linux-kernel - Re: [PATCH v2] e1000e: Add a delay to let ME unconfigure s0ix when DPG_EXIT

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Date:   Tue, 2 Nov 2021 11:27:59 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Sasha Neftin <sasha.neftin@...el.com>
Cc:     Jesse Brandeburg <jesse.brandeburg@...el.com>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        AceLan Kao <acelan.kao@...onical.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Dima Ruinskiy <dima.ruinskiy@...el.com>,
        "moderated list:INTEL ETHERNET DRIVERS" 
        <intel-wired-lan@...ts.osuosl.org>,
        Linux Netdev List <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "Kraus, NechamaX" <nechamax.kraus@...ux.intel.com>,
        "Fuxbrumer, Devora" <devora.fuxbrumer@...el.com>,
        "Avivi, Amir" <amir.avivi@...el.com>
Subject: Re: [PATCH v2] e1000e: Add a delay to let ME unconfigure s0ix when
 DPG_EXIT_DONE is already flagged

On Fri, Oct 29, 2021 at 5:14 PM Sasha Neftin <sasha.neftin@...el.com> wrote:
>
> On 10/27/2021 01:50, Kai-Heng Feng wrote:
> > On Tue, Oct 26, 2021 at 4:48 PM Sasha Neftin <sasha.neftin@...el.com> wrote:
> >>
> >> On 10/26/2021 09:51, Kai-Heng Feng wrote:
> >>> On some ADL platforms, DPG_EXIT_DONE is always flagged so e1000e resume
> >>> polling logic doesn't wait until ME really unconfigures s0ix.
> >>>
> >>> So check DPG_EXIT_DONE before issuing EXIT_DPG, and if it's already
> >>> flagged, wait for 1 second to let ME unconfigure s0ix.
> >>>
> >>> Fixes: 3e55d231716e ("e1000e: Add handshake with the CSME to support S0ix")
> >>> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=214821
> >>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> >>> ---
> >>> v2:
> >>>    Add missing "Fixes:" tag
> >>>
> >>>    drivers/net/ethernet/intel/e1000e/netdev.c | 7 +++++++
> >>>    1 file changed, 7 insertions(+)
> >>>
> >>> diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
> >>> index 44e2dc8328a22..cd81ba00a6bc9 100644
> >>> --- a/drivers/net/ethernet/intel/e1000e/netdev.c
> >>> +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
> >>> @@ -6493,14 +6493,21 @@ static void e1000e_s0ix_exit_flow(struct e1000_adapter *adapter)
> >>>        u32 mac_data;
> >>>        u16 phy_data;
> >>>        u32 i = 0;
> >>> +     bool dpg_exit_done;
> >>>
> >>>        if (er32(FWSM) & E1000_ICH_FWSM_FW_VALID) {
> >>> +             dpg_exit_done = er32(EXFWSM) & E1000_EXFWSM_DPG_EXIT_DONE;
> >>>                /* Request ME unconfigure the device from S0ix */
> >>>                mac_data = er32(H2ME);
> >>>                mac_data &= ~E1000_H2ME_START_DPG;
> >>>                mac_data |= E1000_H2ME_EXIT_DPG;
> >>>                ew32(H2ME, mac_data);
> >>>
> >>> +             if (dpg_exit_done) {
> >>> +                     e_warn("DPG_EXIT_DONE is already flagged. This is a firmware bug\n");
> >>> +                     msleep(1000);
> >>> +             }
> >> Thanks for working on the enablement.
> >> The delay approach is fragile. We need to work with CSME folks to
> >> understand why _DPG_EXIT_DONE indication is wrong on some ADL platforms.
> >> Could you provide CSME/BIOS version? dmidecode -t 0 and cat
> >> /sys/class/mei/mei0/fw_ver
> >
> > $ sudo dmidecode -t 0
> > # dmidecode 3.2
> > Getting SMBIOS data from sysfs.
> > SMBIOS 3.4 present.
> > # SMBIOS implementations newer than version 3.2.0 are not
> > # fully supported by this version of dmidecode.
> >
> > Handle 0x0001, DMI type 0, 26 bytes
> > BIOS Information
> >          Vendor: Dell Inc.
> >          Version: 0.12.68
> >          Release Date: 10/01/2021
> >          ROM Size: 48 MB
> >          Characteristics:
> >                  PCI is supported
> >                  PNP is supported
> >                  BIOS is upgradeable
> >                  BIOS shadowing is allowed
> >                  Boot from CD is supported
> >                  Selectable boot is supported
> >                  EDD is supported
> >                  Print screen service is supported (int 5h)
> >                  8042 keyboard services are supported (int 9h)
> >                  Serial services are supported (int 14h)
> >                  Printer services are supported (int 17h)
> >                  ACPI is supported
> >                  USB legacy is supported
> >                  BIOS boot specification is supported
> >                  Function key-initiated network boot is supported
> >                  Targeted content distribution is supported
> >                  UEFI is supported
> >          BIOS Revision: 0.12
> >
> > $ cat /sys/class/mei/mei0/fw_ver
> > 0:16.0.15.1518
> > 0:16.0.15.1518
> > 0:16.0.15.1518
> >
> Thank you Kai-Heng. The _DPG_EXIT_DONE bit indication comes from the
> EXFWSM register controlled by the CSME. We have only read access.  I
> realized that this indication was set to 1 even before our request to
> unconfigure the s0ix settings from the CSME. I am wondering. Does after
> a ~ 1s delay (or less, or more) _DPG_EXIT_DONE indication eventually
> change by CSME to 0? (is it consistently)

Never. It's consistently being 1.

Right now we are seeing the same issue on TGL, so I wonder if it's
better to just revert the CSME series?

Kai-Heng

> >>>                /* Poll up to 2.5 seconds for ME to unconfigure DPG.
> >>>                 * If this takes more than 1 second, show a warning indicating a
> >>>                 * firmware bug
> >>>
>