linux-kernel - Re: [PATCH 2/3] power: supply: Add Acer Aspire 1 embedded controller driver

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Date:   Thu, 7 Dec 2023 20:24:53 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Nikita Travkin <nikita@...n.ru>,
        Sebastian Reichel <sre@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        cros-qcom-dts-watchers@...omium.org,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>
Cc:     linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 2/3] power: supply: Add Acer Aspire 1 embedded controller
 driver



On 12/7/23 12:20, Nikita Travkin wrote:
> Acer Aspire 1 is a Snapdragon 7c based laptop. It uses an embedded
> controller to control the charging and battery management, as well as to
> perform a set of misc functions.
> 
> Unfortunately, while all this functionality is implemented in ACPI, it's
> currently not possible to use ACPI to boot Linux on such Qualcomm
> devices. To allow Linux to still support the features provided by EC,
> this driver reimplments the relevant ACPI parts. This allows us to boot
> the laptop with Device Tree and retain all the features.
> 
> Signed-off-by: Nikita Travkin <nikita@...n.ru>
> ---
[...]

> +	case POWER_SUPPLY_PROP_CAPACITY:
> +		val->intval = le16_to_cpu(ddat.capacity_now) * 100
> +			      / le16_to_cpu(sdat.capacity_full);
It may be just my OCD and im not the maintainer here, but I'd do
/= here

[...]

> +	case POWER_SUPPLY_PROP_MODEL_NAME:
> +		if (sdat.model_id - 1 < ARRAY_SIZE(aspire_ec_psy_battery_model))
> +			val->strval = aspire_ec_psy_battery_model[sdat.model_id - 1];
> +		else
> +			val->strval = "Unknown";
Would it make sense to print the model_id that's absent from the LUT
here and similarly below?

> +		break;
> +
> +	case POWER_SUPPLY_PROP_MANUFACTURER:
> +		if (sdat.vendor_id - 3 < ARRAY_SIZE(aspire_ec_psy_battery_vendor))
> +			val->strval = aspire_ec_psy_battery_vendor[sdat.vendor_id - 3];
> +		else
> +			val->strval = "Unknown";
> +		break;
> +
> +	default:
> +		return -EINVAL;
> +	}
Another ocd trip, i'd add a newline before return

> +	return 0;
> +}
[...]

> +	/*
> +	 * The original ACPI firmware actually has a small sleep in the handler.
> +	 *
> +	 * It seems like in most cases it's not needed but when the device
> +	 * just exits suspend, our i2c driver has a brief time where data
> +	 * transfer is not possible yet. So this delay allows us to suppress
> +	 * quite a bunch of spurious error messages in dmesg. Thus it's kept.
Ouch.. do you think i2c-geni needs fixing on this part?

[...]

> +	switch (id) {
> +	case 0x0: /* No event */
> +		break;
Is this a NOP/watchdog sort of thing?

[...]

> +
> +static struct i2c_driver aspire_ec_driver = {
> +	.driver = {
> +		.name = "aspire-ec",
> +		.of_match_table = aspire_ec_of_match,
> +		.pm = pm_sleep_ptr(&aspire_ec_pm_ops),
> +	},
> +	.probe = aspire_ec_probe,
> +	.id_table = aspire_ec_id,
Since it's tristate, I'd expect an entry for .remove_new here

Konrad