netdev - [PATCH net] e1000e: change usleep_range to udelay in PHY mdic access

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Date: Mon, 29 Apr 2024 10:10:40 -0700
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	netdev@...r.kernel.org
Cc: Vitaly Lifshits <vitaly.lifshits@...el.com>,
	anthony.l.nguyen@...el.com,
	regressions@...mhuis.info,
	stable@...r.kernel.org,
	Jérôme Carretero <cJ@...gloub.eu>,
	Sasha Neftin <sasha.neftin@...el.com>,
	Dima Ruinskiy <dima.ruinskiy@...el.com>
Subject: [PATCH net] e1000e: change usleep_range to udelay in PHY mdic access

From: Vitaly Lifshits <vitaly.lifshits@...el.com>

This is a partial revert of commit 6dbdd4de0362 ("e1000e: Workaround
for sporadic MDI error on Meteor Lake systems"). The referenced commit
used usleep_range inside the PHY access routines, which are sometimes
called from an atomic context. This can lead to a kernel panic in some
scenarios, such as cable disconnection and reconnection on vPro systems.

Solve this by changing the usleep_range calls back to udelay.

Fixes: 6dbdd4de0362 ("e1000e: Workaround for sporadic MDI error on Meteor Lake systems")
Cc: stable@...r.kernel.org
Reported-by: Jérôme Carretero <cJ@...gloub.eu>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218740
Closes: https://lore.kernel.org/lkml/a7eb665c74b5efb5140e6979759ed243072cb24a.camel@zougloub.eu/
Co-developed-by: Sasha Neftin <sasha.neftin@...el.com>
Signed-off-by: Sasha Neftin <sasha.neftin@...el.com>
Signed-off-by: Vitaly Lifshits <vitaly.lifshits@...el.com>
Tested-by: Dima Ruinskiy <dima.ruinskiy@...el.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/e1000e/phy.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/phy.c b/drivers/net/ethernet/intel/e1000e/phy.c
index 93544f1cc2a5..f7ae0e0aa4a4 100644
--- a/drivers/net/ethernet/intel/e1000e/phy.c
+++ b/drivers/net/ethernet/intel/e1000e/phy.c
@@ -157,7 +157,7 @@ s32 e1000e_read_phy_reg_mdic(struct e1000_hw *hw, u32 offset, u16 *data)
 		 * the lower time out
 		 */
 		for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
-			usleep_range(50, 60);
+			udelay(50);
 			mdic = er32(MDIC);
 			if (mdic & E1000_MDIC_READY)
 				break;
@@ -181,7 +181,7 @@ s32 e1000e_read_phy_reg_mdic(struct e1000_hw *hw, u32 offset, u16 *data)
 		 * reading duplicate data in the next MDIC transaction.
 		 */
 		if (hw->mac.type == e1000_pch2lan)
-			usleep_range(100, 150);
+			udelay(100);
 
 		if (success) {
 			*data = (u16)mdic;
@@ -237,7 +237,7 @@ s32 e1000e_write_phy_reg_mdic(struct e1000_hw *hw, u32 offset, u16 data)
 		 * the lower time out
 		 */
 		for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
-			usleep_range(50, 60);
+			udelay(50);
 			mdic = er32(MDIC);
 			if (mdic & E1000_MDIC_READY)
 				break;
@@ -261,7 +261,7 @@ s32 e1000e_write_phy_reg_mdic(struct e1000_hw *hw, u32 offset, u16 data)
 		 * reading duplicate data in the next MDIC transaction.
 		 */
 		if (hw->mac.type == e1000_pch2lan)
-			usleep_range(100, 150);
+			udelay(100);
 
 		if (success)
 			return 0;
-- 
2.41.0