Messages in this thread | | | Date | Thu, 4 Aug 2022 10:20:20 +0530 | Subject | Re: [PATCH v2] usb: dwc3: qcom: Defer dwc3-qcom probe if dwc3 isn't probed properly | From | Krishna Kurapati PSSNV <> |
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On 8/2/2022 9:40 PM, Johan Hovold wrote: > On Fri, Jul 15, 2022 at 06:51:52PM +0530, Krishna Kurapati wrote: >> On SC7180 devices, it is observed that dwc3 probing is deferred >> because device_links_check_suppliers() finds that '88e3000.phy' >> isn't ready yet. >> >> As a part of its probe call, dwc3-qcom driver checks if dwc3 core >> is wakeup capable or not. If the dwc3 core is wakeup capable, driver >> configures dwc-qcom's power domain to be always ON. Also it configures >> dp/dm interrupts accordingly to support wakeup from system suspend. >> >> More info regarding the same can be found at: >> commit d9be8d5c5b03 ("usb: dwc3: qcom: Keep power domain on to retain controller status") >> commit 6895ea55c385 ("usb: dwc3: qcom: Configure wakeup interrupts during suspend") >> >> In the event, dwc3 probe gets deferred and is processed after dwc3-qcom >> probe, driver ends up reading the wakeup capability of dwc3 core as false >> leading to instability in suspend/resume path. >> >> To avoid this scenario, ensure dwc3_probe is successful by checking >> if appropriate driver is assigned to it or not after the of_platform_populate >> call. If it isn't then defer dwc3-qcom probe as well. >> >> Fixes: 649f5c842ba3 ("usb: dwc3: core: Host wake up support from system suspend") >> Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com> >> --- >> v2: Set return value to EPROBE_DEFER to drop reference to dwc3 node >> >> drivers/usb/dwc3/dwc3-qcom.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c >> index 7703655..6676b39 100644 >> --- a/drivers/usb/dwc3/dwc3-qcom.c >> +++ b/drivers/usb/dwc3/dwc3-qcom.c >> @@ -722,6 +722,9 @@ static int dwc3_qcom_of_register_core(struct platform_device *pdev) >> dev_err(dev, "failed to get dwc3 platform device\n"); >> } >> >> + if (!qcom->dwc3->dev.driver) >> + ret = -EPROBE_DEFER; >> + >> node_put: >> of_node_put(dwc3_np); > NAK. > > We should not be adding hacks like this to the driver. > > There are other ways to avoid this, but please take a look at the > following series which makes the problem identified by this patch go > away first: > > https://lore.kernel.org/all/20220802151404.1797-1-johan+linaro@kernel.org > > Johan Hi Johan,
Thanks for the review and patches. Agreed that if we are moving wakeup-source to glue driver, dwc3 probe getting deferred won't be an issue.
Regards, Krishna,
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