[src/trunk]: src/sys/dev/pci Be more aggressive in giving descriptors to the ...

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

details:   https://anonhg.NetBSD.org/src/rev/981b80f8737c
branches:  trunk
changeset: 533450:981b80f8737c
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Sun Jun 30 19:11:40 2002 +0000

description:
Be more aggressive in giving descriptors to the chip in the transmit
path: Instead of waiting for the if_snd queue to be drained before
giving ownership of the frist descriptor to the chip, do it after
sync'ing all the descriptors for a single packet.

diffstat:

 sys/dev/pci/if_sip.c |  36 +++++++++++++++++-------------------
 1 files changed, 17 insertions(+), 19 deletions(-)

diffs (85 lines):

diff -r 758336b1129d -r 981b80f8737c sys/dev/pci/if_sip.c
--- a/sys/dev/pci/if_sip.c      Sun Jun 30 18:52:21 2002 +0000
+++ b/sys/dev/pci/if_sip.c      Sun Jun 30 19:11:40 2002 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_sip.c,v 1.56 2002/06/30 18:52:21 thorpej Exp $      */
+/*     $NetBSD: if_sip.c,v 1.57 2002/06/30 19:11:40 thorpej Exp $      */
 
 /*-
  * Copyright (c) 2001, 2002 The NetBSD Foundation, Inc.
@@ -82,7 +82,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_sip.c,v 1.56 2002/06/30 18:52:21 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_sip.c,v 1.57 2002/06/30 19:11:40 thorpej Exp $");
 
 #include "bpfilter.h"
 
@@ -1025,7 +1025,11 @@
        struct mbuf *m0, *m;
        struct sip_txsoft *txs;
        bus_dmamap_t dmamap;
-       int error, firsttx, nexttx, lasttx, ofree, seg;
+       int error, nexttx, lasttx, seg;
+       int ofree = sc->sc_txfree;
+#if 0
+       int firsttx = sc->sc_txnext;
+#endif
 #ifdef DP83820
        u_int32_t extsts;
 #endif
@@ -1040,13 +1044,6 @@
                return;
 
        /*
-        * Remember the previous number of free descriptors and
-        * the first descriptor we'll use.
-        */
-       ofree = sc->sc_txfree;
-       firsttx = sc->sc_txnext;
-
-       /*
         * Loop through the send queue, setting up transmit descriptors
         * until we drain the queue, or use up all available transmit
         * descriptors.
@@ -1189,7 +1186,7 @@
                        sc->sc_txdescs[nexttx].sipd_bufptr =
                            htole32(dmamap->dm_segs[seg].ds_addr);
                        sc->sc_txdescs[nexttx].sipd_cmdsts =
-                           htole32((nexttx == firsttx ? 0 : CMDSTS_OWN) |
+                           htole32((nexttx == sc->sc_txnext ? 0 : CMDSTS_OWN) |
                            CMDSTS_MORE | dmamap->dm_segs[seg].ds_len);
 #ifdef DP83820
                        sc->sc_txdescs[nexttx].sipd_extsts = 0;
@@ -1259,6 +1256,15 @@
                    BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
 
                /*
+                * The entire packet is set up.  Give the first descrptor
+                * to the chip now.
+                */
+               sc->sc_txdescs[sc->sc_txnext].sipd_cmdsts |=
+                   htole32(CMDSTS_OWN);
+               SIP_CDTXSYNC(sc, sc->sc_txnext, 1,
+                   BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
+
+               /*
                 * Store a pointer to the packet so we can free it later,
                 * and remember what txdirty will be once the packet is
                 * done.
@@ -1290,14 +1296,6 @@
 
        if (sc->sc_txfree != ofree) {
                /*
-                * The entire packet chain is set up.  Give the
-                * first descrptor to the chip now.
-                */
-               sc->sc_txdescs[firsttx].sipd_cmdsts |= htole32(CMDSTS_OWN);
-               SIP_CDTXSYNC(sc, firsttx, 1,
-                   BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
-
-               /*
                 * Start the transmit process.  Note, the manual says
                 * that if there are no pending transmissions in the
                 * chip's internal queue (indicated by TXE being clear),