ARM: OMAP: Fix spurious interrupts when using timer match feature

The OMAP DMTIMERs can generate an interrupt when the timer counter value
matches the value stored in the timer's match register. When using this
feature spurious interrupts were seen, because the compare logic is being
enabled before the match value is loaded and according to the documentation
the match value must be loaded before the compare logic is enable.

The reset value for the timer counter and match registers is 0 and hence,
by enabling the compare logic before the actual match value is loaded a
spurious interrupt can be generated as the reset values match.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c
index f0a3c4c72a420a501834b89d1ef85fa75ff8c508..a38e8964c820fc3d0f8b9b10f1a29b84778757a1 100644 (file)
--- a/arch/arm/plat-omap/dmtimer.c
+++ b/arch/arm/plat-omap/dmtimer.c
@@ -584,8 +584,8 @@ int omap_dm_timer_set_match(struct omap_dm_timer *timer, int enable,
                l |= OMAP_TIMER_CTRL_CE;
        else
                l &= ~OMAP_TIMER_CTRL_CE;
-       omap_dm_timer_write_reg(timer, OMAP_TIMER_CTRL_REG, l);
        omap_dm_timer_write_reg(timer, OMAP_TIMER_MATCH_REG, match);
+       omap_dm_timer_write_reg(timer, OMAP_TIMER_CTRL_REG, l);
 
        /* Save the context */
        timer->context.tclr = l;