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Message-ID: <jil4fvsfddgdj46yjy5rzw7zg6xlb2u2pgzlpkn2bte6du2ht6@5plrpdaf4u7w>
Date: Thu, 13 Nov 2025 11:54:04 +0100
From: Benjamin Tissoires <bentiss@...nel.org>
To: Lucas Zampieri <lzampier@...hat.com>
Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
Jiri Kosina <jikos@...nel.org>, Sebastian Reichel <sre@...nel.org>,
Bastien Nocera <hadess@...ess.net>, linux-pm@...r.kernel.org
Subject: Re: [RFC PATCH v2 2/3] HID: input: Refactor battery code to use
struct hid_battery
On Nov 13 2025, Lucas Zampieri wrote:
> Refactor the battery handling code to use the newly introduced
> struct hid_battery internally, replacing direct access to individual
> power_supply and state fields.
>
> The legacy dev->battery and dev->battery_* fields are maintained and
> synchronized for backward compatibility. This refactoring prepares
> the code for supporting multiple batteries per device in a subsequent
> patch.
>
> Signed-off-by: Lucas Zampieri <lzampier@...hat.com>
> ---
> drivers/hid/hid-input.c | 125 ++++++++++++++++++++++++++--------------
> 1 file changed, 83 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index e56e7de53279..0e71efea9da3 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -454,7 +454,8 @@ static int hidinput_get_battery_property(struct power_supply *psy,
> enum power_supply_property prop,
> union power_supply_propval *val)
> {
> - struct hid_device *dev = power_supply_get_drvdata(psy);
> + struct hid_battery *bat = power_supply_get_drvdata(psy);
> + struct hid_device *dev = bat->dev;
> int value;
> int ret = 0;
>
> @@ -465,13 +466,13 @@ static int hidinput_get_battery_property(struct power_supply *psy,
> break;
>
> case POWER_SUPPLY_PROP_CAPACITY:
> - if (dev->battery_status != HID_BATTERY_REPORTED &&
> - !dev->battery_avoid_query) {
> + if (bat->status != HID_BATTERY_REPORTED &&
> + !bat->avoid_query) {
> value = hidinput_query_battery_capacity(dev);
> if (value < 0)
> return value;
> } else {
> - value = dev->battery_capacity;
> + value = bat->capacity;
> }
>
> val->intval = value;
> @@ -482,20 +483,20 @@ static int hidinput_get_battery_property(struct power_supply *psy,
> break;
>
> case POWER_SUPPLY_PROP_STATUS:
> - if (dev->battery_status != HID_BATTERY_REPORTED &&
> - !dev->battery_avoid_query) {
> + if (bat->status != HID_BATTERY_REPORTED &&
> + !bat->avoid_query) {
> value = hidinput_query_battery_capacity(dev);
> if (value < 0)
> return value;
>
> - dev->battery_capacity = value;
> - dev->battery_status = HID_BATTERY_QUERIED;
> + bat->capacity = value;
> + bat->status = HID_BATTERY_QUERIED;
> }
>
> - if (dev->battery_status == HID_BATTERY_UNKNOWN)
> + if (bat->status == HID_BATTERY_UNKNOWN)
> val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
> else
> - val->intval = dev->battery_charge_status;
> + val->intval = bat->charge_status;
> break;
>
> case POWER_SUPPLY_PROP_SCOPE:
> @@ -513,8 +514,9 @@ static int hidinput_get_battery_property(struct power_supply *psy,
> static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
> struct hid_field *field, bool is_percentage)
> {
> + struct hid_battery *bat;
> struct power_supply_desc *psy_desc;
> - struct power_supply_config psy_cfg = { .drv_data = dev, };
> + struct power_supply_config psy_cfg;
> unsigned quirks;
> s32 min, max;
> int error;
> @@ -530,16 +532,22 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
> if (quirks & HID_BATTERY_QUIRK_IGNORE)
> return 0;
>
> - psy_desc = kzalloc(sizeof(*psy_desc), GFP_KERNEL);
> - if (!psy_desc)
> + bat = kzalloc(sizeof(*bat), GFP_KERNEL);
> + if (!bat)
> return -ENOMEM;
>
> + psy_desc = kzalloc(sizeof(*psy_desc), GFP_KERNEL);
> + if (!psy_desc) {
> + error = -ENOMEM;
> + goto err_free_bat;
> + }
> +
> psy_desc->name = kasprintf(GFP_KERNEL, "hid-%s-battery",
> strlen(dev->uniq) ?
> dev->uniq : dev_name(&dev->dev));
> if (!psy_desc->name) {
> error = -ENOMEM;
> - goto err_free_mem;
> + goto err_free_desc;
I wonder if a devm conversion of the whole battery support handling
would not be beneficial here.
> }
>
> psy_desc->type = POWER_SUPPLY_TYPE_BATTERY;
> @@ -559,63 +567,85 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
> if (quirks & HID_BATTERY_QUIRK_FEATURE)
> report_type = HID_FEATURE_REPORT;
>
> - dev->battery_min = min;
> - dev->battery_max = max;
> - dev->battery_report_type = report_type;
> - dev->battery_report_id = field->report->id;
> - dev->battery_charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
> + /* Initialize battery structure */
> + bat->dev = dev;
> + bat->min = min;
> + bat->max = max;
> + bat->report_type = report_type;
> + bat->report_id = field->report->id;
> + bat->charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
> + bat->status = HID_BATTERY_UNKNOWN;
>
> /*
> * Stylus is normally not connected to the device and thus we
> * can't query the device and get meaningful battery strength.
