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Aleksandrs VinarskisandAbel Vesa
06f65b7224
Introduce EC driver for Dell XPS 13 9345 (codename 'tributo') which may
partially of fully compatible with Snapdragon-based Dell Latitude,
Inspiron ('thena'). Primary function of this driver is unblock EC's
thermal management, specifically to provide it with necessary
information to control device fans, peripherals power.
The driver was developed primarily by analyzing ACPI DSDT's _DSM and
i2c dumps of communication between SoC and EC. Changes to Windows
driver's behavior include increasing temperature feed loop from ~50ms
to 100ms here.
While Xps's EC is rather complex and controls practically all device
peripherals including touch row's brightness and special keys such as
mic mute, these do not go over this particular i2c interface.
Not yet implemented features:
- On lid-close IRQ event is registered. Windows performs what to
appears to be thermistor constants readout, though its not obvious
what it used for.
- According to ACPI's _DSM there is a method to readout fans' RPM.
- Initial thermistor constants were sniffed from Windows, these can be
likely fine tuned for better cooling performance.
- There is additional temperature reading that Windows sents to EC but
more rare than others, likely SoC T_j / TZ98 or TZ4. This is the only
thermal zone who's reading can exceed 115C without triggering thermal
shutdown.
- Given similarities between 'tributo' and 'thena' platforms, including
EC i2c address, driver can be potentially extended to support both.
Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
Link: https://patch.msgid.link/20260801-dell-xps-9345-ec-v3-2-9f4bdb5a5dad@vinarskis.com
Signed-off-by: Abel Vesa <abel.vesa@oss.qualcomm.com>