linux-kernel - [PATCH] ixgbe: check Master Disable bit after setting

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Date:	Mon, 26 Oct 2015 20:19:52 -0400
From:	dan.streetman@...onical.com
To:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	Shannon Nelson <shannon.nelson@...el.com>,
	Carolyn Wyborny <carolyn.wyborny@...el.com>,
	Don Skidmore <donald.c.skidmore@...el.com>,
	Matthew Vick <matthew.vick@...el.com>,
	John Ronciak <john.ronciak@...el.com>,
	Mitch Williams <mitch.a.williams@...el.com>,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Dan Streetman <dan.streetman@...onical.com>,
	Dan Streetman <ddstreet@...e.org>
Subject: [PATCH] ixgbe: check Master Disable bit after setting

From: Dan Streetman <dan.streetman@...onical.com>

Spec section 8.2.4.1.1 notes that after setting the PCIe Master Disable
bit, it must be read to verify it was set before polling the Master Enable
status bit.

This adds the check to verify the Master Disable bit was set.

This also corrects the spec section number reference - the Master Disable
section is 5.2.4.3.2, not 5.2.5.3.2.

Signed-off-by: Dan Streetman <dan.streetman@...onical.com>
Signed-off-by: Dan Streetman <ddstreet@...e.org>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_common.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_common.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_common.c
index 3f56a80..abfada7 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_common.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_common.c
@@ -2453,6 +2453,16 @@ static s32 ixgbe_disable_pcie_master(struct ixgbe_hw *hw)
 	/* Always set this bit to ensure any future transactions are blocked */
 	IXGBE_WRITE_REG(hw, IXGBE_CTRL, IXGBE_CTRL_GIO_DIS);
 
+	/* Spec sec 8.2.4.1.1, Master Disable bit :
+	 * "After doing any change to this bit the host must read that
+	 *  the bit has been modified as expected before reading
+	 *  STATUS.PCIe Master Enable Status bit."
+	 */
+	if (!(IXGBE_READ_REG(hw, IXGBE_CTRL) & IXGBE_CTRL_GIO_DIS)) {
+		hw_err(hw, "GIO Master Disable bit didn't set\n");
+		goto gio_dis_fail;
+	}
+
 	/* Exit if master requests are blocked */
 	if (!(IXGBE_READ_REG(hw, IXGBE_STATUS) & IXGBE_STATUS_GIO) ||
 	    ixgbe_removed(hw->hw_addr))
@@ -2467,13 +2477,14 @@ static s32 ixgbe_disable_pcie_master(struct ixgbe_hw *hw)
 
 	/*
 	 * Two consecutive resets are required via CTRL.RST per datasheet
-	 * 5.2.5.3.2 Master Disable.  We set a flag to inform the reset routine
+	 * 5.2.4.3.2 Master Disable.  We set a flag to inform the reset routine
 	 * of this need.  The first reset prevents new master requests from
 	 * being issued by our device.  We then must wait 1usec or more for any
 	 * remaining completions from the PCIe bus to trickle in, and then reset
 	 * again to clear out any effects they may have had on our device.
 	 */
 	hw_dbg(hw, "GIO Master Disable bit didn't clear - requesting resets\n");
+gio_dis_fail:
 	hw->mac.flags |= IXGBE_FLAGS_DOUBLE_RESET_REQUIRED;
 
 	/*
-- 
2.5.0

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