Date:   Tue, 30 Aug 2022 13:15:54 +0200
From:   Lukasz Majczak <lma@...ihalf.com>
To:     Vidya Sagar <vidyas@...dia.com>
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Rajat Jain <rajatja@...gle.com>,
        Ben Chuang <benchuanggli@...il.com>, bhelgaas@...gle.com,
        lorenzo.pieralisi@....com, refactormyself@...il.com, kw@...ux.com,
        kenny@...ix.com, treding@...dia.com, jonathanh@...dia.com,
        abhsahu@...dia.com, sagupta@...dia.com, linux-pci@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        kthota@...dia.com, mmaddireddy@...dia.com, sagar.tv@...il.com
Subject: Re: [PATCH V2] PCI/ASPM: Save/restore L1SS Capability for suspend/resume

pt., 26 sie 2022 o 15:00 Vidya Sagar <vidyas@...dia.com> napisał(a):
>
>
>
> On 8/23/2022 8:25 PM, Kai-Heng Feng wrote:
> > External email: Use caution opening links or attachments
> >
> >
> > Hi Vidya,
> >
> > On Tue, Aug 9, 2022 at 12:17 AM Vidya Sagar <vidyas@...dia.com> wrote:
> >>
> >> Thanks Lukasz for the update.
> >> I think confirms that there is no issue with the patch as such.
> >> Bjorn, could you please define the next step for this patch?
> >
> > I think the L1SS cap went away _after_ L1SS registers are restored,
> > since your patch already check the cap before doing any write:
> > +       aspm_l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
> > +       if (!aspm_l1ss)
> > +               return;
> >
> > That means it's more likely to be caused by the following change:
> > +       pci_write_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL2, *cap++);
> > +       pci_write_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL1, *cap++);
> >
> > So is it possible to clear PCI_L1SS_CTL1 before setting PCI_L1SS_CTL2,
> > like what aspm_calc_l1ss_info() does?
>
> I posted a new patch
> https://patchwork.kernel.org/project/linux-pci/patch/20220826125526.28859-1-vidyas@nvidia.com/
> keeping L1.2 disabled while restoring the rest of the fields in
> Control-1 register and restoring the L1.2 enable bits later. Could you
> please try this new patch on your setup and update your observations?
>
> Thanks & Regards,
> Vidya Sagar
>
> >
> > Kai-Heng
> >
> >>
> >> Thanks,
> >> Vidya Sagar
> >>
> >> On 8/8/2022 7:37 PM, Lukasz Majczak wrote:
> >>> External email: Use caution opening links or attachments
> >>>
> >>>
> >>> śr., 3 sie 2022 o 14:55 Vidya Sagar <vidyas@...dia.com> napisał(a):
> >>>>
> >>>> Thanks Lukasz for the logs.
> >>>> I still that the L1SS capability in the root port (00:14.0) disappeared
> >>>> after resume.
> >>>> I still don't understand how this patch can make the capability register
> >>>> itself disappear. Honestly, I still see this as a HW issue.
> >>>> Bjorn, could you please throw some light on this?
> >>>>
> >>>> Thanks,
> >>>> Vidya Sagar
> >>>>
> >>>> On 8/3/2022 5:34 PM, Lukasz Majczak wrote:
> >>>>> External email: Use caution opening links or attachments
> >>>>>
> >>>>>
> >>>>> pt., 29 lip 2022 o 16:36 Vidya Sagar <vidyas@...dia.com> napisał(a):
> >>>>>>
> >>>>>> Hi Lukasz,
> >>>>>> Thanks for sharing your observations.
> >>>>>>
> >>>>>> Could you please also share the output of 'sudo lspci -vvvv' before and
> >>>>>> after suspend-resume cycle with the latest linux-next?
> >>>>>> Do we still see the L1SS capabilities getting disappeared post resume?
> >>>>>>
> >>>>>> Thanks,
> >>>>>> Vidya Sagar
> >>>>>>
> >>>>>> On 7/29/2022 3:09 PM, Lukasz Majczak wrote:
> >>>>>>> External email: Use caution opening links or attachments
> >>>>>>>
> >>>>>>>
> >>>>>>> wt., 26 lip 2022 o 09:20 Lukasz Majczak <lma@...ihalf.com> napisał(a):
> >>>>>>>>
> >>>>>>>> wt., 26 lip 2022 o 00:51 Rajat Jain <rajatja@...gle.com> napisał(a):
> >>>>>>>>>
> >>>>>>>>> Hello,
> >>>>>>>>>
> >>>>>>>>> On Sat, Jul 23, 2022 at 10:03 AM Vidya Sagar <vidyas@...dia.com> wrote:
> >>>>>>>>>>
> >>>>>>>>>> Agree with Bjorn's observations.
