tree 9ba48b0c3b45a28ca5682898cc18fdc34468bee8
parent 1e031ab31843d7b6e0ddc027ffde596f0b833b88
author Jim Broadus <jbroadus@gmail.com> 1550604627 -0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1557292903 +0200

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>