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

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Kalle Valo <kvalo@kernel.org>,
	Prasad Malisetty <quic_pmaliset@quicinc.com>,
	agross@kernel.org, bjorn.andersson@linaro.org,
	lorenzo.pieralisi@arm.com, robh@kernel.org, kw@linux.com,
	bhelgaas@google.com, linux-pci@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	rajatja@google.com, refactormyself@gmail.com,
	quic_vbadigan@quicinc.com, quic_ramkri@quicinc.com,
	swboyd@chromium.org, linux-wireless@vger.kernel.org,
	ath11k@lists.infradead.org
Subject: Re: [PATCH v4] PCI: qcom: Add system PM support
Date: Wed, 13 Apr 2022 12:35:42 +0530	[thread overview]
Message-ID: <20220413070542.GB2015@thinkpad> (raw)
In-Reply-To: <CAA8EJprcQtVFvjL_WsMoDxvPSAqaRMS90ZuTsD_cDuujtr83Xw@mail.gmail.com>

On Wed, Apr 13, 2022 at 09:36:30AM +0300, Dmitry Baryshkov wrote:
> On Wed, 13 Apr 2022 at 08:49, Manivannan Sadhasivam
> <manivannan.sadhasivam@linaro.org> wrote:
> >
> > On Tue, Apr 12, 2022 at 01:40:08PM +0300, Kalle Valo wrote:
> > > + ath11k
> > >
> > > Manivannan Sadhasivam <manivannan.sadhasivam@linaro.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.
> 

It may change in the future or on a different OEM setup. Irrespective of that,
this patch sends the PME_Turn_Off event to the ep devices. The devices in turn
will shutdown the internal resources for poweroff/refclk removal. Therefore the
device state shall be lost.

Thanks,
Mani

> > 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