> >>>>>>>>>> The fact that the L1SS capability registers themselves disappeared in
> >>>>>>>>>> the root port post resume indicates that there seems to be something
> >>>>>>>>>> wrong with the BIOS itself.
> >>>>>>>>>> Could you please check from that perspective?
> >>>>>>>>>
> >>>>>>>>> ChromeOS Intel platforms use S0ix (suspend-to-idle) for suspend. This
> >>>>>>>>> is a shallower sleep state that preserves more state than, for e.g. S3
> >>>>>>>>> (suspend-to-RAM). When we use S0ix, then BIOS does not come in picture
> >>>>>>>>> at all. i.e. after the kernel runs its suspend routines, it just puts
> >>>>>>>>> the CPU into S0ix state. So I do not think there is a BIOS angle to
> >>>>>>>>> this.
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> Thanks,
> >>>>>>>>>> Vidya Sagar
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> On 7/22/2022 11:12 PM, Bjorn Helgaas wrote:
> >>>>>>>>>>> External email: Use caution opening links or attachments
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> On Fri, Jul 22, 2022 at 11:41:14AM +0200, Lukasz Majczak wrote:
> >>>>>>>>>>>> pt., 22 lip 2022 o 09:31 Kai-Heng Feng <kai.heng.feng@...onical.com> napisał(a):
> >>>>>>>>>>>>> On Fri, Jul 15, 2022 at 6:38 PM Ben Chuang <benchuanggli@...il.com> wrote:
> >>>>>>>>>>>>>> On Tue, Jul 5, 2022 at 2:00 PM Vidya Sagar <vidyas@...dia.com> wrote:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Previously ASPM L1 Substates control registers (CTL1 and CTL2) weren't
> >>>>>>>>>>>>>>> saved and restored during suspend/resume leading to L1 Substates
> >>>>>>>>>>>>>>> configuration being lost post-resume.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Save the L1 Substates control registers so that the configuration is
> >>>>>>>>>>>>>>> retained post-resume.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
> >>>>>>>>>>>>>>> Tested-by: Abhishek Sahu <abhsahu@...dia.com>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Hi Vidya,
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> I tested this patch on kernel v5.19-rc6.
> >>>>>>>>>>>>>> The test device is GL9755 card reader controller on Intel i5-10210U RVP.
> >>>>>>>>>>>>>> This patch can restore L1SS after suspend/resume.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> The test results are as follows:
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> After Boot:
> >>>>>>>>>>>>>> #lspci -d 17a0:9755 -vvv | grep -A5 "L1 PM Substates"
> >>>>>>>>>>>>>>              Capabilities: [110 v1] L1 PM Substates
> >>>>>>>>>>>>>>                      L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+
> >>>>>>>>>>>>>> ASPM_L1.1+ L1_PM_Substates+
> >>>>>>>>>>>>>>                                PortCommonModeRestoreTime=255us
> >>>>>>>>>>>>>> PortTPowerOnTime=3100us
> >>>>>>>>>>>>>>                      L1SubCtl1: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+
> >>>>>>>>>>>>>>                                 T_CommonMode=0us LTR1.2_Threshold=3145728ns
> >>>>>>>>>>>>>>                      L1SubCtl2: T_PwrOn=3100us
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> After suspend/resume without this patch.
> >>>>>>>>>>>>>> #lspci -d 17a0:9755 -vvv | grep -A5 "L1 PM Substates"
> >>>>>>>>>>>>>>              Capabilities: [110 v1] L1 PM Substates
> >>>>>>>>>>>>>>                      L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+
> >>>>>>>>>>>>>> ASPM_L1.1+ L1_PM_Substates+
> >>>>>>>>>>>>>>                                PortCommonModeRestoreTime=255us
> >>>>>>>>>>>>>> PortTPowerOnTime=3100us
> >>>>>>>>>>>>>>                      L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
> >>>>>>>>>>>>>>                                 T_CommonMode=0us LTR1.2_Threshold=0ns
> >>>>>>>>>>>>>>                      L1SubCtl2: T_PwrOn=10us
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> After suspend/resume with this patch.
