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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Wed, 24 Aug 2022 12:20:17 -0500
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Subject: Re: [PATCH v5 2/3] PCI: qcom: Restrict pci transactions after pci suspend
To:     Krishna Chaitanya Chundru <quic_krichai@quicinc.com>,
        helgaas@kernel.org
Cc:     linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, mka@chromium.org,
        quic_vbadigan@quicinc.com, quic_hemantk@quicinc.com,
        quic_nitegupt@quicinc.com, quic_skananth@quicinc.com,
        quic_ramkri@quicinc.com, manivannan.sadhasivam@linaro.org,
        dmitry.baryshkov@linaro.org, Jingoo Han <jingoohan1@gmail.com>,
        Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Rob Herring <robh@kernel.org>,
        =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Stanimir Varbanov <svarbanov@mm-sol.com>
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Quoting Krishna Chaitanya Chundru (2022-08-23 20:37:59)
>
> On 8/9/2022 12:42 AM, Stephen Boyd wrote:
> > Quoting Krishna chaitanya chundru (2022-08-03 04:28:53)
> >> If the endpoint device state is D0 and irq's are not freed, then
> >> kernel try to mask interrupts in system suspend path by writing
> >> in to the vector table (for MSIX interrupts) and config space (for MSI's).
> >>
> >> These transactions are initiated in the pm suspend after pcie clocks got
> >> disabled as part of platform driver pm  suspend call. Due to it, these
> >> transactions are resulting in un-clocked access and eventually to crashes.
> > Why are the platform driver pm suspend calls disabling clks that early?
> > Can they disable clks in noirq phase, or even later, so that we don't
> > have to check if the device is clocking in the irq poking functions?
> > It's best to keep irq operations fast, so that irq control is fast given
> > that these functions are called from irq flow handlers.
>
> We are registering the pcie pm suspend ops as noirq ops only. And this
> msix and config
>
> access is coming at the later point of time that is reason we added that
> check.
>

What is accessing msix and config? Can you dump_stack() after noirq ops
are called and figure out what is trying to access the bus when it is
powered down?