i2c: Allow recovery of the initial IRQ by an I2C client device.

commit 93b6604c5a669d84e45fe5129294875bf82eb1ff upstream.

A previous change allowed I2C client devices to discover new IRQs upon
reprobe by clearing the IRQ in i2c_device_remove. However, if an IRQ was
assigned in i2c_new_device, that information is lost.

For example, the touchscreen and trackpad devices on a Dell Inspiron laptop
are I2C devices whose IRQs are defined by ACPI extended IRQ types. The
client device structures are initialized during an ACPI walk. After
removing the i2c_hid device, modprobe fails.

This change caches the initial IRQ value in i2c_new_device and then resets
the client device IRQ to the initial value in i2c_device_remove.

Fixes: 6f108dd70d30 ("i2c: Clear client->irq in i2c_device_remove")
Signed-off-by: Jim Broadus <jbroadus@gmail.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
[wsa: this is an easy to backport fix for the regression. We will
refactor the code to handle irq assignments better in general.]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 9a48173..6dd74cc 100644 (file)
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -430,7 +430,7 @@ static int i2c_device_remove(struct device *dev)
        dev_pm_clear_wake_irq(&client->dev);
        device_init_wakeup(&client->dev, false);
 
-       client->irq = 0;
+       client->irq = client->init_irq;
 
        return status;
 }
@@ -741,10 +741,11 @@ i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
        client->flags = info->flags;
        client->addr = info->addr;
 
-       client->irq = info->irq;
-       if (!client->irq)
-               client->irq = i2c_dev_irq_from_resources(info->resources,
+       client->init_irq = info->irq;
+       if (!client->init_irq)
+               client->init_irq = i2c_dev_irq_from_resources(info->resources,
                                                         info->num_resources);
+       client->irq = client->init_irq;
 
        strlcpy(client->name, info->type, sizeof(client->name));
 

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 65b4eae..7e74864 100644 (file)
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -333,6 +333,7 @@ struct i2c_client {
        char name[I2C_NAME_SIZE];
        struct i2c_adapter *adapter;    /* the adapter we sit on        */
        struct device dev;              /* the device structure         */
+       int init_irq;                   /* irq set at initialization    */
        int irq;                        /* irq issued by device         */
        struct list_head detected;
 #if IS_ENABLED(CONFIG_I2C_SLAVE)