From: Scott Moser <smoser@redhat.com>
Subject: [PATCH RHEL5.1] bz232004 [ppc] Disable PCI-e completion timeouts on 	I/O Adapters
Date: Tue, 31 Jul 2007 12:40:24 -0400 (EDT)
Bugzilla: 232004
Message-Id: <Pine.LNX.4.64.0707311238590.30310@squad5-lp1.lab.boston.redhat.com>
Changelog: [ppc] Disable PCI-e completion timeouts on I/O Adapters


RHBZ#: 232004
------
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=232004

Description:
------------
This fix is needed for supporting Intel-based 10/100Mb/1Gb Ethernet
PCI-Express adapters on p6 systems.  This fixes an issue regarding the
PCIe IO completion timing on power systems. The direct impact of the issue
is DMA error and data corruption. The problem exists today and will
surface much more seriously when the adapter is to be operating in the
PCIe IO drawers by end of 2007.

This patch is a workaround of this problem. It is proven by both Intel and
IBM  that by disabling the completion timeout the problem is avoided and
there is no data corruption any more.

RHEL Version Found:
-------------------
This is a bug found in RHEL5u1 kernel 2.6.18-36.el5

Upstream Status:
----------------
This patch has been submitted to netdev mailing list at [1]. It represents
a workaround for the issue.  A more comprehensive patch will likely be
applied upstream [2], but this will workaround will be fine for RHEL.

Test Status:
------------
To ensure cross-platform build, this code has been built with brew
--scratch against a 2.6.18-36.el5 kernel and is available at [3].

Both Intel and IBM have verirfied that this patch fixes the problem.

Proposed Patch:
----------------
Please review and ACK for RHEL5.1

--
[1] http://lists.openwall.net/netdev/2007/05/16/51
[2] http://article.gmane.org/gmane.linux.network/67432

Index: b/drivers/net/e1000/e1000_hw.c
===================================================================
--- a/drivers/net/e1000/e1000_hw.c
+++ b/drivers/net/e1000/e1000_hw.c
@@ -1018,6 +1018,13 @@ e1000_init_hw(struct e1000_hw *hw)
         break;
     }
 
+#if defined(CONFIG_PPC64) || defined(CONFIG_PPC)
+    if (hw->mac_type == e1000_82571) {
+        uint32_t gcr = E1000_READ_REG(hw, GCR);
+        gcr |= E1000_GCR_DISABLE_TIMEOUT_MECHANISM;
+        E1000_WRITE_REG(hw, GCR, gcr);
+    }
+#endif
 
     if (hw->mac_type == e1000_82573) {
         uint32_t gcr = E1000_READ_REG(hw, GCR);
Index: b/drivers/net/e1000/e1000_hw.h
===================================================================
--- a/drivers/net/e1000/e1000_hw.h
+++ b/drivers/net/e1000/e1000_hw.h
@@ -2207,6 +2207,7 @@ struct e1000_host_command_info {
 #define PCI_EX_82566_SNOOP_ALL PCI_EX_NO_SNOOP_ALL
 
 #define E1000_GCR_L1_ACT_WITHOUT_L0S_RX 0x08000000
+#define E1000_GCR_DISABLE_TIMEOUT_MECHANISM 0x80000000
 /* Function Active and Power State to MNG */
 #define E1000_FACTPS_FUNC0_POWER_STATE_MASK         0x00000003
 #define E1000_FACTPS_LAN0_VALID                     0x00000004