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

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);
+		}