musb_gadget: fix unhandled endpoint 0 IRQs

The gadget EP0 code routinely ignores an interrupt at end of
the data phase because of musb_g_ep0_giveback() resetting the
state machine to "idle, waiting for SETUP" phase prematurely.

The driver also prematurely leaves the status phase on
receiving the SetupEnd interrupt.

As there were still unhandled endpoint 0 interrupts happening
from time to time after fixing these issues, there turned to
be yet another culprit: two distinct gadget states collapsed
into one.

The (missing) state that comes after STATUS IN/OUT states was
typically indiscernible from them since the corresponding
interrupts tend to happen within too little period of time
(due to only a zero-length status packet in between) and so
they got coalesced; yet this state is not the same as the next
one which is associated with the reception of a SETUP packet.

Adding this extra state seems to have fixed the rest of the
unhandled interrupts that generic_interrupt() and
davinci_interrupt() hid by faking their result and only
emitting a debug message -- so, stop doing that.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 43 insertions, 20 deletions

diff --git a/drivers/usb/musb/davinci.c b/drivers/usb/musb/davinci.c
index 10d11ab113ab..898b52fcff5d 100644
--- a/drivers/usb/musb/davinci.c
+++ b/drivers/usb/musb/davinci.c
@@ -372,12 +372,7 @@ static irqreturn_t davinci_interrupt(int irq, void *__hci)
 
         spin_unlock_irqrestore(&musb->lock, flags);
 
-        /* REVISIT we sometimes get unhandled IRQs
-         * (e.g. ep0).  not clear why...
-         */
-        if (retval != IRQ_HANDLED)
-                DBG(5, "unhandled? %08x\n", tmp);
-        return IRQ_HANDLED;
+        return retval;
 }
 
 int musb_platform_set_mode(struct musb *musb, u8 mode)
diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index 4000cf6d1e81..324459b619f7 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -1481,13 +1481,7 @@ static irqreturn_t generic_interrupt(int irq, void *__hci)
 
         spin_unlock_irqrestore(&musb->lock, flags);
 
-        /* REVISIT we sometimes get spurious IRQs on g_ep0
-         * not clear why...
-         */
-        if (retval != IRQ_HANDLED)
-                DBG(5, "spurious?\n");
-
-        return IRQ_HANDLED;
+        return retval;
 }
 
 #else
diff --git a/drivers/usb/musb/musb_core.h b/drivers/usb/musb/musb_core.h
index efb39b5e55b5..c2a776ee1947 100644
--- a/drivers/usb/musb/musb_core.h
+++ b/drivers/usb/musb/musb_core.h
@@ -171,7 +171,8 @@ enum musb_h_ep0_state {
 
 /* peripheral side ep0 states */
 enum musb_g_ep0_state {
-        MUSB_EP0_STAGE_SETUP,           /* idle, waiting for setup */
+        MUSB_EP0_STAGE_IDLE,            /* idle, waiting for SETUP */
+        MUSB_EP0_STAGE_SETUP,           /* received SETUP */
         MUSB_EP0_STAGE_TX,              /* IN data */
         MUSB_EP0_STAGE_RX,              /* OUT data */
         MUSB_EP0_STAGE_STATUSIN,        /* (after OUT data) */
diff --git a/drivers/usb/musb/musb_gadget_ep0.c b/drivers/usb/musb/musb_gadget_ep0.c
index 3f5e30ddfa27..40ed50ecedff 100644
--- a/drivers/usb/musb/musb_gadget_ep0.c
+++ b/drivers/usb/musb/musb_gadget_ep0.c
@@ -4,6 +4,7 @@
  * Copyright 2005 Mentor Graphics Corporation
  * Copyright (C) 2005-2006 by Texas Instruments
  * Copyright (C) 2006-2007 Nokia Corporation
+ * Copyright (C) 2008-2009 MontaVista Software, Inc. <source@mvista.com>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -58,7 +59,8 @@
 static char *decode_ep0stage(u8 stage)
 {
         switch (stage) {
-        case MUSB_EP0_STAGE_SETUP:      return "idle";
+        case MUSB_EP0_STAGE_IDLE:       return "idle";
+        case MUSB_EP0_STAGE_SETUP:      return "setup";
         case MUSB_EP0_STAGE_TX:         return "in";
         case MUSB_EP0_STAGE_RX:         return "out";
         case MUSB_EP0_STAGE_ACKWAIT:    return "wait";
@@ -628,7 +630,7 @@ irqreturn_t musb_g_ep0_irq(struct musb *musb)
                 musb_writew(regs, MUSB_CSR0,
                                 csr & ~MUSB_CSR0_P_SENTSTALL);
                 retval = IRQ_HANDLED;
-                musb->ep0_state = MUSB_EP0_STAGE_SETUP;
+                musb->ep0_state = MUSB_EP0_STAGE_IDLE;
                 csr = musb_readw(regs, MUSB_CSR0);
         }
 
