Date: Mon, 14 May 2001 14:08:21 -0700 (PDT) From: Warner Losh <imp@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/pccard pcic.c Message-ID: <200105142108.f4EL8NS92464@freefall.freebsd.org>
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imp 2001/05/14 14:08:21 PDT
Modified files:
sys/pccard pcic.c
Log:
Fix the so called "static bug" in polling mode. Some desktop cards
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
Revision Changes Path
1.117 +34 -7 src/sys/pccard/pcic.c
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