Thanks for helping me.

On Fri, Oct 15, 2021 at 02:32:13PM -0700, Dmitry Torokhov wrote:

quoted

# The touchscreen (ok):
i2c_designware AMDI0010:00: using lookup tables for GPIO lookup
i2c_designware AMDI0010:00: No GPIO consumer scl found
i2c i2c-0: adapter [Synopsys DesignWare I2C adapter] registered
i2c i2c-0: client [ELAN238E:00] registered with bus id i2c-ELAN238E:00
# The touchpad (not ok):
i2c_designware AMDI0010:01: using lookup tables for GPIO lookup
i2c_designware AMDI0010:01: No GPIO consumer scl found
i2c i2c-1: adapter [Synopsys DesignWare I2C adapter] registered

Since we do not see I2C client being registered in the case of touchpad
I'd start tracing drivers/i2c/i2c-core-acpi.c, functions
i2c_acpi_add_device() and i2c_acpi_get_info() to see where the failure
is. I guess the changes made ACPI descriptions not match with what Linux
expects.

I have enabled tracing via kernel parameters. Solely enabling i2c_acpi_add_device and i2c_acpi_get_info generates no output. Output for "ftrace=function ftrace_filter=i2c_acpi_*" is at [1]. I have also generated a version with the option func_stack_trace enabled, but I don't think that it worked, since the output has'nt changed that much: "ftrace=function ftrace_filter=i2c_acpi_* trace_options=print-parent,trace_printk,annotate,context-info,record-cmd,overwrite,irq-info,markers,function-trace,func_stack_trace" [2]. To correlate entries I'll also supply a dmesg buffer output [3] from the same boot.

While testing with different ftrace setups I've noticed that sometimes the touchscreen is not working. Looking at dmesg output [4] there seems to be an error while probing for it. As of [5]: "The duplicate WMI GUIDs are used for the binary MOF file of a _WDG entry in the ASL". To concentrate on the trackpad and not mix things up, I'd ignore these errors for the moment.

I'll continue reading through different docs of ftrace, to generate more usable output.

[1] https://op.xn--bimann-cta.de/bug/2021-10-16_trace.txt
[2] https://op.xn--bimann-cta.de/bug/2021-10-17_trace.txt
[3] https://op.xn--bimann-cta.de/bug/2021-10-17_dmesg.txt
[4] https://op.xn--bimann-cta.de/bug/touchscreen_errors.txt
[5] https://lkml.org/lkml/2017/12/8/914