Re: [PATCH v2 5/5] PCI: qcom: Add D3cold support

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

On 3/5/2026 1:28 PM, Manivannan Sadhasivam wrote:
> On Tue, Feb 17, 2026 at 04:49:10PM +0530, Krishna Chaitanya Chundru wrote:
>> Add support for transitioning Qcom PCIe controllers into D3cold by
> You cannot transition a 'PCIe controller' to D3Cold state, but only the
> endpoints and bridges.
>
>> integrating with the DWC core suspend/resume helpers.
>>
>> Implement PME_TurnOff message generation via ELBI_SYS_CTRL and hook it
>> into the DWC host operations so the controller follows the standard
>> PME_TurnOff-based power-down sequence before entering D3cold.
>>
>> When the link is suspended into D3cold, fully tear down interconnect
> You cannot suspend a link into D3Cold. Link and D-State are different.
>
>> bandwidth, OPP votes. If D3cold is not entered, retain existing behavior
>> by keeping the required interconnect and OPP votes.
>>
>> Drop the qcom_pcie::suspended flag and rely on the existing
>> dw_pcie::suspended state, which now drives both the power-management
>> flow and the interconnect/OPP handling.
>>
>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
>> ---
>>   drivers/pci/controller/dwc/pcie-qcom.c | 121 ++++++++++++++++++++-------------
>>   1 file changed, 74 insertions(+), 47 deletions(-)
>>
>> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
>> index b02c19bbdf2ea5db252c2a0281a569bb3a0cc497..37442bbe588c36b0b0414cc4d0016da2d8424a87 100644
>> --- a/drivers/pci/controller/dwc/pcie-qcom.c
>> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
>> @@ -145,6 +145,7 @@
> [...]
>
>> -	if (pcie->suspended) {
>> -		ret = qcom_pcie_host_init(&pcie->pci->pp);
>> -		if (ret)
>> -			return ret;
>> +		ret = icc_enable(pcie->icc_mem);
>> +		if (ret) {
>> +			dev_err(dev, "Failed to enable PCIe-MEM interconnect path: %d\n", ret);
>> +			goto disable_icc_cpu;
>> +		}
>>   
>> -		pcie->suspended = false;
>> +		/*
>> +		 * Ignore -ETIMEDOUT here since it is expected when no endpoint is
>> +		 * connected to the PCIe link.
>> +		 */
>> +		ret = dw_pcie_resume_noirq(pcie->pci);
>> +		if (ret && (ret != -ETIMEDOUT))
> No, dw_pcie_resume_noirq() was reworked to return -ETIMEDOUT to indicate a hard
> failure. If the device is not found, it will return -ENODEV. So you should
> fail the resume if -ETIMEDOUT is returned.
Ack, didn't noticed the reworked changes, I will change -ETIMEDOUT to 
-ENODEV.

- Krishna Chaitanya.
> - Mani
>