> >>>>>>>>>>>>>> #lspci -d 17a0:9755 -vvv | grep -A5 "L1 PM Substates"
> >>>>>>>>>>>>>>              Capabilities: [110 v1] L1 PM Substates
> >>>>>>>>>>>>>>                      L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+
> >>>>>>>>>>>>>> ASPM_L1.1+ L1_PM_Substates+
> >>>>>>>>>>>>>>                                PortCommonModeRestoreTime=255us
> >>>>>>>>>>>>>> PortTPowerOnTime=3100us
> >>>>>>>>>>>>>>                      L1SubCtl1: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+
> >>>>>>>>>>>>>>                                 T_CommonMode=0us LTR1.2_Threshold=3145728ns
> >>>>>>>>>>>>>>                      L1SubCtl2: T_PwrOn=3100us
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Tested-by: Ben Chuang <benchuanggli@...il.com>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Forgot to add mine:
> >>>>>>>>>>>>> Tested-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Best regards,
> >>>>>>>>>>>>>> Ben Chuang
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> ---
> >>>>>>>>>>>>>>> Hi,
> >>>>>>>>>>>>>>> Kenneth R. Crudup <kenny@...ix.com>, Could you please verify this patch
> >>>>>>>>>>>>>>> on your laptop (Dell XPS 13) one last time?
> >>>>>>>>>>>>>>> IMHO, the regression observed on your laptop with an old version of the patch
> >>>>>>>>>>>>>>> could be due to a buggy old version BIOS in the laptop.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Thanks,
> >>>>>>>>>>>>>>> Vidya Sagar
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>       drivers/pci/pci.c       |  7 +++++++
> >>>>>>>>>>>>>>>       drivers/pci/pci.h       |  4 ++++
> >>>>>>>>>>>>>>>       drivers/pci/pcie/aspm.c | 44 +++++++++++++++++++++++++++++++++++++++++
> >>>>>>>>>>>>>>>       3 files changed, 55 insertions(+)
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> >>>>>>>>>>>>>>> index cfaf40a540a8..aca05880aaa3 100644
> >>>>>>>>>>>>>>> --- a/drivers/pci/pci.c
> >>>>>>>>>>>>>>> +++ b/drivers/pci/pci.c
> >>>>>>>>>>>>>>> @@ -1667,6 +1667,7 @@ int pci_save_state(struct pci_dev *dev)
> >>>>>>>>>>>>>>>                      return i;
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>              pci_save_ltr_state(dev);
> >>>>>>>>>>>>>>> +       pci_save_aspm_l1ss_state(dev);
> >>>>>>>>>>>>>>>              pci_save_dpc_state(dev);
> >>>>>>>>>>>>>>>              pci_save_aer_state(dev);
> >>>>>>>>>>>>>>>              pci_save_ptm_state(dev);
> >>>>>>>>>>>>>>> @@ -1773,6 +1774,7 @@ void pci_restore_state(struct pci_dev *dev)
> >>>>>>>>>>>>>>>               * LTR itself (in the PCIe capability).
> >>>>>>>>>>>>>>>               */
> >>>>>>>>>>>>>>>              pci_restore_ltr_state(dev);
> >>>>>>>>>>>>>>> +       pci_restore_aspm_l1ss_state(dev);
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>              pci_restore_pcie_state(dev);
> >>>>>>>>>>>>>>>              pci_restore_pasid_state(dev);
> >>>>>>>>>>>>>>> @@ -3489,6 +3491,11 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev)
> >>>>>>>>>>>>>>>              if (error)
> >>>>>>>>>>>>>>>                      pci_err(dev, "unable to allocate suspend buffer for LTR\n");
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> +       error = pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_L1SS,
> >>>>>>>>>>>>>>> +                                           2 * sizeof(u32));
> >>>>>>>>>>>>>>> +       if (error)
> >>>>>>>>>>>>>>> +               pci_err(dev, "unable to allocate suspend buffer for ASPM-L1SS\n");
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>>              pci_allocate_vc_save_buffers(dev);
> >>>>>>>>>>>>>>>       }
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> >>>>>>>>>>>>>>> index e10cdec6c56e..92d8c92662a4 100644
> >>>>>>>>>>>>>>> --- a/drivers/pci/pci.h
> >>>>>>>>>>>>>>> +++ b/drivers/pci/pci.h
> >>>>>>>>>>>>>>> @@ -562,11 +562,15 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev);
> >>>>>>>>>>>>>>>       void pcie_aspm_exit_link_state(struct pci_dev *pdev);
> >>>>>>>>>>>>>>>       void pcie_aspm_pm_state_change(struct pci_dev *pdev);
> >>>>>>>>>>>>>>>       void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
> >>>>>>>>>>>>>>> +void pci_save_aspm_l1ss_state(struct pci_dev *dev);
> >>>>>>>>>>>>>>> +void pci_restore_aspm_l1ss_state(struct pci_dev *dev);
> >>>>>>>>>>>>>>>       #else
> >>>>>>>>>>>>>>>       static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { }
