Re: [PATCH 2/4] platform: arm64: dell-xps-ec: new driver

[Konrad Dybcio]

On 4/1/26 9:33 AM, Aleksandrs Vinarskis wrote:
> 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.

[...]

> +/*
> + * Format:
> + * - header/unknown (2 bytes)
> + * - per-thermistor entries (3 bytes): thermistor_id, param1, param2
> + */
> +static const u8 dell_xps_ec_thermistor_profile[] = {
> +	0xff, 0x54,

This is super wishful thinking, but 0x54 is ASCII 'T', perhaps for
"Thermistor" or "Temp"?

> +static int dell_xps_ec_suspend_cmd(struct dell_xps_ec *ec, bool suspend)
> +{
> +	u8 buf[DELL_XPS_EC_SUSPEND_MSG_LEN] = {};
> +	int ret;
> +
> +	buf[0] = DELL_XPS_EC_SUSPEND_CMD;
> +	buf[1] = suspend ? 0x01 : 0x00;
> +	/* bytes 2..63 remain zero */

buf[1] = suspend

(since it's a boolean argument)


[...]

> +	schedule_delayed_work(&ec->temp_work,
> +			      msecs_to_jiffies(DELL_XPS_EC_TEMP_INTERVAL_MS));
> +	dev_info(dev, "Started periodic temperature reporting to EC every %d ms\n",
> +		 DELL_XPS_EC_TEMP_INTERVAL_MS);

dev_dbg()?


> +
> +	/* Request IRQ for EC events */
> +	ret = devm_request_threaded_irq(dev, client->irq, NULL,
> +					dell_xps_ec_irq_handler,
> +					IRQF_ONESHOT, dev_name(dev), ec);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to request IRQ\n");
> +
> +	return 0;
> +}
> +
> +/*
> + * Notify EC of suspend
> + *
> + * This will:
> + * - Ramp down the fans
> + * - Cut power to display/trackpad/keyboard/touch row
> + * - Periodically (?) power them back, such that wake-up source still works

FWIW

https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/modern-standby-firmware-notifications

Konrad