Re: [PATCH v6 0/3] PCI: qcom: Implement shutdown() to avoid SMMU/NoC errors on reboot

[Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>]

On 9/9/2026 6:08 PM, Konrad Dybcio wrote:
> On 9/9/26 2:24 PM, Krishna Chaitanya Chundru wrote:
>> During system shutdown/reboot, power/clocks to the PCIe controller get
>> removed regardless of link state. If the link is still up when that
>> happens, it can trigger SMMU or NoC errors.
>>
>> This series adds a shutdown() callback to the Qualcomm PCIe host driver
>> that forces the link into L2/D3cold before shutdown proceeds, reusing
>> the existing suspend_noirq() path.
>>
>> Patch 1 fixes pci_host_common_d3cold_possible()'s underlying bus walk,
>> which aborts as soon as it finds a device outside D3hot and can
>> therefore miss a later PME-capable device -- something that becomes
>> common once patch 3 starts forcing D3cold entry during shutdown while
>> endpoints may still be in D0.
>>
>> Patch 2 adds a force parameter to  dw_pcie_suspend_noirq() so that callers can
>> set to make dw_pcie_suspend_noirq() force L2 entry during shutdown/
>> reboot, skipping the D3cold capability check that can otherwise leave
>> the link up if any endpoint hasn't suspended yet.
>>
>> Patch 3 adds qcom_pcie_shutdown() and wires it up as .shutdown.
>>
>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
>> ---
>> Changes in v6:
>> - remove return 0 in d3cold_possible() (konrad)
> I re-read it once again and I'm not sure my comment was right..
If we return directly without checking the pme capability we might disable
power to the endpoint and wake up may be broken.
I taught you pointed that mistake only. we need to check pme capability even
when device is not in d3hot.

- Krishna Chaitanya.
>
> Konrad