> >>>>>>>>>>>>>>>       static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { }
> >>>>>>>>>>>>>>>       static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev) { }
> >>>>>>>>>>>>>>>       static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { }
> >>>>>>>>>>>>>>> +static inline void pci_save_aspm_l1ss_state(struct pci_dev *dev) { }
> >>>>>>>>>>>>>>> +static inline void pci_restore_aspm_l1ss_state(struct pci_dev *dev) { }
> >>>>>>>>>>>>>>>       #endif
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>       #ifdef CONFIG_PCIE_ECRC
> >>>>>>>>>>>>>>> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> >>>>>>>>>>>>>>> index a96b7424c9bc..2c29fdd20059 100644
> >>>>>>>>>>>>>>> --- a/drivers/pci/pcie/aspm.c
> >>>>>>>>>>>>>>> +++ b/drivers/pci/pcie/aspm.c
> >>>>>>>>>>>>>>> @@ -726,6 +726,50 @@ static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
> >>>>>>>>>>>>>>>                                      PCI_L1SS_CTL1_L1SS_MASK, val);
> >>>>>>>>>>>>>>>       }
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> +void pci_save_aspm_l1ss_state(struct pci_dev *dev)
> >>>>>>>>>>>>>>> +{
> >>>>>>>>>>>>>>> +       int aspm_l1ss;
> >>>>>>>>>>>>>>> +       struct pci_cap_saved_state *save_state;
> >>>>>>>>>>>>>>> +       u32 *cap;
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +       if (!pci_is_pcie(dev))
> >>>>>>>>>>>>>>> +               return;
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +       aspm_l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
> >>>>>>>>>>>>>>> +       if (!aspm_l1ss)
> >>>>>>>>>>>>>>> +               return;
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +       save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS);
> >>>>>>>>>>>>>>> +       if (!save_state)
> >>>>>>>>>>>>>>> +               return;
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +       cap = (u32 *)&save_state->cap.data[0];
> >>>>>>>>>>>>>>> +       pci_read_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL2, cap++);
> >>>>>>>>>>>>>>> +       pci_read_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL1, cap++);
> >>>>>>>>>>>>>>> +}
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +void pci_restore_aspm_l1ss_state(struct pci_dev *dev)
> >>>>>>>>>>>>>>> +{
> >>>>>>>>>>>>>>> +       int aspm_l1ss;
> >>>>>>>>>>>>>>> +       struct pci_cap_saved_state *save_state;
> >>>>>>>>>>>>>>> +       u32 *cap;
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +       if (!pci_is_pcie(dev))
> >>>>>>>>>>>>>>> +               return;
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +       aspm_l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
> >>>>>>>>>>>>>>> +       if (!aspm_l1ss)
> >>>>>>>>>>>>>>> +               return;
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +       save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS);
> >>>>>>>>>>>>>>> +       if (!save_state)
> >>>>>>>>>>>>>>> +               return;
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>> +       cap = (u32 *)&save_state->cap.data[0];
> >>>>>>>>>>>>>>> +       pci_write_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL2, *cap++);
> >>>>>>>>>>>>>>> +       pci_write_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL1, *cap++);
> >>>>>>>>>>>>>>> +}
> >>>>>>>>>>>>>>> +
> >>>>>>>>>>>>>>>       static void pcie_config_aspm_dev(struct pci_dev *pdev, u32 val)
> >>>>>>>>>>>>>>>       {
> >>>>>>>>>>>>>>>              pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
> >>>>>>>>>>>>>>> --
> >>>>>>>>>>>>>>> 2.17.1
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>> Hi,
> >>>>>>>>>>>>
> >>>>>>>>>>>> With this patch (and also mentioned
> >>>>>>>>>>>> https://lore.kernel.org/all/20220509073639.2048236-1-kai.heng.feng@canonical.com/)
> >>>>>>>>>>>> applied on 5.10 (chromeos-5.10) I am observing problems after
> >>>>>>>>>>>> suspend/resume with my WiFi card - it looks like whole communication
> >>>>>>>>>>>> via PCI fails. Attaching logs (dmesg, lspci -vvv before suspend/resume
> >>>>>>>>>>>> and after) https://gist.github.com/semihalf-majczak-lukasz/fb36dfa2eff22911109dfb91ab0fc0e3
> >>>>>>>>>>>>
> >>>>>>>>>>>> I played a little bit with this code and it looks like the
> >>>>>>>>>>>> pci_write_config_dword() to the PCI_L1SS_CTL1 breaks it (don't know
> >>>>>>>>>>>> why, not a PCI expert).
