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Fix the so called "static bug" in polling mode. Some desktop cards

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have bad grounding characteristics which allow small static discharges
(or sunspots, we're not 100% sure which) to reach the bridge chip.
This causes the bridge chip to wedge/reset itself.  There's no known
cure short of rebooting.

The bug manifests itself by the STAT_CHG return 0xff when read.  This
is impossible because the upper bits are reserved (and therefore
zero).  In addition, some of the lower bits are one only for memory
cards, which OLDCARD doesn't support, so if they are set, something
seriously foobar'd is going on.

So far we've seen this in exactly one brand of pcmcia <-> isa bridge
which plug and play identifies only as "VIA PCMCIA CARD".  This card
just has buffers on the isa card and the actual bridge chip on the
remote slot, which is connected by long ribbon cables.  We think this
long cable run, coupled with the lack of coupling capacitors is a
major reason why it is so static sensitive while its bretheren aren't.

Work Supported by: Timing Solutions, Inc.

MFC After: 3 days
This commit is contained in:
Warner Losh 2001-05-14 21:08:20 +00:00
parent 146e5df7bf
commit 07e0ca29b5
1 changed files with 33 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
sys/pccard/pcic.c
View File

@ -60,6 +60,7 @@
* Prototypes for interrupt handler.
*/
static driver_intr_t pcicintr;
static int pcicintr1(void *);
static int pcic_ioctl(struct slot *, int, caddr_t);
static int pcic_power(struct slot *);
static void pcic_mapirq(struct slot *, int);
@ -817,6 +818,15 @@ pcic_disable(struct slot *slt)
sp->putb(sp, PCIC_POWER, 0);
}
/*
* Wrapper function for pcicintr so that signatures match.
*/
static void
pcicintr(void *arg)
{
pcicintr1(arg);
}
/*
* PCIC timer. If the controller doesn't have a free IRQ to use
* or if interrupt steering doesn't work, poll the controller for
@ -825,7 +835,11 @@ pcic_disable(struct slot *slt)
static void
pcictimeout(void *chan)
{
pcicintr(chan);
if (pcicintr1(chan) != 0) {
printf("pcic%d: Static bug detected, ignoring hardware.\n",
(int) chan);
return;
}
pcictimeout_ch = timeout(pcictimeout, chan, hz/2);
}
@ -835,8 +849,8 @@ pcictimeout(void *chan)
* register. If this is non-zero, then a change has occurred
* on this card, so send an event to the main code.
*/
static void
pcicintr(void *arg)
static int
pcicintr1(void *arg)
{
int slot, s;
unsigned char chg;
@ -862,9 +876,21 @@ pcicintr(void *arg)
for (slot = 0; slot < PCIC_CARD_SLOTS; slot++, sp++) {
if (sp->slt &&
(chg = sp->getb(sp, PCIC_STAT_CHG)) != 0) {
if (bootverbose)
printf("Slot %d chg = 0x%x\n", slot,
chg);
/*
* if chg is 0xff, then we know that
* we've hit the famous "static bug" for
* some desktop pcmcia cards. This is
* caused by static discharge frying the
* poor card's mind and it starts return 0xff
* forever. We return an error and stop
* polling the card. When we're interrupt
* based, we never see this. The card just
* goes away silently.
*/
if (chg == 0xff) {
splx(s);
return (EIO);
}
if (chg & PCIC_CDTCH) {
if ((sp->getb(sp, PCIC_STATUS) &
PCIC_CD) == PCIC_CD) {
@ -880,6 +906,7 @@ pcicintr(void *arg)
}
}
splx(s);
return (0);
}
/*