usbxhci: better approach to unstalling endpoint and fixup td ring

instead of guessing where the controllers dequeue pointer went,
stop the endpoint and then explicitely set te dequeue pointer to
the next write td position. that way we do not need to fix the cycle
bit in the td's and dont need to rely on if the controller
advanced the dequeue pointer after a stall or not.

add ctx and slot back pointers to ring.

1 files changed, 43 insertions, 72 deletions

diff --git a/sys/src/9/pc/usbxhci.c b/sys/src/9/pc/usbxhci.c
index 8b7983f34..45e502c91 100644
--- a/sys/src/9/pc/usbxhci.c
+++ b/sys/src/9/pc/usbxhci.c
@@ -159,6 +159,10 @@ struct Wait
 
 struct Ring
 {
+	int	id;
+
+	Slot	*slot;
+
 	u32int	*base;
 
 	u32int	size;
@@ -168,10 +172,8 @@ struct Ring
 	u32int	rp;
 	u32int	wp;
 
-	struct {
-		u32int	*r;
-		u32int	v;
-	}	doorbell;
+	u32int	*ctx;
+	u32int	*doorbell;
 
 	Wait	*pending;
 	Lock;
@@ -264,8 +266,10 @@ freering(Ring *r)
 static void
 initring(Ring *r, int shift)
 {
-	r->doorbell.v = 0;
-	r->doorbell.r = nil;
+	r->id = 0;
+	r->ctx = nil;
+	r->slot = nil;
+	r->doorbell = nil;
 	r->pending = nil;
 	r->shift = shift;
 	r->size = 1<<shift;
@@ -337,8 +341,8 @@ init(Hci *hp)
 	ctlr->setrptr(&ctlr->opr[DCBAAP], PADDR(ctlr->dcba));
 
 	initring(ctlr->cr, 8);		/* 256 entries */
-	ctlr->cr->doorbell.r = &ctlr->dba[0];
-	ctlr->cr->doorbell.v = 0;
+	ctlr->cr->doorbell = &ctlr->dba[0];
+	ctlr->cr->id = 0;
 	coherence();
 	ctlr->setrptr(&ctlr->opr[CRCR], PADDR(ctlr->cr[0].base) | 1);
 
@@ -464,7 +468,7 @@ static void
 kickring(Ring *r)
 {
 	coherence();
-	*r->doorbell.r = r->doorbell.v;
+	*r->doorbell = r->id;
 }
 
 static char*
@@ -742,8 +746,10 @@ initep(Ep *ep)
 	}
 	if(ep->mode != OREAD){
 		initring(io->ring[OWRITE] = &slot->epr[ep->nb*2-1], 8);
-		io->ring[OWRITE]->doorbell.r = &ctlr->dba[slot->id];
-		io->ring[OWRITE]->doorbell.v = ep->nb*2;
+		io->ring[OWRITE]->doorbell = &ctlr->dba[slot->id];
+		io->ring[OWRITE]->slot = slot;
+		io->ring[OWRITE]->ctx = &slot->obase[(ep->nb*2+0)*8<<ctlr->csz];
+		io->ring[OWRITE]->id = ep->nb*2;
 
 		w[1] |= 1 << ep->nb*2;
 		if(ep->nb*2 > slot->nep)
@@ -751,8 +757,10 @@ initep(Ep *ep)
 	}
 	if(ep->mode != OWRITE){
 		initring(io->ring[OREAD] = &slot->epr[ep->nb*2], 8);
-		io->ring[OREAD]->doorbell.r = &ctlr->dba[slot->id];
-		io->ring[OREAD]->doorbell.v = ep->nb*2+1;
+		io->ring[OREAD]->doorbell = &ctlr->dba[slot->id];
+		io->ring[OREAD]->slot = slot;
+		io->ring[OREAD]->ctx = &slot->obase[(ep->nb*2+1)*8<<ctlr->csz];
+		io->ring[OREAD]->id = ep->nb*2+1;
 
 		w[1] |= 2 << ep->nb*2;
 		if(ep->nb*2+1 > slot->nep)
@@ -849,8 +857,10 @@ epopen(Ep *ep)
 
 	/* allocate control ep 0 ring */
 	initring(io->ring[OWRITE] = &slot->epr[0], 8);
-	io->ring[OWRITE]->doorbell.r = &ctlr->dba[slot->id];
-	io->ring[OWRITE]->doorbell.v = 1;
+	io->ring[OWRITE]->doorbell = &ctlr->dba[slot->id];
+	io->ring[OWRITE]->slot = slot;
+	io->ring[OWRITE]->ctx = &slot->obase[8];
+	io->ring[OWRITE]->id = 1;
 	slot->nep = 1;
 