> * We have to wait for the device to report it on its own.
> */
> - dev->battery_avoid_query = report_type == HID_INPUT_REPORT &&
> - field->physical == HID_DG_STYLUS;
> + bat->avoid_query = report_type == HID_INPUT_REPORT &&
> + field->physical == HID_DG_STYLUS;
>
> if (quirks & HID_BATTERY_QUIRK_AVOID_QUERY)
> - dev->battery_avoid_query = true;
> + bat->avoid_query = true;
>
> - dev->battery = power_supply_register(&dev->dev, psy_desc, &psy_cfg);
> - if (IS_ERR(dev->battery)) {
> - error = PTR_ERR(dev->battery);
> + psy_cfg.drv_data = bat;
> + bat->ps = power_supply_register(&dev->dev, psy_desc, &psy_cfg);
> + if (IS_ERR(bat->ps)) {
> + error = PTR_ERR(bat->ps);
> hid_warn(dev, "can't register power supply: %d\n", error);
> goto err_free_name;
> }
>
> - power_supply_powers(dev->battery, &dev->dev);
> + power_supply_powers(bat->ps, &dev->dev);
> +
> + /* Maintain legacy single battery fields for backward compatibility */
> + dev->battery = bat->ps;
> + dev->battery_min = bat->min;
> + dev->battery_max = bat->max;
> + dev->battery_report_type = bat->report_type;
> + dev->battery_report_id = bat->report_id;
> + dev->battery_charge_status = bat->charge_status;
> + dev->battery_status = bat->status;
> + dev->battery_avoid_query = bat->avoid_query;
Already mentioned in the cover letter, but what's the point of keeping
those legacy fields when the exact same data is stored in bat?
> +
> return 0;
>
> err_free_name:
> kfree(psy_desc->name);
> -err_free_mem:
> +err_free_desc:
> kfree(psy_desc);
> - dev->battery = NULL;
> +err_free_bat:
> + kfree(bat);
> return error;
> }
>
> static void hidinput_cleanup_battery(struct hid_device *dev)
> {
> + struct hid_battery *bat;
> const struct power_supply_desc *psy_desc;
>
> if (!dev->battery)
> return;
>
> + bat = power_supply_get_drvdata(dev->battery);
> psy_desc = dev->battery->desc;
> power_supply_unregister(dev->battery);
> kfree(psy_desc->name);
> kfree(psy_desc);
> + kfree(bat);
> dev->battery = NULL;
> }
>
> -static bool hidinput_update_battery_charge_status(struct hid_device *dev,
> +static bool hidinput_update_battery_charge_status(struct hid_battery *bat,
> unsigned int usage, int value)
> {
> switch (usage) {
> case HID_BAT_CHARGING:
> - dev->battery_charge_status = value ?
> - POWER_SUPPLY_STATUS_CHARGING :
> - POWER_SUPPLY_STATUS_DISCHARGING;
> + bat->charge_status = value ?
> + POWER_SUPPLY_STATUS_CHARGING :
> + POWER_SUPPLY_STATUS_DISCHARGING;
> + /* Update legacy field for backward compatibility */
> + if (bat->dev->battery == bat->ps)
> + bat->dev->battery_charge_status = bat->charge_status;
> return true;
> }
>
> @@ -625,32 +655,43 @@ static bool hidinput_update_battery_charge_status(struct hid_device *dev,
> static void hidinput_update_battery(struct hid_device *dev, unsigned int usage,
> int value)
> {
> + struct hid_battery *bat;
> int capacity;
>
> if (!dev->battery)
> return;
>
> - if (hidinput_update_battery_charge_status(dev, usage, value)) {
> - power_supply_changed(dev->battery);
> + bat = power_supply_get_drvdata(dev->battery);
> +
> + if (hidinput_update_battery_charge_status(bat, usage, value)) {
> + power_supply_changed(bat->ps);
> return;
> }
>
> if ((usage & HID_USAGE_PAGE) == HID_UP_DIGITIZER && value == 0)
> return;
>
> - if (value < dev->battery_min || value > dev->battery_max)
> + if (value < bat->min || value > bat->max)
> return;
>
> capacity = hidinput_scale_battery_capacity(dev, value);
>
> - if (dev->battery_status != HID_BATTERY_REPORTED ||
> - capacity != dev->battery_capacity ||
> - ktime_after(ktime_get_coarse(), dev->battery_ratelimit_time)) {
> - dev->battery_capacity = capacity;
> - dev->battery_status = HID_BATTERY_REPORTED;
> - dev->battery_ratelimit_time =
> + if (bat->status != HID_BATTERY_REPORTED ||
> + capacity != bat->capacity ||
> + ktime_after(ktime_get_coarse(), bat->ratelimit_time)) {
> + bat->capacity = capacity;
> + bat->status = HID_BATTERY_REPORTED;
> + bat->ratelimit_time =
> ktime_add_ms(ktime_get_coarse(), 30 * 1000);
> - power_supply_changed(dev->battery);
> +
> + /* Update legacy fields for backward compatibility */
> + if (dev->battery == bat->ps) {
> + dev->battery_capacity = bat->capacity;
> + dev->battery_status = bat->status;
> + dev->battery_ratelimit_time = bat->ratelimit_time;
> + }
> +
> + power_supply_changed(bat->ps);
> }
> }
> #else /* !CONFIG_HID_BATTERY_STRENGTH */
> --
> 2.51.1
>
Cheers,
Benjamin
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