[PATCH] regmap: irq: clear status when disable irq

[Yi Zhang <yizhang@marvell.com>]

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@marvell.com>
---
 drivers/base/regmap/regmap-irq.c |   26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
index d10456f..0784cf4 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 +105,30 @@ 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++) {
+				d->mask_buf[i] &= (0x1 << j);
+				if (!d->mask_buf[i])
+					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