Re: [PATCH v5 2/3] PCI: dwc: Force L2 link entry on shutdown/reboot without D3cold check

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

On 9/9/2026 4:30 PM, Manivannan Sadhasivam wrote:
> On Sat, Sep 05, 2026 at 06:18:49AM +0530, Krishna Chaitanya Chundru wrote:
>> dw_pcie_suspend_noirq() normally calls pci_host_common_d3cold_possible()
>> to check whether every downstream endpoint can be put into D3cold before
>> bothering to move the link to L2. If no endpoint supports it, the
>> function returns early and leaves the link up.
>>
>> Querying D3cold support during shutdown is actively harmful, not just
>> slow: pci_host_common_d3cold_possible() requires every active endpoint
>> to already be in PCI_D3hot, and returns false otherwise. If any endpoint
>> is still in D0 -- which is common, since endpoint drivers aren't
>> guaranteed to have suspended by the time the host's shutdown path runs
>> the check fails and dw_pcie_suspend_noirq() returns early without ever
>> moving the link to L2, leaving it up right up to the point where the
>> system cuts power/clocks to the controller.
>>
>> Add a "force_d3cold" flag to struct dw_pcie_rp that callers set
>> explicitly to force this behavior, rather than having
>> dw_pcie_suspend_noirq() infer the shutdown/reboot case itself from
>> system_state. Still call pci_host_common_d3cold_possible()
>> unconditionally, since it's also how "pme_capable" gets set, but ignore
>> its return value when force_d3cold is set and force L2 entry regardless.
>>
>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
>> ---
>>  drivers/pci/controller/dwc/pcie-designware-host.c | 5 +++--
>>  drivers/pci/controller/dwc/pcie-designware.h      | 1 +
>>  2 files changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
>> index f5a38e6fd8d7..a8a3861c2956 100644
>> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
>> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
>> @@ -1224,14 +1224,15 @@ static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
>>  
>>  int dw_pcie_suspend_noirq(struct dw_pcie *pci)
>>  {
>> -	bool pme_capable = false;
>> +	bool d3cold, pme_capable = false;
>>  	int ret = 0;
>>  	u32 val;
>>  
>>  	if (!dw_pcie_link_up(pci))
>>  		goto stop_link;
>>  
>> -	if (!pci_host_common_d3cold_possible(pci->pp.bridge, &pme_capable))
>> +	d3cold = pci_host_common_d3cold_possible(pci->pp.bridge, &pme_capable);
>> +	if (!d3cold && !pci->pp.force_d3cold)
> I asked for a parameter in dw_pcie_suspend_noirq().
I misinterpreted your comment,  I will do it next series.

- Krishna Chaitanya.
>
> - Mani
>