linux-kernel - [PATCH v2] regmap: irq: clear status when disable irq

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Date:	Tue, 15 Oct 2013 20:23:30 +0800
From:	Yi Zhang <yizhang@...vell.com>
To:	<broonie@...nel.org>
CC:	<yizhang@...vell.com>, <zhouqiao@...vell.com>,
	<zhangwm@...vell.com>, <yizhang.mrvl@...il.com>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v2] 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;

Signed-off-by: Yi Zhang <yizhang@...vell.com>
---
 drivers/base/regmap/regmap-irq.c |   27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
index d10456f..9b0148f 100644
--- a/drivers/base/regmap/regmap-irq.c
+++ b/drivers/base/regmap/regmap-irq.c
@@ -61,7 +61,7 @@ static void regmap_irq_sync_unlock(struct irq_data *data)
 {
 	struct regmap_irq_chip_data *d = irq_data_get_irq_chip_data(data);
 	struct regmap *map = d->map;
-	int i, ret;
+	int i, j, ret, bits_length;
 	u32 reg;
 
 	if (d->chip->runtime_pm) {
@@ -105,6 +105,31 @@ 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 all the masked interrupts uncondictionly,
+		 * OR if there is masked interrupt which hasn't been Acked,
+		 * it'll be ignored in irq handler, then may introduce irq storm
+		 */
+		if (d->chip->ack_base) {
+			reg = d->chip->ack_base +
+				(i * map->reg_stride * d->irq_reg_stride);
+
+			bits_length = d->map->format.val_bytes * BITS_PER_BYTE;
+			for (j = 0; j < bits_length; j++) {
+				if (!(d->mask_buf[i] & (0x1 << j))) {
+					ret = regmap_update_bits(d->map, reg,
+								 (0x1 << j), 0);
+					if (ret != 0)
+						dev_err(d->map->dev,
+							"Failed to ack 0x%x: %d\n",
+							reg, ret);
+				}
+			}
+			/* no need to sync status_buf, update in irq handler */
+		}
 	}
 
 	if (d->chip->runtime_pm)
-- 
1.7.9.5

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