[PATCH 2/2] HID: i2c-hid: Do not bind to CHPN0001 touchscreen

[Hans de Goede <hdegoede@redhat.com>]

The CHPN0001 ACPI device has a _CID of PNP0C50 but is not HID compatible,
it uses its own protocol which is handled by the chipone_icn8318 driver.

If the i2c_hid_driver's probe functon gets called it will fail with a
"hid_descr_cmd failed" error.

Worse, after the probe failure the i2c / ACPI core code will put the ACPI
device in D3 state and when the chipone_icn8318 driver then loads the
device is put back in D0 state, executing its PS0 ACPI method, which
resets the controller, causing the controller to loose its firmware
which was loaded by the BIOS. The chipone_icn8318 driver has a workaround
for this, but that requires it to be the only (or the first) driver to
probe the device.

This commit adds a match callback and returns -ENODEV for i2c_client-s
with a CHPN0001 ACPI device id, so that the probe function never gets
called, fixing the controller losing its firmware.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
-Use the new i2c_driver match callback to only filter out the CHPN0001
 ACPI device, rather then use acpi_dev_present in probe and not
 registering the driver at all when the system has a CHPN0001 device
---
 drivers/hid/i2c-hid/i2c-hid.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index 046f692fd0a2..79bed9afc388 100644
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -891,6 +891,26 @@ static void i2c_hid_acpi_fix_up_power(struct device *dev)
 		acpi_device_fix_up_power(adev);
 }
 
+static const struct acpi_device_id i2c_hid_acpi_blacklist[] = {
+	/*
+	 * The CHPN0001 ACPI device has a _CID of PNP0C50 but is not HID
+	 * compatible, just probing it puts the device in an unusable state due
+	 * to it also have ACPI power management issues.
+	 */
+	{"CHPN0001", 0 },
+	{ },
+};
+
+static int i2c_hid_match(struct i2c_client *client)
+{
+	struct acpi_device *adev = ACPI_COMPANION(&client->dev);
+
+	if (adev && acpi_match_device_ids(adev, i2c_hid_acpi_blacklist) == 0)
+		return -ENODEV;
+
+	return 0;
+}
+
 static const struct acpi_device_id i2c_hid_acpi_match[] = {
 	{"ACPI0C50", 0 },
 	{"PNP0C50", 0 },
@@ -905,6 +925,7 @@ static inline int i2c_hid_acpi_pdata(struct i2c_client *client,
 }
 
 static inline void i2c_hid_acpi_fix_up_power(struct device *dev) {}
+static int i2c_hid_match(struct i2c_client *client) { return 0; }
 #endif
 
 #ifdef CONFIG_OF
@@ -1255,6 +1276,7 @@ static struct i2c_driver i2c_hid_driver = {
 		.of_match_table = of_match_ptr(i2c_hid_of_match),
 	},
 
+	.match		= i2c_hid_match,
 	.probe		= i2c_hid_probe,
 	.remove		= i2c_hid_remove,
 	.shutdown	= i2c_hid_shutdown,
-- 
2.13.0