From 9d2446138e1775917e00191055e258277dab9083 Mon Sep 17 00:00:00 2001 From: Theo de Raadt Date: Tue, 20 Oct 1998 23:31:07 +0000 Subject: when transmitting we cannot totally fill the circular buffer (i.e. we can't use up all of the remaining sc->txslot[chan].bfree free bytes) because that would cause the circular buffer read pointer to become equal to the write pointer, thus signaling 'empty buffer' to the hardware and stopping the transmitter. spotted and fixed by Kenjiro Cho --- sys/dev/ic/midway.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'sys') diff --git a/sys/dev/ic/midway.c b/sys/dev/ic/midway.c index 0eb366c7804..a8040898b3b 100644 --- a/sys/dev/ic/midway.c +++ b/sys/dev/ic/midway.c @@ -1,4 +1,4 @@ -/* $OpenBSD: midway.c,v 1.21 1997/09/29 17:45:58 chuck Exp $ */ +/* $OpenBSD: midway.c,v 1.22 1998/10/20 23:31:06 deraadt Exp $ */ /* (sync'd to midway.c 1.68) */ /* @@ -1861,7 +1861,14 @@ again: goto dequeue_drop; } - if (launch.need > sc->txslot[chan].bfree) { + /* + * note: note that we cannot totally fill the circular buffer (i.e. + * we can't use up all of the remaining sc->txslot[chan].bfree free + * bytes) because that would cause the circular buffer read pointer + * to become equal to the write pointer, thus signaling 'empty buffer' + * to the hardware and stopping the transmitter. + */ + if (launch.need >= sc->txslot[chan].bfree) { EN_COUNT(sc->txoutspace); #ifdef EN_DEBUG printf("%s: tx%d: out of transmit space\n", sc->sc_dev.dv_xname, chan); -- cgit v1.2.3