From: Matthias Kaehlcke <mka@chromium.org>
To: Krishna Kurapati <quic_kriskura@quicinc.com>
Cc: Andy Gross <agross@kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Felipe Balbi <balbi@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Philipp Zabel <p.zabel@pengutronix.de>,
linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] usb: dwc3: qcom: Defer dwc3-qcom probe if dwc3 isn't probed properly
Date: Fri, 15 Jul 2022 13:41:57 -0700 [thread overview]
Message-ID: <YtHRFcol5uslEel1@google.com> (raw)
In-Reply-To: <1657891312-21748-1-git-send-email-quic_kriskura@quicinc.com>
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@quicinc.com>
Reported-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
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.
next prev parent reply other threads:[~2022-07-15 20:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-15 13:21 [PATCH v2] usb: dwc3: qcom: Defer dwc3-qcom probe if dwc3 isn't probed properly Krishna Kurapati
2022-07-15 20:41 ` Matthias Kaehlcke [this message]
2022-07-16 4:13 ` Krishna Kurapati PSSNV
2022-07-27 17:31 ` Matthias Kaehlcke
2022-08-02 16:10 ` Johan Hovold
2022-08-04 4:50 ` Krishna Kurapati PSSNV
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