rapidio: fix hang on RapidIO doorbell queue full condition

In fsl_rio_dbell_handler() the code currently simply acknowledges the QFI
queue full interrupt, but does nothing to resolve the queue full
condition.  Instead, it jumps to the end of the isr.  When a queue full
condition occurs, the isr is then re-entered immediately and continually,
forever.

The fix is to just fall through and read out current doorbell entries.

Signed-off-by: Thomas Taranowski <[email protected]>
Cc: Alexandre Bounine <[email protected]>
Cc: Kumar Gala <[email protected]>
Cc: Matt Porter <[email protected]>
Cc: Li Yang <[email protected]>
Cc: Thomas Moll <[email protected]>
Cc: Micha Nelissen <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Grant Likely <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

arch/powerpc/sysdev/fsl_rio.c

@@ -973,7 +973,6 @@ fsl_rio_dbell_handler(int irq, void *dev_instance)
 	if (dsr & DOORBELL_DSR_QFI) {
 		pr_info("RIO: doorbell queue full\n");
 		out_be32(&priv->msg_regs->dsr, DOORBELL_DSR_QFI);
-		goto out;
 	}
 
 	/* XXX Need to check/dispatch until queue empty */