Re: [PATCH 2/3] USB: dwc3: qcom: fix wakeup after probe deferral

From: Krishna Kurapati PSSNV
Date: Tue Nov 21 2023 - 09:08:45 EST


Just one query. Even if it wakes up after closing the lid and removing
the mouse, wouldn't pm suspend be triggered again later by the system
once it sees that usb is also good to be suspended again ? I presume a
laptop form factor would be having this facility of re-trigerring
suspend. Let me know if this is not the case.

No, we generally don't use opportunistic suspend (e.g. unlike android)
so the laptop will not suspend again.

So this is an actual bug affecting, for example, the Lenovo ThinkPad
X13s.

Thanks for the clarification. I was thinking in android perspective only. But if we don't wake up the system upon disconnect, wouldn't the controller still be under the assumption that device is connected when it is actually not and only realise this when we resume later ?

Also, the warning you are mentioning in [1] comes because this is a
laptop form factor and we have some firmware running (I don't know much
about ACPI and stuff) ?

No, the "firmware" in this case is just the devicetree which has the
DP/DM interrupts defined as edge-triggered while the driver requests
them as level triggered.

(It would look similar with ACPI firmware which also has these declared
as edge triggered.)

Got it. Thanks for the clarification.

Regards,
Krishna,