linux-kernel - [PATCH] regmap: irq: clear status when disable irq

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Message-ID: <1381724633-29586-1-git-send-email-yizhang@marvell.com>
Date:	Mon, 14 Oct 2013 12:23:53 +0800
From:	Yi Zhang <yizhang@...vell.com>
To:	<broonie@...nel.org>
CC:	<yizhang@...vell.com>, <qiaozhou@...vell.com>,
	<zhangwm@...vell.com>, <yizhang.mrvl@...il.com>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH] regmap: irq: clear status when disable irq

clear the status bit if the mask register doesn't prevent
the chip level irq from being asserted

OR in the following sequence, there will be irq storm happens:
1) interrupt is triggered;
2) another thread disables it(the mask bit is set);
3) _Then_ the interrupt thread is not ACKed(the status bit is not cleared),
   and it's ignored;
4) if the irq is still asserted because of the uncleared status bit,
   the irq storm happens;

Change-Id: I371201f365c5a8470073a393068cfeb4e3d14a03
Signed-off-by: Yi Zhang <yizhang@...vell.com>
---
 drivers/base/regmap/regmap-irq.c |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
index d10456f..cd655b8 100644
--- a/drivers/base/regmap/regmap-irq.c
+++ b/drivers/base/regmap/regmap-irq.c
@@ -105,6 +105,27 @@ static void regmap_irq_sync_unlock(struct irq_data *data)
 					"Failed to sync wakes in %x: %d\n",
 					reg, ret);
 		}
+
+		if (!d->chip->init_ack_masked)
+			continue;
+
+		/* Ack masked but set interrupts */
+		reg = d->chip->status_base +
+			(i * map->reg_stride * d->irq_reg_stride);
+		ret = regmap_read(d->map, reg, &d->status_buf[i]);
+		if (ret != 0)
+			dev_err(d->map->dev, "Failed to read IRQ status: %d\n",
+				ret);
+
+		if (d->status_buf[i] && d->chip->ack_base) {
+			reg = d->chip->ack_base +
+				(i * map->reg_stride * d->irq_reg_stride);
+			ret = regmap_write(d->map, reg,
+					d->status_buf[i] & d->mask_buf[i]);
+			if (ret != 0)
+				dev_err(d->map->dev, "Failed to ack 0x%x: %d\n",
+					reg, ret);
+		}
 	}
 
 	if (d->chip->runtime_pm)
-- 
1.7.9.5

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