c4f-dea1c9fb85e7@linux.intel.com>
Date: Tue, 6 Jan 2026 11:54:31 -0800
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Atharva Tiwari <atharvatiwarilinuxdev@...il.com>
Cc: 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
Subject: Re: [PATCH] PCI/portdev: Disable AER for Titan Ridge 4C 2018



On 1/6/2026 11:00 AM, 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?

As per the bugzilla report, this looks like a regression. Did you bisect
to find which commit introduced this warning?

Before disabling AER, please investigate the root cause:

Does this occur on all T2 iMacs or specific configurations?
Have you tested different PCIe link speeds?
Is this a cable/connection issue or firmware problem?

The device range (0x15EA-0x15EC) needs justification. Which specific
Titan Ridge variants have this issue?

Before fixing it, try to identify the root cause.

If it needs kernel fix, you need to use quirks (since BIOS
change does not work for you).

> 
>> 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