> >>>>>>>>>>>
> >>>>>>>>>>> Thanks a lot for testing this!  I'm not quite sure what to make of the
> >>>>>>>>>>> results since v5.10 is fairly old (Dec 2020) and I don't know what
> >>>>>>>>>>> other changes are in chromeos-5.10.
> >>>>>>>>>
> >>>>>>>>> Lukasz: I assume you are running this on Atlas and are seeing this bug
> >>>>>>>>> when uprev'ving it to 5.10 kernel. Can you please try it on a newer
> >>>>>>>>> Intel platform that have the latest upstream kernel running already
> >>>>>>>>> and see if this can be reproduced there too?
> >>>>>>>>> Note that the wifi PCI device is different on newer Intel platforms,
> >>>>>>>>> but platform design is similar enough that I suspect we should see
> >>>>>>>>> similar bug on those too. The other option is to try the latest
> >>>>>>>>> ustream kernel on Atlas. Perhaps if we just care about wifi (and
> >>>>>>>>> ignore bringing up the graphics stack and GUI), it may come up
> >>>>>>>>> sufficiently enough to try this patch?
> >>>>>>>>>
> >>>>>>>>> Thanks,
> >>>>>>>>>
> >>>>>>>>> Rajat
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> Random observations, no analysis below.  This from your dmesg
> >>>>>>>>>>> certainly looks like PCI reads failing and returning ~0:
> >>>>>>>>>>>
> >>>>>>>>>>>        Timeout waiting for hardware access (CSR_GP_CNTRL 0xffffffff)
> >>>>>>>>>>>        iwlwifi 0000:01:00.0: 00000000: ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff
> >>>>>>>>>>>        iwlwifi 0000:01:00.0: Device gone - attempting removal
> >>>>>>>>>>>        Hardware became unavailable upon resume. This could be a software issue prior to suspend or a hardware issue.
> >>>>>>>>>>>
> >>>>>>>>>>> And then we re-enumerate 01:00.0 and it looks like it may have been
> >>>>>>>>>>> reset (BAR is 0):
> >>>>>>>>>>>
> >>>>>>>>>>>        pci 0000:01:00.0: [8086:095a] type 00 class 0x028000
> >>>>>>>>>>>        pci 0000:01:00.0: reg 0x10: [mem 0x00000000-0x00001fff 64bit]
> >>>>>>>>>>>
> >>>>>>>>>>> lspci diffs from before/after suspend:
> >>>>>>>>>>>
> >>>>>>>>>>>         00:14.0 PCI bridge: Intel Corporation Celeron N3350/Pentium N4200/Atom E3900 Series PCI Express Port B #1 (rev fb) (prog-if 00 [Normal decode])
> >>>>>>>>>>>           Bus: primary=00, secondary=01, subordinate=01, sec-latency=64
> >>>>>>>>>>>        -               DevSta: CorrErr- NonFatalErr+ FatalErr- UnsupReq+ AuxPwr+ TransPend-
> >>>>>>>>>>>        +               DevSta: CorrErr+ NonFatalErr- FatalErr- UnsupReq- AuxPwr+ TransPend-
> >>>>>>>>>>>        -               LnkCtl: ASPM L1 Enabled; RCB 64 bytes, Disabled- CommClk+
> >>>>>>>>>>>        +               LnkCtl: ASPM Disabled; RCB 64 bytes, Disabled- CommClk+
> >>>>>>>>>>>        -               LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
> >>>>>>>>>>>        +               LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete- EqualizationPhase1-
> >>>>>>>>>>>        -       Capabilities: [150 v0] Null
> >>>>>>>>>>>        -       Capabilities: [200 v1] L1 PM Substates
> >>>>>>>>>>>        -               L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
> >>>>>>>>>>>        -                         PortCommonModeRestoreTime=40us PortTPowerOnTime=10us
> >>>>>>>>>>>        -               L1SubCtl1: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+
> >>>>>>>>>>>        -                          T_CommonMode=40us LTR1.2_Threshold=98304ns
> >>>>>>>>>>>        -               L1SubCtl2: T_PwrOn=60us
> >>>>>>>>>>>
> >>>>>>>>>>> The DevSta differences might be BIOS bugs, probably not relevant.
