[PATCH] spufs: fix context-switch decrementer code

[Arnd Bergmann <arnd.bergmann@de.ibm.com>]

From: Jordi Caubet <jordi_caubet@es.ibm.com>

We found that when the 'decrementer' is saved, the PPE saves the current
time 'csa->suspend_time'. When restoring the 'decrementer', (Step 34)
decrementer seems to be adjusted with the number of cycles th= at a spu
thread has not been running.

In that code it is missing a substract ('-') because 'delta_time' is
assigned a not substracted(see bellow).

Acked-by: Mark Nutter <mnutter@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>

---

Index: linus-2.6/arch/powerpc/platforms/cell/spufs/switch.c
===================================================================
--- linus-2.6.orig/arch/powerpc/platforms/cell/spufs/switch.c
+++ linus-2.6/arch/powerpc/platforms/cell/spufs/switch.c
@@ -1299,7 +1299,7 @@ static inline void setup_decr(struct spu
 		cycles_t resume_time = get_cycles();
 		cycles_t delta_time = resume_time - csa->suspend_time;
 
-		csa->lscsa->decr.slot[0] = delta_time;
+		csa->lscsa->decr.slot[0] -= delta_time;
 	}
 }