Messages in this thread | | | Date | Wed, 15 Jun 2022 01:07:01 +0530 | Subject | Re: [PATCH v20 2/5] usb: dwc3: core: Host wake up support from system suspend | From | Krishna Kurapati PSSNV <> |
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On 6/14/2022 11:23 PM, Matthias Kaehlcke wrote: > On Mon, Jun 13, 2022 at 11:08:32AM -0700, Matthias Kaehlcke wrote: >> On Mon, Jun 06, 2022 at 01:45:51PM -0700, Matthias Kaehlcke wrote: >>> On Thu, Jun 02, 2022 at 12:35:42PM -0700, Matthias Kaehlcke wrote: >>>> Hi Krishna, >>>> >>>> with this version I see xHCI errors on my SC7180 based system, like >>>> these: >>>> >>>> [ 65.352605] xhci-hcd xhci-hcd.13.auto: xHC error in resume, USBSTS 0x401, Reinit >>>> >>>> [ 101.307155] xhci-hcd xhci-hcd.13.auto: WARN: xHC CMD_RUN timeout >>>> >>>> After resume a downstream hub isn't enumerated again. >>>> >>>> So far I didn't see those with v13, but I aso saw the first error with >>>> v16. >>> It also happens with v13, but only when a wakeup capable vUSB <= 2 >>> device is plugged in. Initially I used a wakeup capable USB3 to >>> Ethernet adapter to trigger the wakeup case, however older versions >>> of this series that use usb_wakeup_enabled_descendants() to check >>> for wakeup capable devices didn't actually check for vUSB > 2 >>> devices. >>> >>> So the case were the controller/PHYs is powered down works, but >>> the controller is unhappy when the runtime PM path is used during >>> system suspend. >> The issue isn't seen on all systems using dwc3-qcom and the problem starts >> during probe(). The expected probe sequence is something like this: >> >> dwc3_qcom_probe >> dwc3_qcom_of_register_core >> dwc3_probe >> >> if (device_can_wakeup(&qcom->dwc3->dev)) >> ... >> >> The important part is that device_can_wakeup() is called after dwc3_probe() >> has completed. That's what I see on a QC SC7280 system, where wakeup is >> generally working with these patches. >> >> However on a QC SC7180 system dwc3_probe() is deferred and only executed after >> dwc3_qcom_probe(). As a result the device_can_wakeup() call returns false. >> With that the controller/driver ends up in an unhappy state after system >> suspend. >> >> Probing is deferred on SC7180 because device_links_check_suppliers() finds >> that '88e3000.phy' isn't ready yet. > It seems device links could be used to make sure the dwc3 core is present: > > Another example for an inconsistent state would be a device link that > represents a driver presence dependency, yet is added from the consumer’s > ->probe callback while the supplier hasn’t probed yet: Had the driver core > known about the device link earlier, it wouldn’t have probed the consumer > in the first place. The onus is thus on the consumer to check presence of > the supplier after adding the link, and defer probing on non-presence. > > https://www.kernel.org/doc/html/v5.18/driver-api/device_link.html#usage > > > You could add something like this to dwc3_qcom_of_register_core(): > > > device_link_add(dev, &qcom->dwc3->dev, > DL_FLAG_AUTOREMOVE_CONSUMER | DL_FLAG_AUTOPROBE_CONSUMER); > > if (qcom->dwc3->dev.links.status != DL_DEV_DRIVER_BOUND) > ret = -EPROBE_DEFER; > > > From the doc it isn't clear how the consumer is supposed to check presence > of the supplier, the above check of the link status is also used in > drivers/cpufreq/mediatek-cpufreq.c , but not elsewhere outside of the > driver framework. Hi Mathias,
Thanks for the input. I will try the above snippet and confirm if probe call happens in sync with of_platform_populate in dwc3_qcom_of_register_core
Regards, Krishna,
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