netdev - [net-next 08/12] e1000e: Tx hang on I218 when linked at 100Half and slow response at 10Mbps

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Date:	Sun, 28 Jul 2013 04:41:12 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	davem@...emloft.net
Cc:	Bruce Allan <bruce.w.allan@...el.com>, netdev@...r.kernel.org,
	gospo@...hat.com, sassmann@...hat.com,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next 08/12] e1000e: Tx hang on I218 when linked at 100Half and slow response at 10Mbps

From: Bruce Allan <bruce.w.allan@...el.com>

Tx hang is an unintended consequence of another workaround that is in the
EEPROM for an issue with the firmware at 10Mbps when K1 (a power mode of
the MAC-PHY interconnect) is enabled.  The issue is resolved by setting
appropriate Tx re-transmission timeouts in the PHY and associated K1 entry
times in the MAC to allow enough transmissions to occur without triggering
a Tx hang.  A similar change is needed when linked at 10Mbps to improve
latency.

Signed-off-by: Bruce Allan <bruce.w.allan@...el.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
 drivers/net/ethernet/intel/e1000e/ich8lan.c | 49 ++++++++++++++++++++++++-----
 drivers/net/ethernet/intel/e1000e/ich8lan.h |  6 ++++
 2 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c
index 9dde390..b56c61a 100644
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -793,29 +793,31 @@ release:
  *  When K1 is enabled for 1Gbps, the MAC can miss 2 DMA completion indications
  *  preventing further DMA write requests.  Workaround the issue by disabling
  *  the de-assertion of the clock request when in 1Gpbs mode.
+ *  Also, set appropriate Tx re-transmission timeouts for 10 and 100Half link
+ *  speeds in order to avoid Tx hangs.
  **/
 static s32 e1000_k1_workaround_lpt_lp(struct e1000_hw *hw, bool link)
 {
 	u32 fextnvm6 = er32(FEXTNVM6);
+	u32 status = er32(STATUS);
 	s32 ret_val = 0;
+	u16 reg;
 
-	if (link && (er32(STATUS) & E1000_STATUS_SPEED_1000)) {
-		u16 kmrn_reg;
-
+	if (link && (status & E1000_STATUS_SPEED_1000)) {
 		ret_val = hw->phy.ops.acquire(hw);
 		if (ret_val)
 			return ret_val;
 
 		ret_val =
 		    e1000e_read_kmrn_reg_locked(hw, E1000_KMRNCTRLSTA_K1_CONFIG,
-						&kmrn_reg);
+						&reg);
 		if (ret_val)
 			goto release;
 
 		ret_val =
 		    e1000e_write_kmrn_reg_locked(hw,
 						 E1000_KMRNCTRLSTA_K1_CONFIG,
-						 kmrn_reg &
+						 reg &
 						 ~E1000_KMRNCTRLSTA_K1_ENABLE);
 		if (ret_val)
 			goto release;
@@ -827,12 +829,45 @@ static s32 e1000_k1_workaround_lpt_lp(struct e1000_hw *hw, bool link)
 		ret_val =
 		    e1000e_write_kmrn_reg_locked(hw,
 						 E1000_KMRNCTRLSTA_K1_CONFIG,
-						 kmrn_reg);
+						 reg);
 release:
 		hw->phy.ops.release(hw);
 	} else {
 		/* clear FEXTNVM6 bit 8 on link down or 10/100 */
-		ew32(FEXTNVM6, fextnvm6 & ~E1000_FEXTNVM6_REQ_PLL_CLK);
+		fextnvm6 &= ~E1000_FEXTNVM6_REQ_PLL_CLK;
+
+		if (!link || ((status & E1000_STATUS_SPEED_100) &&
+			      (status & E1000_STATUS_FD)))
+			goto update_fextnvm6;
+
+		ret_val = e1e_rphy(hw, I217_INBAND_CTRL, &reg);
+		if (ret_val)
+			return ret_val;
+
+		/* Clear link status transmit timeout */
+		reg &= ~I217_INBAND_CTRL_LINK_STAT_TX_TIMEOUT_MASK;
+
+		if (status & E1000_STATUS_SPEED_100) {
+			/* Set inband Tx timeout to 5x10us for 100Half */
+			reg |= 5 << I217_INBAND_CTRL_LINK_STAT_TX_TIMEOUT_SHIFT;
+
+			/* Do not extend the K1 entry latency for 100Half */
+			fextnvm6 &= ~E1000_FEXTNVM6_ENABLE_K1_ENTRY_CONDITION;
+		} else {
+			/* Set inband Tx timeout to 50x10us for 10Full/Half */
+			reg |= 50 <<
+			    I217_INBAND_CTRL_LINK_STAT_TX_TIMEOUT_SHIFT;
+
+			/* Extend the K1 entry latency for 10 Mbps */
+			fextnvm6 |= E1000_FEXTNVM6_ENABLE_K1_ENTRY_CONDITION;
+		}
+
+		ret_val = e1e_wphy(hw, I217_INBAND_CTRL, reg);
+		if (ret_val)
+			return ret_val;
+
+update_fextnvm6:
+		ew32(FEXTNVM6, fextnvm6);
 	}
 
 	return ret_val;
diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.h b/drivers/net/ethernet/intel/e1000e/ich8lan.h
index 80034a2..5986569 100644
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.h
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.h
@@ -93,6 +93,7 @@
 #define E1000_FEXTNVM4_BEACON_DURATION_16USEC	0x3
 
 #define E1000_FEXTNVM6_REQ_PLL_CLK	0x00000100
+#define E1000_FEXTNVM6_ENABLE_K1_ENTRY_CONDITION	0x00000200
 
 #define PCIE_ICH8_SNOOP_ALL	PCIE_NO_SNOOP_ALL
 
@@ -197,6 +198,11 @@
 
 #define SW_FLAG_TIMEOUT		1000	/* SW Semaphore flag timeout in ms */
 
+/* Inband Control */
+#define I217_INBAND_CTRL				PHY_REG(770, 18)
+#define I217_INBAND_CTRL_LINK_STAT_TX_TIMEOUT_MASK	0x3F00
+#define I217_INBAND_CTRL_LINK_STAT_TX_TIMEOUT_SHIFT	8
+
 /* PHY Low Power Idle Control */
 #define I82579_LPI_CTRL				PHY_REG(772, 20)
 #define I82579_LPI_CTRL_100_ENABLE		0x2000
-- 
1.7.11.7

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