Re: [PATCH v2] e1000e: Add a delay to let ME unconfigure s0ix when DPG_EXIT_DONE is already flagged

[Sasha Neftin]

On 10/27/2021 01:50, Kai-Heng Feng wrote:
> On Tue, Oct 26, 2021 at 4:48 PM Sasha Neftin <sasha.neftin@xxxxxxxxx> 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@xxxxxxxxxxxxx>
> > > ---
> > > 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)
> > >                /* 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