Re: [PATCH resend] Input: elants_i2c - Do not bind to i2c-hid compatible ACPI instantiated devices

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Mon, Apr 05, 2021 at 10:27:56PM +0200, Hans de Goede wrote:
> Several users have been reporting that elants_i2c gives several errors
> during probe and that their touchscreen does not work on their Lenovo AMD
> based laptops with a touchscreen with a ELAN0001 ACPI hardware-id:
> 
> [    0.550596] elants_i2c i2c-ELAN0001:00: i2c-ELAN0001:00 supply vcc33 not found, using dummy regulator
> [    0.551836] elants_i2c i2c-ELAN0001:00: i2c-ELAN0001:00 supply vccio not found, using dummy regulator
> [    0.560932] elants_i2c i2c-ELAN0001:00: elants_i2c_send failed (77 77 77 77): -121
> [    0.562427] elants_i2c i2c-ELAN0001:00: software reset failed: -121
> [    0.595925] elants_i2c i2c-ELAN0001:00: elants_i2c_send failed (77 77 77 77): -121
> [    0.597974] elants_i2c i2c-ELAN0001:00: software reset failed: -121
> [    0.621893] elants_i2c i2c-ELAN0001:00: elants_i2c_send failed (77 77 77 77): -121
> [    0.622504] elants_i2c i2c-ELAN0001:00: software reset failed: -121
> [    0.632650] elants_i2c i2c-ELAN0001:00: elants_i2c_send failed (4d 61 69 6e): -121
> [    0.634256] elants_i2c i2c-ELAN0001:00: boot failed: -121
> [    0.699212] elants_i2c i2c-ELAN0001:00: invalid 'hello' packet: 00 00 ff ff
> [    1.630506] elants_i2c i2c-ELAN0001:00: Failed to read fw id: -121
> [    1.645508] elants_i2c i2c-ELAN0001:00: unknown packet 00 00 ff ff
> 
> Despite these errors, the elants_i2c driver stays bound to the device
> (it returns 0 from its probe method despite the errors), blocking the
> i2c-hid driver from binding.
> 
> Manually unbinding the elants_i2c driver and binding the i2c-hid driver
> makes the touchscreen work.
> 
> Check if the ACPI-fwnode for the touchscreen contains one of the i2c-hid
> compatiblity-id strings and if it has the I2C-HID spec's DSM to get the
> HID descriptor address, If it has both then make elants_i2c not bind,
> so that the i2c-hid driver can bind.
> 
> This assumes that non of the (older) elan touchscreens which actually
> need the elants_i2c driver falsely advertise an i2c-hid compatiblity-id
> + DSM in their ACPI-fwnodes. If some of them actually do have this
> false advertising, then this change may lead to regressions.
> 
> While at it also drop the unnecessary DEVICE_NAME prefixing of the
> "I2C check functionality error", dev_err already outputs the driver-name.
> 
> Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207759
> Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Applied, thank you.

-- 
Dmitry