APPLIED [OEM-5.6] Re: [PATCH 0/1][SRU][OEM-5.6/G] UBUNTU: SAUCE: PCI/ASPM: VMD: add ASPM quirk for 8086:a0bc

[You-Sheng Yang]

On 2020-09-01 18:43, Timo Aaltonen wrote:
> On 31.8.2020 12.35, You-Sheng Yang wrote:
>> BugLink: https://bugs.launchpad.net/bugs/1893194
>>
>> [Impact]
>>
>> One VMD equipped platform has another PCI bridge with PCI ID [8086:a0bc]
>> that is not already in Ubuntu sauced PCI_DEV_FLAGS_ENABLE_ASPM list from
>> bug 1889384. Link Capability Register shows ASPM L1 supported, but has
>> ASPM Disabled in Link Control status.
>>
>> 10000:e0:1c.4 PCI bridge [0604]: Intel Corporation Device [8086:a0bc]
>> (rev 20) (prog-if 00 [Normal decode])
>>         ...
>>  Capabilities: [40] Express (v2) Root Port (Slot+), MSI 00
>>   ...
>>   LnkCap: Port #5, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L1 <16us
>>    ClockPM- Surprise- LLActRep+ BwNot+ ASPMOptComp+
>>   LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
>>    ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
>>
>> [Fix]
>>
>> Add 8086:a0bc to PCI_DEV_FLAGS_ENABLE_ASPM quirk list introduced in Bug
>> 1889384. The proposed fix for Bug 1889384 is still under review on
>> linux-pci mailing list
>> https://lore.kernel.org/linux-pci/20200821123222.32093-1-kai.heng.feng@canonical.com/.
>>
>> [Test Case]
>>
>> Use `sudo lspci -vvnnxxx` to check LnkCap/LnkCtl registers. Make sure it
>> becomes:
>>
>>   LnkCtl: ASPM Enabled, ...
>>
>> [Regression Potential]
>>
>> Low. Like the previous fix in bug 1889384, this add the device ID who
>> declaring capable of link ASPM support to the quirk list.
>>
>> You-Sheng Yang (1):
>>   UBUNTU: SAUCE: PCI/ASPM: VMD: add ASPM quirk for 8086:a0bc
>>
>>  drivers/pci/quirks.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
> 
> applied to oem-5.6, but shouldn't this go upstream as well?

Yes, but while the core parts is still in debate in linux-pci, I think
we can either add this to the next revision of Kai-Heng's patch along
with another [8086:a0b0], which is also only available in Ubuntu oem
kernel tree, or as a an independent thread (also with [8086:a0b0]) if
Kai-Heng's patch just gets merged as is.

You-Sheng Yang

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