linux-kernel - [PATCH 11/20] mfd/tc3589x: fix random interrupt misses

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Date:	Fri, 3 Dec 2010 20:35:44 +0530
From:	Sundar Iyer <sundar.iyer@...ricsson.com>
To:	<linux-arm-kernel@...ts.infradead.org>,
	<dmitry.torokhov@...il.com>, <sameo@...ux.intel.com>,
	<ben-linux@...ff.org>
Cc:	<linux-input@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Sundar Iyer <sundar.iyer@...ricsson.com>
Subject: [PATCH 11/20] mfd/tc3589x: fix random interrupt misses

On the TC35892, a random delayed interrupt clear (GPIO IC) write locks up the
child interrupts. In such a case, the original interrupt is active and not yet
acknowledged. Re-check the IRQST bit for any pending interrupts and handle
those.

Signed-off-by: Sundar Iyer <sundar.iyer@...ricsson.com>
---
 drivers/mfd/tc3589x.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/tc3589x.c b/drivers/mfd/tc3589x.c
index 5672d56..e173f33 100644
--- a/drivers/mfd/tc3589x.c
+++ b/drivers/mfd/tc3589x.c
@@ -158,6 +158,7 @@ static irqreturn_t tc3589x_irq(int irq, void *data)
 	struct tc3589x *tc3589x = data;
 	int status;
 
+again:
 	status = tc3589x_reg_read(tc3589x, TC3589x_IRQST);
 	if (status < 0)
 		return IRQ_NONE;
@@ -172,9 +173,12 @@ static irqreturn_t tc3589x_irq(int irq, void *data)
 	/*
 	 * A dummy read or write (to any register) appears to be necessary to
 	 * have the last interrupt clear (for example, GPIO IC write) take
-	 * effect.
+	 * effect. In such a case, recheck for any interrupt which is still
+	 * pending.
 	 */
-	tc3589x_reg_read(tc3589x, TC3589x_IRQST);
+	status = tc3589x_reg_read(tc3589x, TC3589x_IRQST);
+	if (status)
+		goto again;
 
 	return IRQ_HANDLED;
 }
-- 
1.7.2.dirty

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