> >>>>>>>>>>> Interesting that ASPM is disabled, maybe didn't get enabled after
> >>>>>>>>>>> re-enumerating 01:00.0?  Strange that the L1 PM Substates capability
> >>>>>>>>>>> disappeared.
> >>>>>>>>>>>
> >>>>>>>>>>>         01:00.0 Network controller: Intel Corporation Wireless 7265 (rev 59)
> >>>>>>>>>>>                        LnkCtl: ASPM L1 Enabled; RCB 64 bytes, Disabled- CommClk+
> >>>>>>>>>>>        -                       ExtSynch- ClockPM+ AutWidDis- BWInt- AutBWInt-
> >>>>>>>>>>>        +                       ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
> >>>>>>>>>>>                Capabilities: [154 v1] L1 PM Substates
> >>>>>>>>>>>                        L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
> >>>>>>>>>>>                                  PortCommonModeRestoreTime=30us PortTPowerOnTime=60us
> >>>>>>>>>>>        -               L1SubCtl1: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+
> >>>>>>>>>>>        -                          T_CommonMode=0us LTR1.2_Threshold=98304ns
> >>>>>>>>>>>        +               L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
> >>>>>>>>>>>        +                          T_CommonMode=0us LTR1.2_Threshold=0ns
> >>>>>>>>>>>
> >>>>>>>>>>> Dmesg claimed we reconfigured common clock config.  Maybe ASPM didn't
> >>>>>>>>>>> get reinitialized after re-enumeration?  Looks like we didn't restore
> >>>>>>>>>>> L1SubCtl1.
> >>>>>>>>>>>
> >>>>>>>>>>> Bjorn
> >>>>>>>>>>>
> >>>>>>>>
> >>>>>>>> Hi,
> >>>>>>>>
> >>>>>>>> Thank you all for the response and input! As Rajat mentioned I'm using
> >>>>>>>> chromebook - but not Atlas (Amberlake) - in this case it is Babymega
> >>>>>>>> (Apollolake)  - I will try to load most recent kernel and give it a
> >>>>>>>> try once again.
> >>>>>>>>
> >>>>>>>> Best regards,
> >>>>>>>> Lukasz
> >>>>>>>
> >>>>>>> Hi,
> >>>>>>>
> >>>>>>>      I have applied this patch on top of v5.19-rc7 (chromeos) and I'm
> >>>>>>> still getting same results:
> >>>>>>> https://gist.github.com/semihalf-majczak-lukasz/4b716704c21a3758d6711b2030ea34b9
> >>>>>>>
> >>>>>>> Best regards,
> >>>>>>> Lukasz
> >>>>>>>
> >>>>> Hi Vidya,
> >>>>>
> >>>>> Sorry for the long delay, I have retested your patch on top of
> >>>>> linux-next/master (next-20220802) - the results for my device remain
> >>>>> the same.
> >>>>> Here are the logs (lspci -vvv before suspend, lspci -vvv after resume and dmesg)
> >>>>> https://gist.github.com/semihalf-majczak-lukasz/c7bfd811359f23278034056a8002b3ef
> >>>>> Let me know if you need any more logs and/or tests.
> >>>>>
> >>>>> Best regards,
> >>>>> Lukasz
> >>>>>
> >>> Hi Vidya,
> >>>
> >>> After your last email, I've re-tested my setup and (without your
> >>> patch)  the capability register also disappears - so it looks there is
> >>> - in fact - some problem in my setup and your patch just brings it to
> >>> the top as after resume tries to write to a register that is no longer
> >>> present. I'm very sorry for the confusion here and I've not notice
> >>> that at the very beginning.
> >>>
> >>> Best regards,
> >>> Lukasz
> >>>

Hi Vidya,

For me (on Apollolake devices) the results remain the same, but as
I've mentioned earlier - it looks very much related exactly to the
Apollolake and is not directly related to your patch (e.g. I'm losing
L1SS capabilities even without your patch).
As a counter example, I don't  observe any issues with your patach
(v3) on Amberlake devices - lspci -vvv before suspend and after resume
are exactly the same.

Best regards,
Lukasz

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