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From: jon-hunter@ti.com (Jon Hunter)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH V3 10/13] ARM: OMAP: Fix spurious interrupts when using timer match feature
Date: Mon, 12 Nov 2012 12:20:41 -0600	[thread overview]
Message-ID: <1352744444-2633-11-git-send-email-jon-hunter@ti.com> (raw)
In-Reply-To: <1352744444-2633-1-git-send-email-jon-hunter@ti.com>

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>
---
 arch/arm/plat-omap/dmtimer.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c
index f0a3c4c..a38e896 100644
--- 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;
-- 
1.7.9.5

  parent reply	other threads:[~2012-11-12 18:20 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-11-12 18:20 [PATCH V3 00/13] ARM: OMAP: DMTIMER fixes Jon Hunter
2012-11-12 18:20 ` [PATCH V3 01/13] ARM: OMAP: Add DMTIMER definitions for posted mode Jon Hunter
2012-11-12 18:20 ` [PATCH V3 02/13] ARM: OMAP3+: Implement timer workaround for errata i103 and i767 Jon Hunter
2012-11-12 18:20 ` [PATCH V3 03/13] ARM: OMAP: Fix timer posted mode support Jon Hunter
2012-11-12 18:20 ` [PATCH V3 04/13] ARM: OMAP3: Correct HWMOD DMTIMER SYSC register declarations Jon Hunter
2012-11-12 18:20 ` [PATCH V3 05/13] ARM: OMAP2/3: Define HWMOD software reset status for DMTIMERs Jon Hunter
2012-11-12 18:20 ` [PATCH V3 06/13] ARM: OMAP2+: Don't use __omap_dm_timer_reset() Jon Hunter
2012-11-12 18:20 ` [PATCH V3 07/13] ARM: OMAP: Fix dmtimer reset for timer1 Jon Hunter
2012-11-12 18:20 ` [PATCH V3 08/13] ARM: OMAP: Don't restore of DMTIMER TISTAT register Jon Hunter
2012-11-12 18:20 ` [PATCH V3 09/13] ARM: OMAP: Don't restore DMTIMER interrupt status register Jon Hunter
2012-11-12 18:20 ` Jon Hunter [this message]
2012-11-12 18:20 ` [PATCH V3 11/13] ARM: OMAP: Add dmtimer interrupt disable function Jon Hunter
2012-11-12 18:20 ` [PATCH V3 12/13] ARM: OMAP: Remove unnecessary call to clk_get() Jon Hunter
2012-11-12 18:20 ` [PATCH V3 13/13] ARM: OMAP: Remove __omap_dm_timer_set_source function Jon Hunter
2012-11-12 20:34 ` [PATCH V3 00/13] ARM: OMAP: DMTIMER fixes Tony Lindgren
2012-11-12 21:38   ` Jon Hunter

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