[PATCH 3/5] at91udc: fix recursive poll()

[Cerrato Renaud]

I noticed some weird behavior using DFU gadget on AT91SAM9260 which worked 1 of 10 times. The bug was due to the usb_gadget_poll() being called while the previous call was still in progress : some USB calls may takes a lot of time (ex : DFU erase-then-write), resulting in the poller to be triggered again while still in the poll() function.

This patch adds a poll lock to the AT91 UDC driver.

Signed-off-by: Cerrato Renaud <r.cerrato at til-technologies.fr>
---
 drivers/usb/gadget/at91_udc.c |   14 ++++++++------
 drivers/usb/gadget/at91_udc.h |    1 +
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/gadget/at91_udc.c b/drivers/usb/gadget/at91_udc.c
index 0654038..8ae9119 100644
--- a/drivers/usb/gadget/at91_udc.c
+++ b/drivers/usb/gadget/at91_udc.c
@@ -1340,22 +1340,24 @@ int usb_gadget_poll(void)
     struct at91_udc    *udc = &controller;
     u32 value;
 
-    if (!udc->udp_baseaddr)
+    if (!udc->udp_baseaddr || udc->poll_lock)
         return 0;
 
+    udc->poll_lock = 1;
+
     value = gpio_get_value(udc->board.vbus_pin);
     value ^= udc->board.vbus_active_low;
-
-    if (!value) {
-        at91_update_vbus(udc, value);
-        return 0;
-    }
     at91_update_vbus(udc, value);
 
+    if (!value)
+        goto exit;
+
     value = at91_udp_read(udc, AT91_UDP_ISR) & (~(AT91_UDP_SOFINT));
     if (value)
         at91_udc_irq(udc);
 
+exit:
+    udc->poll_lock = 0;
     return value;
 }
 
diff --git a/drivers/usb/gadget/at91_udc.h b/drivers/usb/gadget/at91_udc.h
index e592cc5..51145a9 100644
--- a/drivers/usb/gadget/at91_udc.h
+++ b/drivers/usb/gadget/at91_udc.h
@@ -127,6 +127,7 @@ struct at91_udc {
     unsigned            wait_for_config_ack:1;
     unsigned            selfpowered:1;
     unsigned            active_suspend:1;
+    unsigned            poll_lock:1;
     u8                addr;
     u32                gpio_vbus_val;
     struct at91_udc_data        board;
-- 
1.7.2.5