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

On Mon, 24 Jul 2017, Benjamin Tissoires wrote:

quoted

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 <redacted>
---
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

I like the v2 much more than the v1.

Reviewed-By: Benjamin Tissoires <redacted>

Wolfram,

what do we do with this patchset? I think it makes sense for both patches 
to go in via one tree.

Either I can take it through hid.git with your Ack for the first patch, or 
vice versa. Please let me know what you'd prefer.

Thanks,

-- 
Jiri Kosina
SUSE Labs