 	/* (input) control context */
@@ -905,60 +915,21 @@ epopen(Ep *ep)
 }
 
 static void
-resetring(Ring *r)
+unstall(Ring *r)
 {
-	ilock(r);
-	r->rp--;	/* assume previous td halted */
-	while((int)(r->wp - r->rp) > 0){
-		u32int *td = &r->base[4*(--r->wp & r->mask)];
-		td[0] = td[1] = td[2] = 0;
-		td[3] = (r->wp>>r->shift)&1;
+	u64int qp;
+
+	switch(r->ctx[0]&7){
+	case 2:
+	case 4:
+		ilock(r);
+		r->rp = r->wp;
+		qp = PADDR(&r->base[4*(r->wp & r->mask)]) | ((~r->wp>>r->shift) & 1);
+		iunlock(r);
+
+		ctlrcmd(r->slot->ctlr, CR_RESETEP | (r->id<<16) | (r->slot->id<<24), 0, 0, nil);
+		ctlrcmd(r->slot->ctlr, CR_SETTRDQP | (r->id<<16) | (r->slot->id<<24), 0, qp, nil);
 	}
-	iunlock(r);
-}
-
-static int
-epunstall(Ep *ep, int mode)
-{
-	Ctlr *ctlr;
-	Slot *slot;
-	Epio *io;
-	u32int *w;
-	int dci, ret;
-
-	ret = 0;
-	io = ep->aux;
-	slot = ep->dev->aux;
-	ctlr = slot->ctlr;
-
-	if(ep->nb == 0)
-		dci = 1;
-	else
-		dci = ep->nb*2;	
-
-	/* (output) ep context */
-	w = slot->obase;
-	w += dci*8<<ctlr->csz;
-	if(mode != OREAD && io->ring[OWRITE] != nil){
-		switch(w[0]&7){
-		case 2:
-		case 4:
-			resetring(io->ring[OWRITE]);
-			ctlrcmd(ctlr, CR_RESETEP | (dci<<16) | (slot->id<<24), 0, 0, nil);
-			ret++;
-		}
-	}
-	w += 8<<ctlr->csz, dci++;
-	if(mode != OWRITE && io->ring[OREAD] != nil){
-		switch(w[0]&7){
-		case 2:
-		case 4:
-			resetring(io->ring[OREAD]);
-			ctlrcmd(ctlr, CR_RESETEP | (dci<<16) | (slot->id<<24), 0, 0, nil);
-			ret++;
-		}
-	}
-	return ret;
 }
 
 static long
@@ -972,6 +943,7 @@ epread(Ep *ep, void *va, long n)
 
 	p = va;
 	io = ep->aux;
+
 	if(ep->ttype == Tctl){
 		qlock(io);
 		if(io->cb == nil || BLEN(io->cb) == 0){
@@ -1001,8 +973,8 @@ epread(Ep *ep, void *va, long n)
 		return n;
 	}
 
-	epunstall(ep, OREAD);
 	ring = io->ring[OREAD];
+	unstall(ring);
 	ilock(ring);
 	queuetd(ring, TR_NORMAL | 1<<16 | 1<<5, n, PADDR(p), ws);
 	iunlock(ring);
@@ -1028,6 +1000,7 @@ epwrite(Ep *ep, void *va, long n)
 
 	p = va;
 	io = ep->aux;
+
 	if(ep->ttype == Tctl){
 		int dir, len;
 
@@ -1059,8 +1032,8 @@ epwrite(Ep *ep, void *va, long n)
 			}
 		}
 
-		epunstall(ep, OWRITE);
 		ring = io->ring[OWRITE];
+		unstall(ring);
 		ilock(ring);
 		queuetd(ring, TR_SETUPSTAGE | (len > 0 ? 2+dir : 0)<<16 | 1<<6 | 1<<5, 8,
 			p[0] | p[1]<<8 | GET2(&p[2])<<16 |
@@ -1104,8 +1077,8 @@ epwrite(Ep *ep, void *va, long n)
 		return n;
 	}
 
-	epunstall(ep, OWRITE);
 	ring = io->ring[OWRITE];
+	unstall(ring);
 	ilock(ring);
 	queuetd(ring, TR_NORMAL | 1<<16 | 1<<5, n, PADDR(p), ws);
 	iunlock(ring);
@@ -1238,8 +1211,6 @@ reset(Hci *hp)
 	if(getconf("*nousbxhci"))
 		return -1;
 
-	fmtinstall(L'H', encodefmt);
-
 	scanpci();
 
 	/*