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

On Tue, Oct 26, 2021 at 4:48 PM Sasha Neftin [off-list ref] wrote:

On 10/26/2021 09:51, Kai-Heng Feng wrote:

quoted

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 <redacted>
---
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

quoted

              /* 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