On Fri, Jul 15, 2022 at 01:41:57PM -0700, Matthias Kaehlcke wrote: > On Fri, Jul 15, 2022 at 06:51:52PM +0530, Krishna Kurapati wrote: > > > Subject: usb: dwc3: qcom: Defer dwc3-qcom probe if dwc3 isn't probed properly > > nit: "isn't probed properly" sounds like a bug or HW issue. In case > you re-spin maybe change it to "hasn't probed yet" or similar. > > > 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@xxxxxxxxxxx> > > Reported-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx> > Tested-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx> > Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx> (attempt to 'summarize' and move the discussion from v1 [1] to here) gregkh> Why not limit this check to a device type like your changelog mentions? mka> It is not an sc7180 specific issue. It can occur on any platform where the mka> dwc3 core has supplies that aren't ready when the dwc3-qcom driver probes. mka> mka> It won't blow up right away since it requires 'wakeup-source' to be set for mka> the dwc3 core, which currently is only the case for 'usb@a600000' of the mka> sc7280 AFAIK (I set it for sc7180 in my tree for testing, which is when I mka> found the issue this patch intends to address). krishna> As Mathias pointed out, no issue was seen so far on present QC targets krishna> as wakeup-source property was added recently and only for SC7180 and krishna> SC7280. We ran into some issues like wakeup from system suspend in krishna> host mode wasn't happening although we enabled wakeup-source in SC7180 krishna> that eventually led us to this bug. But, we tried to add debug prints krishna> to follow the code flow and see that the issue is present on SM8350 krishna> as well : "supplier 88e9000.phy-wrapper not ready" and deferring dwc3 krishna> probe. This doesn't seem to be specific to SC7180. krishna> krishna> Since this is seen on multiple platforms, can we go ahead without krishna> having any platforms specific checks in the code as in V2 version ? [1] https://lore.kernel.org/all/YtAv1U1VYkhIY1GA@xxxxxxxxx/t/#m6714bf1f2309cfe8be92e6c270ef2a99a9b09ac6