[src/trunk]: src/sys/dev/pci Fix a PCH2 specific bug that wrong register valu...

[msaitoh <msaitoh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/23987ec44c1c
branches:  trunk
changeset: 836724:23987ec44c1c
user:      msaitoh <msaitoh%NetBSD.org@localhost>
date:      Fri Nov 02 08:04:42 2018 +0000

description:
Fix a PCH2 specific bug that wrong register value can be read when boot.
When a wrong value is read when boot, the read device ID was incorrect and
ukphy(3) is attached instead of ihphy(4). The bug might also result in
MDIC read/write error.

 How to reproduce:

  0) Boot Windows.
  1) Leave some minutes.
  2) Reboot to NetBSD.

 To fix this problem, adding extra 100us delay at the end of
wm_gmii_mdic_{read,write}reg() on PCH2. Same as FreeBSD and linux.

 Reported by David Brownlee a few days ago and also reported by jmcneill
a half year ago. Tested with my own Thinkpad X220.

XXX pullup-[78]

diffstat:

 sys/dev/pci/if_wm.c |  29 +++++++++++++++++++++++------
 1 files changed, 23 insertions(+), 6 deletions(-)

diffs (72 lines):

diff -r adc0a3a92192 -r 23987ec44c1c sys/dev/pci/if_wm.c
--- a/sys/dev/pci/if_wm.c       Fri Nov 02 04:17:39 2018 +0000
+++ b/sys/dev/pci/if_wm.c       Fri Nov 02 08:04:42 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_wm.c,v 1.591 2018/11/02 03:22:19 msaitoh Exp $      */
+/*     $NetBSD: if_wm.c,v 1.592 2018/11/02 08:04:42 msaitoh Exp $      */
 
 /*
  * Copyright (c) 2001, 2002, 2003, 2004 Wasabi Systems, Inc.
@@ -83,7 +83,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_wm.c,v 1.591 2018/11/02 03:22:19 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_wm.c,v 1.592 2018/11/02 08:04:42 msaitoh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_net_mpsafe.h"
@@ -10096,19 +10096,26 @@
        if ((mdic & MDIC_READY) == 0) {
                log(LOG_WARNING, "%s: MDIC read timed out: phy %d reg %d\n",
                    device_xname(dev), phy, reg);
-               rv = 0;
+               return 0;
        } else if (mdic & MDIC_E) {
 #if 0 /* This is normal if no PHY is present. */
                log(LOG_WARNING, "%s: MDIC read error: phy %d reg %d\n",
                    device_xname(dev), phy, reg);
 #endif
-               rv = 0;
+               return 0;
        } else {
                rv = MDIC_DATA(mdic);
                if (rv == 0xffff)
                        rv = 0;
        }
 
+       /*
+        * Allow some time after each MDIC transaction to avoid
+        * reading duplicate data in the next MDIC transaction.
+        */
+       if (sc->sc_type == WM_T_PCH2)
+               delay(100);
+
        return rv;
 }
 
@@ -10140,12 +10147,22 @@
                delay(50);
        }
 
-       if ((mdic & MDIC_READY) == 0)
+       if ((mdic & MDIC_READY) == 0) {
                log(LOG_WARNING, "%s: MDIC write timed out: phy %d reg %d\n",
                    device_xname(dev), phy, reg);
-       else if (mdic & MDIC_E)
+               return;
+       } else if (mdic & MDIC_E) {
                log(LOG_WARNING, "%s: MDIC write error: phy %d reg %d\n",
                    device_xname(dev), phy, reg);
+               return;
+       }
+
+       /*
+        * Allow some time after each MDIC transaction to avoid
+        * reading duplicate data in the next MDIC transaction.
+        */
+       if (sc->sc_type == WM_T_PCH2)
+               delay(100);
 }
 
 /*