@@ -636,7 +638,18 @@ irqreturn_t musb_g_ep0_irq(struct musb *musb)
         if (csr & MUSB_CSR0_P_SETUPEND) {
                 musb_writew(regs, MUSB_CSR0, MUSB_CSR0_P_SVDSETUPEND);
                 retval = IRQ_HANDLED;
-                musb->ep0_state = MUSB_EP0_STAGE_SETUP;
+                /* Transition into the early status phase */
+                switch (musb->ep0_state) {
+                case MUSB_EP0_STAGE_TX:
+                        musb->ep0_state = MUSB_EP0_STAGE_STATUSOUT;
+                        break;
+                case MUSB_EP0_STAGE_RX:
+                        musb->ep0_state = MUSB_EP0_STAGE_STATUSIN;
+                        break;
+                default:
+                        ERR("SetupEnd came in a wrong ep0stage %s",
+                            decode_ep0stage(musb->ep0_state));
+                }
                 csr = musb_readw(regs, MUSB_CSR0);
                 /* NOTE:  request may need completion */
         }
@@ -697,11 +710,31 @@ irqreturn_t musb_g_ep0_irq(struct musb *musb)
                         if (req)
                                 musb_g_ep0_giveback(musb, req);
                 }
+
+                /*
+                 * In case when several interrupts can get coalesced,
+                 * check to see if we've already received a SETUP packet...
+                 */
+                if (csr & MUSB_CSR0_RXPKTRDY)
+                        goto setup;
+
+                retval = IRQ_HANDLED;
+                musb->ep0_state = MUSB_EP0_STAGE_IDLE;
+                break;
+
+        case MUSB_EP0_STAGE_IDLE:
+                /*
+                 * This state is typically (but not always) indiscernible
+                 * from the status states since the corresponding interrupts
+                 * tend to happen within too little period of time (with only
+                 * a zero-length packet in between) and so get coalesced...
+                 */
                 retval = IRQ_HANDLED;
                 musb->ep0_state = MUSB_EP0_STAGE_SETUP;
                 /* FALLTHROUGH */
 
         case MUSB_EP0_STAGE_SETUP:
+setup:
                 if (csr & MUSB_CSR0_RXPKTRDY) {
                         struct usb_ctrlrequest  setup;
                         int                     handled = 0;
@@ -783,7 +816,7 @@ irqreturn_t musb_g_ep0_irq(struct musb *musb)
 stall:
                                 DBG(3, "stall (%d)\n", handled);
                                 musb->ackpend |= MUSB_CSR0_P_SENDSTALL;
-                                musb->ep0_state = MUSB_EP0_STAGE_SETUP;
+                                musb->ep0_state = MUSB_EP0_STAGE_IDLE;
 finish:
                                 musb_writew(regs, MUSB_CSR0,
                                                 musb->ackpend);
@@ -803,7 +836,7 @@ finish:
                 /* "can't happen" */
                 WARN_ON(1);
                 musb_writew(regs, MUSB_CSR0, MUSB_CSR0_P_SENDSTALL);
-                musb->ep0_state = MUSB_EP0_STAGE_SETUP;
+                musb->ep0_state = MUSB_EP0_STAGE_IDLE;
                 break;
         }
 
@@ -959,7 +992,7 @@ static int musb_g_ep0_halt(struct usb_ep *e, int value)
 
                 csr |= MUSB_CSR0_P_SENDSTALL;
                 musb_writew(regs, MUSB_CSR0, csr);
-                musb->ep0_state = MUSB_EP0_STAGE_SETUP;
+                musb->ep0_state = MUSB_EP0_STAGE_IDLE;
                 musb->ackpend = 0;
                 break;
         default: