Re: [PATCH v2] usb: dwc3: qcom: Defer dwc3-qcom probe if dwc3 isn't probed properly
From: Krishna Kurapati PSSNV
Date: Sat Jul 16 2022 - 00:13:45 EST
On 7/16/2022 2:11 AM, 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>
Please make sure to add reviewers of previous versions or other folks you
would like to review your patches in cc. I found v2 accidentally while
looking for something else.
Hi Mathias,
Sure, Thanks for the review.