usb: musb: disable double buffering when it's broken

We know that blackfin doesn't support double
buffering feature as of today. So we add a
flag set by musb_platform_init() to forcefully
disable that feature.

Such flag is created and marked as deprecated
to force us to find a solution for the missing
double buffering support on blackfin.
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/musb/blackfin.c

@@ -404,6 +404,7 @@ static int bfin_musb_init(struct musb *musb)
 		musb->xceiv->set_power = bfin_musb_set_power;
 
 	musb->isr = blackfin_interrupt;
+	musb->double_buffer_not_ok = true;
 
 	return 0;
 }

drivers/usb/musb/musb_core.h

@@ -488,6 +488,18 @@ struct musb {
 	unsigned		set_address:1;
 	unsigned		test_mode:1;
 	unsigned		softconnect:1;
+	/*
+	 * FIXME: Remove this flag.
+	 *
+	 * This is only added to allow Blackfin to work
+	 * with current driver. For some unknown reason
+	 * Blackfin doesn't work with double buffering
+	 * and that's enabled by default.
+	 *
+	 * We added this flag to forcefully disable double
+	 * buffering until we get it working.
+	 */
+	unsigned                double_buffer_not_ok:1 __deprecated;
 
 	u8			address;
 	u8			test_mode_nr;

drivers/usb/musb/musb_gadget.c

@@ -989,7 +989,11 @@ static int musb_gadget_enable(struct usb_ep *ep,
 		/* Set TXMAXP with the FIFO size of the endpoint
 		 * to disable double buffering mode.
 		 */
-		musb_writew(regs, MUSB_TXMAXP, musb_ep->packet_sz | (musb_ep->hb_mult << 11));
+		if (musb->double_buffer_not_ok)
+			musb_writew(regs, MUSB_TXMAXP, hw_ep->max_packet_sz_tx);
+		else
+			musb_writew(regs, MUSB_TXMAXP, musb_ep->packet_sz
+					| (musb_ep->hb_mult << 11));
 
 		csr = MUSB_TXCSR_MODE | MUSB_TXCSR_CLRDATATOG;
 		if (musb_readw(regs, MUSB_TXCSR)
@@ -1025,7 +1029,11 @@ static int musb_gadget_enable(struct usb_ep *ep,
 		/* Set RXMAXP with the FIFO size of the endpoint
 		 * to disable double buffering mode.
 		 */
-		musb_writew(regs, MUSB_RXMAXP, musb_ep->packet_sz | (musb_ep->hb_mult << 11));
+		if (musb->double_buffer_not_ok)
+			musb_writew(regs, MUSB_RXMAXP, hw_ep->max_packet_sz_tx);
+		else
+			musb_writew(regs, MUSB_RXMAXP, musb_ep->packet_sz
+					| (musb_ep->hb_mult << 11));
 
 		/* force shared fifo to OUT-only mode */
 		if (hw_ep->is_shared_fifo) {

drivers/usb/musb/musb_host.c

@@ -609,7 +609,7 @@ musb_rx_reinit(struct musb *musb, struct musb_qh *qh, struct musb_hw_ep *ep)
 	/* Set RXMAXP with the FIFO size of the endpoint
 	 * to disable double buffer mode.
 	 */
-	if (musb->hwvers < MUSB_HWVERS_2000)
+	if (musb->double_buffer_not_ok)
 		musb_writew(ep->regs, MUSB_RXMAXP, ep->max_packet_sz_rx);
 	else
 		musb_writew(ep->regs, MUSB_RXMAXP,
@@ -784,14 +784,13 @@ static void musb_ep_program(struct musb *musb, u8 epnum,
 		/* protocol/endpoint/interval/NAKlimit */
 		if (epnum) {
 			musb_writeb(epio, MUSB_TXTYPE, qh->type_reg);
-			if (can_bulk_split(musb, qh->type))
+			if (musb->double_buffer_not_ok)
 				musb_writew(epio, MUSB_TXMAXP,
-					packet_sz
-					| ((hw_ep->max_packet_sz_tx /
-						packet_sz) - 1) << 11);
+						hw_ep->max_packet_sz_tx);
 			else
 				musb_writew(epio, MUSB_TXMAXP,
-					packet_sz);
+						qh->maxpacket |
+						((qh->hb_mult - 1) << 11));
 			musb_writeb(epio, MUSB_TXINTERVAL, qh->intv_reg);
 		} else {
 			musb_writeb(epio, MUSB_NAKLIMIT0, qh->intv_reg);