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Date:      Mon, 22 Oct 2018 23:06:24 +0000 (UTC)
From:      Navdeep Parhar <np@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r339626 - head/sys/dev/cxgbe
Message-ID:  <201810222306.w9MN6Oiu080382@repo.freebsd.org>
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Author: np
Date: Mon Oct 22 23:06:23 2018
New Revision: 339626
URL: https://svnweb.freebsd.org/changeset/base/339626

Log:
  cxgbe(4): Use automatic cidx updates with ofld and ctrl queues.
  
  The bits that explicitly request cidx updates do not work reliably with
  all possible WRs that can be sent over the queue.  The F_FW_WR_EQUIQ
  requests that still remain may also have to be replaced with explicit
  credit flush WRs in the future.
  
  MFC after:	2 days
  Sponsored by:	Chelsio Communications

Modified:
  head/sys/dev/cxgbe/t4_sge.c

Modified: head/sys/dev/cxgbe/t4_sge.c
==============================================================================
--- head/sys/dev/cxgbe/t4_sge.c	Mon Oct 22 22:24:32 2018	(r339625)
+++ head/sys/dev/cxgbe/t4_sge.c	Mon Oct 22 23:06:23 2018	(r339626)
@@ -2089,12 +2089,13 @@ drain_wrq_wr_list(struct adapter *sc, struct sge_wrq *
 
 		if (available < eq->sidx / 4 &&
 		    atomic_cmpset_int(&eq->equiq, 0, 1)) {
+				/*
+				 * XXX: This is not 100% reliable with some
+				 * types of WRs.  But this is a very unusual
+				 * situation for an ofld/ctrl queue anyway.
+				 */
 			dst->equiq_to_len16 |= htobe32(F_FW_WR_EQUIQ |
 			    F_FW_WR_EQUEQ);
-			eq->equeqidx = eq->pidx;
-		} else if (IDXDIFF(eq->pidx, eq->equeqidx, eq->sidx) >= 32) {
-			dst->equiq_to_len16 |= htobe32(F_FW_WR_EQUEQ);
-			eq->equeqidx = eq->pidx;
 		}
 
 		dbdiff += n;
@@ -2644,12 +2645,13 @@ commit_wrq_wr(struct sge_wrq *wrq, void *w, struct wrq
 			available = IDXDIFF(eq->cidx, eq->pidx, eq->sidx) - 1;
 			if (available < eq->sidx / 4 &&
 			    atomic_cmpset_int(&eq->equiq, 0, 1)) {
+				/*
+				 * XXX: This is not 100% reliable with some
+				 * types of WRs.  But this is a very unusual
+				 * situation for an ofld/ctrl queue anyway.
+				 */
 				dst->equiq_to_len16 |= htobe32(F_FW_WR_EQUIQ |
 				    F_FW_WR_EQUEQ);
-				eq->equeqidx = pidx;
-			} else if (IDXDIFF(eq->pidx, eq->equeqidx, eq->sidx) >= 32) {
-				dst->equiq_to_len16 |= htobe32(F_FW_WR_EQUEQ);
-				eq->equeqidx = pidx;
 			}
 
 			ring_eq_db(wrq->adapter, eq, ndesc);
@@ -3584,6 +3586,23 @@ free_nm_txq(struct vi_info *vi, struct sge_nm_txq *nm_
 }
 #endif
 
+/*
+ * Returns a reasonable automatic cidx flush threshold for a given queue size.
+ */
+static u_int
+qsize_to_fthresh(int qsize)
+{
+	u_int fthresh;
+
+	while (!powerof2(qsize))
+		qsize++;
+	fthresh = ilog2(qsize);
+	if (fthresh > X_CIDXFLUSHTHRESH_128)
+		fthresh = X_CIDXFLUSHTHRESH_128;
+
+	return (fthresh);
+}
+
 static int
 ctrl_eq_alloc(struct adapter *sc, struct sge_eq *eq)
 {
@@ -3607,7 +3626,7 @@ ctrl_eq_alloc(struct adapter *sc, struct sge_eq *eq)
 	c.dcaen_to_eqsize =
 	    htobe32(V_FW_EQ_CTRL_CMD_FBMIN(X_FETCHBURSTMIN_64B) |
 		V_FW_EQ_CTRL_CMD_FBMAX(X_FETCHBURSTMAX_512B) |
-		V_FW_EQ_CTRL_CMD_CIDXFTHRESH(X_CIDXFLUSHTHRESH_32) |
+		V_FW_EQ_CTRL_CMD_CIDXFTHRESH(qsize_to_fthresh(qsize)) |
 		V_FW_EQ_CTRL_CMD_EQSIZE(qsize));
 	c.eqaddr = htobe64(eq->ba);
 
@@ -3689,12 +3708,13 @@ ofld_eq_alloc(struct adapter *sc, struct vi_info *vi, 
 	c.alloc_to_len16 = htonl(F_FW_EQ_OFLD_CMD_ALLOC |
 	    F_FW_EQ_OFLD_CMD_EQSTART | FW_LEN16(c));
 	c.fetchszm_to_iqid =
-		htonl(V_FW_EQ_OFLD_CMD_HOSTFCMODE(X_HOSTFCMODE_NONE) |
+		htonl(V_FW_EQ_OFLD_CMD_HOSTFCMODE(X_HOSTFCMODE_STATUS_PAGE) |
 		    V_FW_EQ_OFLD_CMD_PCIECHN(eq->tx_chan) |
 		    F_FW_EQ_OFLD_CMD_FETCHRO | V_FW_EQ_OFLD_CMD_IQID(eq->iqid));
 	c.dcaen_to_eqsize =
 	    htobe32(V_FW_EQ_OFLD_CMD_FBMIN(X_FETCHBURSTMIN_64B) |
 		V_FW_EQ_OFLD_CMD_FBMAX(X_FETCHBURSTMAX_512B) |
+		V_FW_EQ_OFLD_CMD_CIDXFTHRESH(qsize_to_fthresh(qsize)) |
 		V_FW_EQ_OFLD_CMD_EQSIZE(qsize));
 	c.eqaddr = htobe64(eq->ba);
 
@@ -3732,8 +3752,9 @@ alloc_eq(struct adapter *sc, struct vi_info *vi, struc
 	if (rc)
 		return (rc);
 
-	eq->pidx = eq->cidx = 0;
-	eq->equeqidx = eq->dbidx = 0;
+	eq->pidx = eq->cidx = eq->dbidx = 0;
+	/* Note that equeqidx is not used with sge_wrq (OFLD/CTRL) queues. */
+	eq->equeqidx = 0;
 	eq->doorbells = sc->doorbells;
 
 	switch (eq->flags & EQ_TYPEMASK) {

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