e1000e: Workaround for sporadic MDI error on Meteor Lake systems

On some Meteor Lake systems accessing the PHY via the MDIO interface may
result in an MDI error. This issue happens sporadically and in most cases
a second access to the PHY via the MDIO interface results in success.

As a workaround, introduce a retry counter which is set to 3 on Meteor
Lake systems. The driver will only return an error if 3 consecutive PHY
access attempts fail. The retry mechanism is disabled in specific flows,
where MDI errors are expected.

Fixes: cc23f4f0b6b9 ("e1000e: Add support for Meteor Lake")
Suggested-by: Nikolay Mushayev <nikolay.mushayev@intel.com>
Co-developed-by: Nir Efrati <nir.efrati@intel.com>
Signed-off-by: Nir Efrati <nir.efrati@intel.com>
Signed-off-by: Vitaly Lifshits <vitaly.lifshits@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 113 insertions, 69 deletions

diff --git a/drivers/net/ethernet/intel/e1000e/phy.c b/drivers/net/ethernet/intel/e1000e/phy.c
index 5e329156d1ba..93544f1cc2a5 100644
--- a/drivers/net/ethernet/intel/e1000e/phy.c
+++ b/drivers/net/ethernet/intel/e1000e/phy.c
@@ -107,6 +107,16 @@ s32 e1000e_phy_reset_dsp(struct e1000_hw *hw)
 	return e1e_wphy(hw, M88E1000_PHY_GEN_CONTROL, 0);
 }
 
+void e1000e_disable_phy_retry(struct e1000_hw *hw)
+{
+	hw->phy.retry_enabled = false;
+}
+
+void e1000e_enable_phy_retry(struct e1000_hw *hw)
+{
+	hw->phy.retry_enabled = true;
+}
+
 /**
  *  e1000e_read_phy_reg_mdic - Read MDI control register
  *  @hw: pointer to the HW structure
@@ -118,55 +128,73 @@ s32 e1000e_phy_reset_dsp(struct e1000_hw *hw)
  **/
 s32 e1000e_read_phy_reg_mdic(struct e1000_hw *hw, u32 offset, u16 *data)
 {
+	u32 i, mdic = 0, retry_counter, retry_max;
 	struct e1000_phy_info *phy = &hw->phy;
-	u32 i, mdic = 0;
+	bool success;
 
 	if (offset > MAX_PHY_REG_ADDRESS) {
 		e_dbg("PHY Address %d is out of range\n", offset);
 		return -E1000_ERR_PARAM;
 	}
 
+	retry_max = phy->retry_enabled ? phy->retry_count : 0;
+
 	/* Set up Op-code, Phy Address, and register offset in the MDI
 	 * Control register.  The MAC will take care of interfacing with the
 	 * PHY to retrieve the desired data.
 	 */
-	mdic = ((offset << E1000_MDIC_REG_SHIFT) |
-		(phy->addr << E1000_MDIC_PHY_SHIFT) |
-		(E1000_MDIC_OP_READ));
+	for (retry_counter = 0; retry_counter <= retry_max; retry_counter++) {
+		success = true;
 
-	ew32(MDIC, mdic);
+		mdic = ((offset << E1000_MDIC_REG_SHIFT) |
+			(phy->addr << E1000_MDIC_PHY_SHIFT) |
+			(E1000_MDIC_OP_READ));
 
-	/* Poll the ready bit to see if the MDI read completed
-	 * Increasing the time out as testing showed failures with
-	 * the lower time out
-	 */
-	for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
-		udelay(50);
-		mdic = er32(MDIC);
-		if (mdic & E1000_MDIC_READY)
-			break;
-	}
-	if (!(mdic & E1000_MDIC_READY)) {
-		e_dbg("MDI Read PHY Reg Address %d did not complete\n", offset);
-		return -E1000_ERR_PHY;
-	}
-	if (mdic & E1000_MDIC_ERROR) {
-		e_dbg("MDI Read PHY Reg Address %d Error\n", offset);
-		return -E1000_ERR_PHY;
-	}
-	if (FIELD_GET(E1000_MDIC_REG_MASK, mdic) != offset) {
-		e_dbg("MDI Read offset error - requested %d, returned %d\n",
-		      offset, FIELD_GET(E1000_MDIC_REG_MASK, mdic));
-		return -E1000_ERR_PHY;
+		ew32(MDIC, mdic);
+
+		/* Poll the ready bit to see if the MDI read completed
+		 * Increasing the time out as testing showed failures with
+		 * the lower time out
+		 */
+		for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
+			usleep_range(50, 60);
+			mdic = er32(MDIC);
+			if (mdic & E1000_MDIC_READY)
+				break;
+		}
+		if (!(mdic & E1000_MDIC_READY)) {
+			e_dbg("MDI Read PHY Reg Address %d did not complete\n",
+			      offset);
+			success = false;
+		}
+		if (mdic & E1000_MDIC_ERROR) {
+			e_dbg("MDI Read PHY Reg Address %d Error\n", offset);
+			success = false;
+		}
+		if (FIELD_GET(E1000_MDIC_REG_MASK, mdic) != offset) {
+			e_dbg("MDI Read offset error - requested %d, returned %d\n",
+			      offset, FIELD_GET(E1000_MDIC_REG_MASK, mdic));
+			success = false;
+		}
+
+		/* Allow some time after each MDIC transaction to avoid
+		 * reading duplicate data in the next MDIC transaction.
+		 */
+		if (hw->mac.type == e1000_pch2lan)
+			usleep_range(100, 150);
+
+		if (success) {
+			*data = (u16)mdic;
+			return 0;
+		}
+
+		if (retry_counter != retry_max) {
+			e_dbg("Perform retry on PHY transaction...\n");
+			mdelay(10);
+		}
 	}
-	*data = (u16)mdic;
 
