From: Nick Dyer <[email protected]>

The path of enabling the IRQ in the probe function is not safe in level
triggered operation, if it was already powered up and there is a message
waiting on the device (eg finger down) because the object table has not yet
been read. This forces the ISR into a hard loop.

Delay enabling the interrupt until it is first needed.

Signed-off-by: Nick Dyer <[email protected]>
(cherry picked from ndyer/linux/for-upstream commit 
64c9dadc4a3250a185baf06ab0f628be45d5d9a0)
[gdavis: Resolve forward port conflicts due to v4.14-rc1 commit
         8cc8446b9b62 ("Input: atmel_mxt_ts - use more managed
         resources") and applying upstream commit 96a938aa214e ("Input:
         atmel_mxt_ts - remove platform data support").]
Signed-off-by: George G. Davis <[email protected]>
Signed-off-by: Jiada Wang <[email protected]>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 40 +++++++++++++++---------
 1 file changed, 26 insertions(+), 14 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c 
b/drivers/input/touchscreen/atmel_mxt_ts.c
index 2bc80abcbd80..d3e1cd677aa7 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -1450,9 +1450,24 @@ static int mxt_acquire_irq(struct mxt_data *data)
 {
        int error;
 
-       enable_irq(data->irq);
+       if (!data->irq) {
+               error = devm_request_threaded_irq(&data->client->dev,
+                                                 data->client->irq,
+                                                 NULL, mxt_interrupt,
+                                                 IRQF_ONESHOT,
+                                                 data->client->name, data);
+               if (error) {
+                       dev_err(&data->client->dev, "Error requesting irq\n");
+                       return error;
+               }
+
+               /* Presence of data->irq means IRQ initialised */
+               data->irq = data->client->irq;
+       } else {
+               enable_irq(data->irq);
+       }
 
-       if (data->use_retrigen_workaround) {
+       if (data->object_table && data->use_retrigen_workaround) {
                error = mxt_process_messages_until_invalid(data);
                if (error)
                        return error;
@@ -3369,7 +3384,9 @@ static int mxt_load_fw(struct device *dev)
                        goto release_firmware;
        }
 
-       enable_irq(data->irq);
+       ret = mxt_acquire_irq(data);
+       if (ret)
+               goto release_firmware;
 
        /* Poll after 0.1s if no interrupt received */
        schedule_delayed_work(&data->flash->work, HZ / 10);
@@ -3769,7 +3786,6 @@ static int mxt_probe(struct i2c_client *client, const 
struct i2c_device_id *id)
                 client->adapter->nr, client->addr);
 
        data->client = client;
-       data->irq = client->irq;
        i2c_set_clientdata(client, data);
 
        init_completion(&data->chg_completion);
@@ -3797,26 +3813,22 @@ static int mxt_probe(struct i2c_client *client, const 
struct i2c_device_id *id)
                return error;
        }
 
-       error = devm_request_threaded_irq(&client->dev, client->irq,
-                                         NULL, mxt_interrupt, IRQF_ONESHOT,
-                                         client->name, data);
-       if (error) {
-               dev_err(&client->dev, "Failed to register interrupt\n");
-               return error;
-       }
-
        if (data->suspend_mode == MXT_SUSPEND_REGULATOR) {
+               error = mxt_acquire_irq(data);
+               if (error)
+                       return error;
+
                error = mxt_probe_regulators(data);
                if (error)
                        return error;
+
+               disable_irq(data->irq);
        } else if (data->reset_gpio) {
                msleep(MXT_RESET_GPIO_TIME);
                gpiod_set_value(data->reset_gpio, 1);
                msleep(MXT_RESET_INVALID_CHG);
        }
 
-       disable_irq(data->irq);
-
        error = sysfs_create_group(&client->dev.kobj, &mxt_fw_attr_group);
        if (error) {
                dev_err(&client->dev, "Failure %d creating fw sysfs group\n",
-- 
2.19.2

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