Roger from SUSE reported the touchpad on Lenovo yoga2 crush sometimes.
He found that rmmod/modprobe elan_i2c will recover the issue.
He add the workaround on SUSE and solve the problem.
Recently, the workaround fails in kernel 4.20 becasue IRQ mismatch.
genirq: Flags mismatch irq 0. 00002002 (ELAN0600:00) vs. 00015a00 (timer)
I can't reproduce the issue in SUSE with the same kernel.
And it's a 5 years old laptop, ELAN can't find the module for testing.
Instead of IRQ debugging IRQ, I tried another approach.
I added i2c_reset in sysfs to avoid IRQ requesting in probe.

Signed-off-by: KT Liao <kt.l...@emc.com.tw>
Acked-by: Roger Whittaker <roger.whitta...@suse.com>
---
 drivers/input/mouse/elan_i2c_core.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/input/mouse/elan_i2c_core.c 
b/drivers/input/mouse/elan_i2c_core.c
index 2690a4b..388b1f0 100644
--- a/drivers/input/mouse/elan_i2c_core.c
+++ b/drivers/input/mouse/elan_i2c_core.c
@@ -670,6 +670,29 @@ static ssize_t calibrate_store(struct device *dev,
        return retval ?: count;
 }
 
+static ssize_t i2c_reset_store(struct device *dev,
+                              struct device_attribute *attr,
+                              const char *buf, size_t count)
+{
+       struct i2c_client *client = to_i2c_client(dev);
+       struct elan_tp_data *data = i2c_get_clientdata(client);
+       int retval;
+
+       retval = mutex_lock_interruptible(&data->sysfs_mutex);
+       if (retval)
+               return retval;
+
+       disable_irq(client->irq);
+
+       retval = elan_initialize(data);
+       if (retval)
+               dev_err(dev, "failed to re-initialize touchpad: %d\n", retval);
+
+       enable_irq(client->irq);
+       mutex_unlock(&data->sysfs_mutex);
+       return retval ?: count;
+}
+
 static ssize_t elan_sysfs_read_mode(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
@@ -702,6 +725,7 @@ static DEVICE_ATTR(mode, S_IRUGO, elan_sysfs_read_mode, 
NULL);
 static DEVICE_ATTR(update_fw, S_IWUSR, NULL, elan_sysfs_update_fw);
 
 static DEVICE_ATTR_WO(calibrate);
+static DEVICE_ATTR_WO(i2c_reset);
 
 static struct attribute *elan_sysfs_entries[] = {
        &dev_attr_product_id.attr,
@@ -710,6 +734,7 @@ static struct attribute *elan_sysfs_entries[] = {
        &dev_attr_iap_version.attr,
        &dev_attr_fw_checksum.attr,
        &dev_attr_calibrate.attr,
+       &dev_attr_i2c_reset.attr,
        &dev_attr_mode.attr,
        &dev_attr_update_fw.attr,
        NULL,
-- 
2.7.4

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