65299e8bfb
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. 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> Link: https://lore.kernel.org/r/20210405202756.16830-1-hdegoede@redhat.com Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.