Re: [PATCH v2 5/7] usb: dwc3: add xhci-reset-on-resume property for power-loss resume

[Faisal Hassan <faisal.hassan@oss.qualcomm.com>]

On 04-09-2026 11:39 am, Krishna Kurapati wrote:
>
>
> On 9/3/2026 9:08 PM, Faisal Hassan wrote:
>> On platforms where the USB controller loses power during system
>> suspend, like SA8255P, resume triggers a Host Controller Error
>> requiring full reinitialization.
>>
>> The xhci driver supports XHCI_RESET_ON_RESUME to handle this,
>> but dwc3 previously lacked platform-specific quirk configuration.
>> Add a device property "xhci-reset-on-resume" that enables this
>> quirk for controllers needing complete reinitialization after
>> power loss during suspend.
>>
>> Let dwc3 manage the quirk for the usb controller using
>> software properties.
>>
>> Co-developed-by: Sriram Dash <sriram.dash@oss.qualcomm.com>
>> Signed-off-by: Sriram Dash <sriram.dash@oss.qualcomm.com>
>> Signed-off-by: Faisal Hassan <faisal.hassan@oss.qualcomm.com>
>> ---
>>   drivers/usb/dwc3/core.c | 4 ++++
>>   drivers/usb/dwc3/core.h | 5 +++++
>>   drivers/usb/dwc3/host.c | 5 ++++-
>>   3 files changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index fd5c2cd36c59..eb6ffd5148a7 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1712,6 +1712,10 @@ static void 
>> dwc3_get_software_properties(struct dwc3 *dwc,
>>                              &gsbuscfg0_reqinfo);
>>           if (!ret)
>>               dwc->gsbuscfg0_reqinfo = gsbuscfg0_reqinfo;
>> +
>> +        if (!dwc->xhci_reset_on_resume &&
>> +            device_property_read_bool(tmpdev, "xhci-reset-on-resume"))
>> +            dwc->xhci_reset_on_resume = true;
>>       }
>
> xHCI plat does look for properties in xhci device node as well as the 
> ones above it in the parent chain:
>
> "
>     /* Iterate over all parent nodes for finding quirks */
>     for (tmpdev = &pdev->dev; tmpdev; tmpdev = tmpdev->parent) {
> "
>
> So adding device_add_software_node in dwc3_qcom must be sufficient.
>
> Regards,
> Krishna,


Good catch, you're right. Since xhci-plat already walks the parent
chain, there's no need to round-trip this through dwc3 core. I'm
dropping this patch and attaching the software node on dwc3-qcom's own
device instead, in the "Support broken suspend for SA8255P" patch later
in the series.

Thanks,
Faisal