musb_gadget: Fix for spurious interrupts on endpoint zero.
There is a multi-year old bug in the MUSB hardware which is not documented.
It causes spurious interrupts and have various symptoms, like endless
"SetupEnd came in a wrong ep0stage" messages. The fix is taken from the
FreeBSD's musb driver.
How to reproduce:
For example issue clear-stall on a couple of endpoints very fast,
like one request per 125us. After a while the bug triggers and the
musb-chip becomes unusable until next re-enumeration.
Signed-off-by: Hans Petter Selasky <hps@bitfrost.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/musb/musb_gadget_ep0.c b/drivers/usb/musb/musb_gadget_ep0.c
index 9378b35..6a0d046 100644
--- a/drivers/usb/musb/musb_gadget_ep0.c
+++ b/drivers/usb/musb/musb_gadget_ep0.c
@@ -679,6 +679,14 @@
musb_readb(mbase, MUSB_FADDR),
decode_ep0stage(musb->ep0_state));
+ if (csr & MUSB_CSR0_P_DATAEND) {
+ /*
+ * If DATAEND is set we should not call the callback,
+ * hence the status stage is not complete.
+ */
+ return IRQ_HANDLED;
+ }
+
/* I sent a stall.. need to acknowledge it now.. */
if (csr & MUSB_CSR0_P_SENTSTALL) {
musb_writew(regs, MUSB_CSR0,