-	/* Allow some time after each MDIC transaction to avoid
-	 * reading duplicate data in the next MDIC transaction.
-	 */
-	if (hw->mac.type == e1000_pch2lan)
-		udelay(100);
-	return 0;
+	return -E1000_ERR_PHY;
 }
 
 /**
@@ -179,56 +207,72 @@ s32 e1000e_read_phy_reg_mdic(struct e1000_hw *hw, u32 offset, u16 *data)
  **/
 s32 e1000e_write_phy_reg_mdic(struct e1000_hw *hw, u32 offset, u16 data)
 {
+	u32 i, mdic = 0, retry_counter, retry_max;
 	struct e1000_phy_info *phy = &hw->phy;
-	u32 i, mdic = 0;
+	bool success;
 
 	if (offset > MAX_PHY_REG_ADDRESS) {
 		e_dbg("PHY Address %d is out of range\n", offset);
 		return -E1000_ERR_PARAM;
 	}
 
+	retry_max = phy->retry_enabled ? phy->retry_count : 0;
+
 	/* Set up Op-code, Phy Address, and register offset in the MDI
 	 * Control register.  The MAC will take care of interfacing with the
 	 * PHY to retrieve the desired data.
 	 */
-	mdic = (((u32)data) |
-		(offset << E1000_MDIC_REG_SHIFT) |
-		(phy->addr << E1000_MDIC_PHY_SHIFT) |
-		(E1000_MDIC_OP_WRITE));
+	for (retry_counter = 0; retry_counter <= retry_max; retry_counter++) {
+		success = true;
 
-	ew32(MDIC, mdic);
+		mdic = (((u32)data) |
+			(offset << E1000_MDIC_REG_SHIFT) |
+			(phy->addr << E1000_MDIC_PHY_SHIFT) |
+			(E1000_MDIC_OP_WRITE));
 
-	/* Poll the ready bit to see if the MDI read completed
-	 * Increasing the time out as testing showed failures with
-	 * the lower time out
-	 */
-	for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
-		udelay(50);
-		mdic = er32(MDIC);
-		if (mdic & E1000_MDIC_READY)
-			break;
-	}
-	if (!(mdic & E1000_MDIC_READY)) {
-		e_dbg("MDI Write PHY Reg Address %d did not complete\n", offset);
-		return -E1000_ERR_PHY;
-	}
-	if (mdic & E1000_MDIC_ERROR) {
-		e_dbg("MDI Write PHY Red Address %d Error\n", offset);
-		return -E1000_ERR_PHY;
-	}
-	if (FIELD_GET(E1000_MDIC_REG_MASK, mdic) != offset) {
-		e_dbg("MDI Write offset error - requested %d, returned %d\n",
-		      offset, FIELD_GET(E1000_MDIC_REG_MASK, mdic));
-		return -E1000_ERR_PHY;
-	}
+		ew32(MDIC, mdic);
 
-	/* Allow some time after each MDIC transaction to avoid
-	 * reading duplicate data in the next MDIC transaction.
-	 */
-	if (hw->mac.type == e1000_pch2lan)
-		udelay(100);
+		/* Poll the ready bit to see if the MDI read completed
+		 * Increasing the time out as testing showed failures with
+		 * the lower time out
+		 */
+		for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
+			usleep_range(50, 60);
+			mdic = er32(MDIC);
+			if (mdic & E1000_MDIC_READY)
+				break;
+		}
+		if (!(mdic & E1000_MDIC_READY)) {
+			e_dbg("MDI Write PHY Reg Address %d did not complete\n",
+			      offset);
+			success = false;
+		}
+		if (mdic & E1000_MDIC_ERROR) {
+			e_dbg("MDI Write PHY Reg Address %d Error\n", offset);
+			success = false;
+		}
+		if (FIELD_GET(E1000_MDIC_REG_MASK, mdic) != offset) {
+			e_dbg("MDI Write offset error - requested %d, returned %d\n",
+			      offset, FIELD_GET(E1000_MDIC_REG_MASK, mdic));
+			success = false;
+		}
 
-	return 0;
+		/* Allow some time after each MDIC transaction to avoid
+		 * reading duplicate data in the next MDIC transaction.
+		 */
+		if (hw->mac.type == e1000_pch2lan)
+			usleep_range(100, 150);
+
+		if (success)
+			return 0;
+
+		if (retry_counter != retry_max) {
+			e_dbg("Perform retry on PHY transaction...\n");
+			mdelay(10);
+		}
+	}
+
+	return -E1000_ERR_PHY;
 }
 
 /**