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Subject[PATCH v1 41/63] Input: touchscreen: Atmel: Enable IRQ_DISABLE_UNLAZY flag for interrupt
Date
From: Bhuvanesh Surachari <bhuvanesh_surachari@mentor.com>

The de-/serializer driver has defined only irq_mask "ds90ub927_irq_mask" and
irq_unmask "ds90ub927_irq_unmask" callback functions. And de-/serializer
driver doesn't implement the irq_disable and irq_enable callback functions.
Hence inorder to invoke irq_mask callback function when disable_irq_nosync is
called the IRQ_DISABLE_UNLAZY interrupt flag should be set. If not the
disable_irq_nosync will just increment the depth field in the irq
descriptor only once as shown below.

disable_irq_nosync
__disable_irq_nosync
__disable_irq (desc->depth++)
irq_disable
if irq_disable present -----------> if IRQ_DISABLE_UNLAZYflag set
| no |
yes | yes |
| |
desc->irq_data.chip->irq_disable desc->irq_data.chip->irq_unmask
(ds90ub927_irq_mask)
disable_irq
__disable_irq_nosync
__disable_irq
(desc->depth++)
But the enable_irq will try to decrement the depth field twice which generates
the backtrace stating "Unbalanced enable for irq 293". This is because there is
no IRQ_DISABLE_UNLAZY flag check while calling irq_unmask callback function
of the "ds90ub927_irq_unmask" de-/serializer via enable_irq.

enable_irq
__enable_irq (desc->depth--)
irq_enable
if irq_enable present -------------> desc->irq_data.chip->irq_unmask
| no (ds90ub927_irq_unmask)
yes | enable_irq
| __enable_irq (desc->depth--)
(desc->irq_data.chip->irq_enable)

Signed-off-by: Bhuvanesh Surachari <bhuvanesh_surachari@mentor.com>
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
---
drivers/input/touchscreen/atmel_mxt_ts.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index bc94adec6631..c6ba061098c0 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -4349,6 +4349,8 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
snprintf(data->phys, sizeof(data->phys), "i2c-%u-%04x/input0",
client->adapter->nr, client->addr);

+ irq_set_status_flags(client->irq, IRQ_DISABLE_UNLAZY);
+
data->client = client;
i2c_set_clientdata(client, data);

@@ -4434,6 +4436,8 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
sysfs_remove_link(&client->dev.kobj, "reset");
gpiod_unexport(data->reset_gpio);
}
+ if (data->irq)
+ irq_clear_status_flags(data->irq, IRQ_DISABLE_UNLAZY);
return error;
}

@@ -4449,6 +4453,8 @@ static int mxt_remove(struct i2c_client *client)
}
mxt_debug_msg_remove(data);
mxt_sysfs_remove(data);
+ if (data->irq)
+ irq_clear_status_flags(data->irq, IRQ_DISABLE_UNLAZY);
mxt_free_input_device(data);
mxt_free_object_table(data);

--
2.19.2
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