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

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Date:   Tue, 26 Oct 2021 14:51:12 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     jesse.brandeburg@...el.com, anthony.l.nguyen@...el.com
Cc:     sasha.neftin@...el.com, acelan.kao@...onical.com,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Dima Ruinskiy <dima.ruinskiy@...el.com>,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [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 <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);
+		}
+
 		/* 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
-- 
2.32.0