Re: [Bluez-devel] RE: Rfcomm qualification

[Marcel Holtmann <marcel@rvs.uni-bielefeld.de>]

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Hi Max,

> >The session wide credits value is useless 
> No, it's not. 1.1 spec only mandates send PN for the _first_ DLC
> on that session. Which means that values negotiated in PN request are supposed 
> to be applied to the subsequent DLCs.  So we still need session wide settings.
> We just need to update them when we get PN req/rsp, which don't do.
> 
> Check this out:
> "
> 6.5.1 Initial DLC Negotiation
> The use of credit based flow control is a session characteristic. Thus, it has to
> be negotiated with the PN multiplexor control command (see Section 5.5.3)
> before the first DLC is established.
> After the first successful negotiation and DLC establishment, all DLCs will be
> flow controlled with this scheme. PN negotiation at subsequent DLC establish-ments
> is optional, but recommended, since it also establishes initial credit
> count values on both sides for both sides.
> "

memory malfunction ;) I thought it was a per dlc value.

The attached patch sets the default values for session and dlc credits
to zero and put in RFCOMM_MAX_CREDITS only if we receive a PN with 1.1
flow control.

What do you think?

Regards

Marcel


[-- Attachment #2: patch --]
[-- Type: text/x-patch, Size: 1558 bytes --]

diff -Nru a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
--- a/net/bluetooth/rfcomm/core.c	Thu Jul 31 02:41:29 2003
+++ b/net/bluetooth/rfcomm/core.c	Thu Jul 31 02:41:29 2003
@@ -202,7 +202,7 @@
 	d->mtu        = RFCOMM_DEFAULT_MTU;
 	d->v24_sig    = RFCOMM_V24_RTC | RFCOMM_V24_RTR | RFCOMM_V24_DV;
 
-	d->credits    = RFCOMM_MAX_CREDITS;
+	d->credits    = 0;
 	d->rx_credits = RFCOMM_DEFAULT_CREDITS;
 }
 
@@ -475,7 +475,7 @@
 	s->sock  = sock;
 
 	s->mtu     = RFCOMM_DEFAULT_MTU;
-	s->credits = RFCOMM_MAX_CREDITS;
+	s->credits = 0;
 	
 	list_add(&s->list, &session_list);
 
@@ -746,7 +746,7 @@
 	pn->ack_timer   = 0;
 	pn->max_retrans = 0;
 
-	if (d->credits) {
+	if (cr || d->credits) {
 		pn->flow_ctrl = cr ? 0xf0 : 0xe0;
 		pn->credits = RFCOMM_DEFAULT_CREDITS;
 	} else {
@@ -1135,11 +1135,15 @@
 
 static int rfcomm_apply_pn(struct rfcomm_dlc *d, int cr, struct rfcomm_pn *pn)
 {
+	struct rfcomm_session *s = d->session;
+
 	BT_DBG("dlc %p state %ld dlci %d mtu %d fc 0x%x credits %d", 
 			d, d->state, d->dlci, pn->mtu, pn->flow_ctrl, pn->credits);
 
 	if (cr) {
 		if (pn->flow_ctrl == 0xf0) {
+			s->credits = RFCOMM_MAX_CREDITS;
+			d->credits = s->credits;
 			d->tx_credits = pn->credits;
 		} else {
 			set_bit(RFCOMM_TX_THROTTLED, &d->flags);
@@ -1147,6 +1151,8 @@
 		}
 	} else {
 		if (pn->flow_ctrl == 0xe0) {
+			s->credits = RFCOMM_MAX_CREDITS;
+			d->credits = s->credits;
 			d->tx_credits = pn->credits;
 		} else {
 			set_bit(RFCOMM_TX_THROTTLED, &d->flags);