linux-kernel - Re: [PATCH v6 0/5] PCI: qcom: Add system suspend & resume support

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Date:   Wed, 14 Sep 2022 07:17:00 +0530
From:   Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
CC:     <helgaas@...nel.org>, <linux-pci@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <mka@...omium.org>, <quic_vbadigan@...cinc.com>,
        <quic_hemantk@...cinc.com>, <quic_nitegupt@...cinc.com>,
        <quic_skananth@...cinc.com>, <quic_ramkri@...cinc.com>,
        <swboyd@...omium.org>, <dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH v6 0/5] PCI: qcom: Add system suspend & resume support


On 9/12/2022 11:07 PM, Manivannan Sadhasivam wrote:
> On Fri, Sep 09, 2022 at 02:14:39PM +0530, Krishna chaitanya chundru wrote:
>> Add suspend and resume syscore ops.
>>
>> When system suspends, and if the link is in L1ss, disable the clocks
>> and power down the phy so that system enters into low power state by
>> parking link in L1ss to save the maximum power. And when the system
>> resumes, enable the clocks back and power on phy if they are disabled
>> in the suspend path.
>>
> You need to mention that you are only turning off the PCIe controller
> clocks and PHY is still powered by a separate domain (MX) so the link
> statys intact.
sure I will update the commit in next series.
>> we are doing this only when link is in l1ss but not in L2/L3 as
>> nowhere we are forcing link to L2/L3 by sending PME turn off.
>>
>> is_suspended flag indicates if the clocks are disabled in the suspend
>> path or not.
>>
>> There is access to Ep PCIe space to mask MSI/MSIX after pm suspend ops
>> (getting hit by affinity changes while making CPUs offline during suspend,
>> this will happen after devices are suspended (all phases of suspend ops)).
>> When registered with pm ops there is a crash due to un-clocked access,
>> as in the pm suspend op clocks are disabled. So, registering with syscore
>> ops which will called after making CPUs offline.
>>
>> Make GDSC always on to ensure controller and its dependent clocks
>> won't go down during system suspend.
>>
> Where is the changelog? You seem to have added PHY and CLK patches to
> this series. You need to comment on that.
>
> Thanks,
> Mani
I will update that in next patch.
>> Krishna chaitanya chundru (5):
>>    PCI: qcom: Add system suspend and resume support
>>    PCI: qcom: Add retry logic for link to be stable in L1ss
>>    phy: core: Add support for phy power down & power up
>>    phy: qcom: Add power down/up callbacks to pcie phy
>>    clk: qcom: Alwaya on pcie gdsc
>>
>>   drivers/clk/qcom/gcc-sc7280.c            |   2 +-
>>   drivers/pci/controller/dwc/pcie-qcom.c   | 156 ++++++++++++++++++++++++++++++-
>>   drivers/phy/phy-core.c                   |  30 ++++++
>>   drivers/phy/qualcomm/phy-qcom-qmp-pcie.c |  50 ++++++++++
>>   include/linux/phy/phy.h                  |  20 ++++
>>   5 files changed, 256 insertions(+), 2 deletions(-)
>>
>> -- 
>> 2.7.4
>>