On 8/9/2026 7:02 PM, Aleksandrs Vinarskis wrote:
> This series adds Embedded Controller (EC) driver for Dell XPS 13 9345.
> While EC appears to control most of device's peripherals, particular
> driver addresses power and thermal managment issues. Key operational
> principle involves initial thermistor constants configuration followed
> by a periodic reporting of these onboard thermistor values from across
> the motherboard to the EC. The latter then handles fan ramp-up/
> ramp-down internally. Suspend/Resume must be likewise propagated to EC
> for power management.
>
> The driver was developed primarily by analyzing ACPI DSDT's _DSM and
> i2c dumps of communication between SoC and EC during various stages of
> operation (bootup, suspend, resume).
>
> With EC driver in place, the following issues are addressed:
> 1. Fans were not properly cooling the laptop, would kick in late and
> spin lazily, resulting in heavy throttling. With EC driver fans
> start sooner and hit high RPM under heavy load.
> 2. Fans were not stopping once SoC temperature dropped, they would keep
> slowly spinning irrespective of suspend and/or closed lid until the
> next powercycle. With EC driver shortly after SoC temperature drops,
> thermistors temperature drops, and fans ramp-down.
> 3. Keyboard and touch row backlight were not turning off during
> suspend - only lid close would power off the touch row. With EC
> driver behavior matches that of Windows, suspending device with lid
> open powers off the peripherals.
>
> As thermistor readout depends on pmic's ADCs, this series introduces
> EC driver and its schema, adds missing ADC to hamoa-pmics, and finally
> adds thermistor and EC nodes to x1e80100-dell-xps13-9345.dts.
>
> Additional findings:
> - Max fan speed depends on Dell's power mode settings, configurable in
> BIOS or using Windows app (relies on ACPI-WMI). It appears best
> cooling performance is achieved under 'Ultra Performance' profile.
> - When the said power mode is changed using Windows app, EC IRQ is
> triggered. Windows performs what appears to be thermistor contants
> readout, though its not obvious what it is used for.
> - Given similarities between Dell XPS 13 series (codename 'tributo')
> and Snapdragon-based Latitude, Inspiron ('thena'), including matching
> EC address and response to suspend/resume command the EC driver can
> be likely used for both, though in-depth testing on 'thena' is
> required.
>
Hi Alex,
> This series depends on QCOM SPMI PMIC5 Gen3 ADC [1], which was added to
> `linux-next` for v7.1, but must be picked if this series to be backported.
>
> [1]
> https://lore.kernel.org/all/[email protected]/
>
Just a minor point - this link points to V11 of the patch series, but please
note
V10 was the version of the series actually picked in the kernel. The difference
between
V10 and V11 is minimal though.
Thanks,
Jishnu
> Signed-off-by: Aleksandrs Vinarskis <[email protected]>
> ---
> Changes in v4:
