Re: [PATCH V2] PCI/ASPM: Save/restore L1SS Capability for suspend/resume

From: Lukasz Majczak
Date: Tue Jul 26 2022 - 03:20:49 EST

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In reply to: Rajat Jain: "Re: [PATCH V2] PCI/ASPM: Save/restore L1SS Capability for suspend/resume"
Next in thread: Lukasz Majczak: "Re: [PATCH V2] PCI/ASPM: Save/restore L1SS Capability for suspend/resume"
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wt., 26 lip 2022 o 00:51 Rajat Jain <rajatja@xxxxxxxxxx> napisał(a):
>
> Hello,
>
> On Sat, Jul 23, 2022 at 10:03 AM Vidya Sagar <vidyas@xxxxxxxxxx> 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@xxxxxxxxxxxxx> napisał(a):
> > >>> On Fri, Jul 15, 2022 at 6:38 PM Ben Chuang <benchuanggli@xxxxxxxxx> wrote:
> > >>>> On Tue, Jul 5, 2022 at 2:00 PM Vidya Sagar <vidyas@xxxxxxxxxx> 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@xxxxxxxxxx>
> > >>>>> Tested-by: Abhishek Sahu <abhsahu@xxxxxxxxxx>
> > >>>>
> > >>>> 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@xxxxxxxxx>
> > >>>
> > >>> Forgot to add mine:
> > >>> Tested-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> > >>>
> > >>>>
> > >>>> Best regards,
> > >>>> Ben Chuang
> > >>>>
> > >>>>
> > >>>>> ---
> > >>>>> Hi,
> > >>>>> Kenneth R. Crudup <kenny@xxxxxxxxx>, 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@xxxxxxxxxxxxx/)
> > >> 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

Next message: Michael Guralnik: "[PATCH rdma-next v1 4/5] RDMA/mlx5: Store in the cache mkeys instead of mrs"
Previous message: Michael Guralnik: "[PATCH rdma-next v1 5/5] RDMA/mlx5: Rename the mkey cache variables and functions"
In reply to: Rajat Jain: "Re: [PATCH V2] PCI/ASPM: Save/restore L1SS Capability for suspend/resume"
Next in thread: Lukasz Majczak: "Re: [PATCH V2] PCI/ASPM: Save/restore L1SS Capability for suspend/resume"
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