acpiec madness (HP laptop people pay attention to this one) - tested on some HP Compaq platforms

[Denis Lapshin]

Two years ago Marco issued a patch in order to prevent incorrect
reading acpitz on HP Compaq (or any HP laptops with acpiec madness) by
adding some delays to have data prepared to read/write.

It has been tested and works perfectly fine on some HP laptops: 6510b,
8510p/w, 8710p/w.

Please add this patch into the source tree to have it by default.

Index: acpiec.c
===================================================================
RCS file: /cvs/src/sys/dev/acpi/acpiec.c,v
retrieving revision 1.43
diff -u -p -r1.43 acpiec.c
--- acpiec.c    8 Aug 2010 17:25:41 -0000       1.43
+++ acpiec.c    29 Sep 2010 04:24:13 -0000
@@ -92,7 +92,7 @@ void
 acpiec_wait(struct acpiec_softc *sc, u_int8_t mask, u_int8_t val)
 {
        static int acpiecnowait;
-       u_int8_t                stat;
+       volatile u_int8_t stat;

        dnprintf(40, "%s: EC wait_ns for: %b == %02x\n",
            DEVNAME(sc), (int)mask,
@@ -104,8 +104,14 @@ acpiec_wait(struct acpiec_softc *sc, u_i
                if (cold || (stat & EC_STAT_BURST))
                        delay(1);
                else
-                       tsleep(&acpiecnowait, PWAIT, "acpiec", 1);
+                       tsleep(&acpiecnowait, PWAIT, "ecstat", 1);
        }
+
+       /* delay to make sure the data is actually ready */
+       if (cold)
+               delay(10);
+       else
+               tsleep(&acpiecnowait, PWAIT, "ecout", 1);

        dnprintf(40, "%s: EC wait_ns, stat: %b\n", DEVNAME(sc), (int)stat,
            "\20\x8IGN\x7SMI\x6SCI\05BURST\04CMD\03IGN\02IBF\01OBF");