linux-kernel - Re: [PATCH v4] PCI: qcom: Add system PM support

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Date:   Wed, 13 Apr 2022 09:36:30 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     Kalle Valo <kvalo@...nel.org>,
        Prasad Malisetty <quic_pmaliset@...cinc.com>,
        agross@...nel.org, bjorn.andersson@...aro.org,
        lorenzo.pieralisi@....com, robh@...nel.org, kw@...ux.com,
        bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        rajatja@...gle.com, refactormyself@...il.com,
        quic_vbadigan@...cinc.com, quic_ramkri@...cinc.com,
        swboyd@...omium.org, linux-wireless@...r.kernel.org,
        ath11k@...ts.infradead.org
Subject: Re: [PATCH v4] PCI: qcom: Add system PM support

On Wed, 13 Apr 2022 at 08:49, Manivannan Sadhasivam
<manivannan.sadhasivam@...aro.org> wrote:
>
> On Tue, Apr 12, 2022 at 01:40:08PM +0300, Kalle Valo wrote:
> > + ath11k
> >
> > Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org> writes:
> >
> > > +Kalle, linux-wireless
> > >
> > > On Tue, Mar 08, 2022 at 12:25:06AM +0530, Prasad Malisetty wrote:
> > >> Add suspend_noirq and resume_noirq callbacks to handle
> > >> system suspend and resume in dwc PCIe controller driver.
> > >>
> > >> When system suspends, send PME turnoff message to enter
> > >> link into L2 state. Along with powerdown the PHY, disable
> > >> pipe clock, switch gcc_pcie_1_pipe_clk_src to XO if mux is
> > >> supported and disable the pcie clocks, regulators.
> > >>
> > >
> > > Kalle, is this behaviour appropriate for WLAN devices as well? The devices
> > > will be put into poweroff state (assuming no Vaux provided in D3cold) during
> > > system suspend.
> >
> > ath11k leaves the firmware running during suspend. I don't fully
> > understand what the patch is doing, but if it cuts the power from the
> > WLAN chip during suspend that will break ath11k.
> >
>
> Thanks Kalle for the confirmation. Yes the device will be put into D3cold state
> and that will most likely equal to poweroff state.

Just to remind that ath11k on Qualcomm boards has a separate power
supply, not directly tied to the PCIe power supply.

> Prasad, you should try to just turn off the host resources like clocks and
> regulators (not refclk) and let the device be in the default state
> (D3hot/L{0/1}?) during suspend.


-- 
With best wishes
Dmitry