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Date:      Sat, 18 Nov 2017 20:38:05 +0000 (UTC)
From:      Emmanuel Vadot <manu@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r325977 - head/sys/arm/allwinner
Message-ID:  <201711182038.vAIKc5rr017618@repo.freebsd.org>
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Author: manu
Date: Sat Nov 18 20:38:05 2017
New Revision: 325977
URL: https://svnweb.freebsd.org/changeset/base/325977

Log:
  if_awg: only request completion interrupt on the last descriptor of a tx frame
  
  The hardware will not issue a completion interrupt for a descriptor
  with TX_INT_CTL set if it doesn't also have TX_LAST_DESC set.
  
  Submitted by:	 Guy Yur <guyyur_gmail.com>
  Differential Revision:	https://reviews.freebsd.org/D13029

Modified:
  head/sys/arm/allwinner/if_awg.c

Modified: head/sys/arm/allwinner/if_awg.c
==============================================================================
--- head/sys/arm/allwinner/if_awg.c	Sat Nov 18 20:32:09 2017	(r325976)
+++ head/sys/arm/allwinner/if_awg.c	Sat Nov 18 20:38:05 2017	(r325977)
@@ -169,6 +169,7 @@ struct awg_txring {
 	bus_dma_tag_t		buf_tag;
 	struct awg_bufmap	buf_map[TX_DESC_COUNT];
 	u_int			cur, next, queued;
+	u_int			segs;
 };
 
 struct awg_rxring {
@@ -399,8 +400,6 @@ awg_setup_txdesc(struct awg_softc *sc, int index, int 
 	} else {
 		status = TX_DESC_CTL;
 		size = flags | len;
-		if ((index & (awg_tx_interval - 1)) == 0)
-			size |= TX_INT_CTL;
 		++sc->tx.queued;
 	}
 
@@ -449,8 +448,18 @@ awg_setup_txbuf(struct awg_softc *sc, int index, struc
 
 	for (cur = index, i = 0; i < nsegs; i++) {
 		sc->tx.buf_map[cur].mbuf = (i == 0 ? m : NULL);
-		if (i == nsegs - 1)
+		sc->tx.segs++;
+		if (i == nsegs - 1) {
 			flags |= TX_LAST_DESC;
+			/*
+			 * Can only request TX completion
+			 * interrupt on last descriptor.
+			 */
+			if (sc->tx.segs >= awg_tx_interval) {
+				sc->tx.segs = 0;
+				flags |= TX_INT_CTL;
+			}
+		}
 		awg_setup_txdesc(sc, cur, flags, segs[i].ds_addr,
 		    segs[i].ds_len);
 		flags &= ~TX_FIR_DESC;

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