Re: [PATCH] power: supply: max77759_charger: fix voltage scale (mV -> uV)

[Sebastian Reichel <sebastian.reichel@collabora.com>]

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Hi,

On Thu, Apr 02, 2026 at 07:15:29AM +0000, Amit Sunil Dhamne via B4 Relay wrote:
> From: Amit Sunil Dhamne <amitsd@google.com>
> 
> CONSTANT_CHARGE_VOLTAGE_MAX property incorrectly uses mV instead of uV.
> Add fix to use uV as per the power-supply subsystem convention.
> 
> Also, add a note indicating all the properties use non negative values.
> A negative value indicates failure with the appropriate error value. In
> that case, it should not be taken as a measurement value or status.
> 
> Signed-off-by: Amit Sunil Dhamne <amitsd@google.com>
> ---
> This patch is a follow-up to the series [1]. [1] has been accepted in
> the USB subsystem tree (usb-next). However, since Sebastian has additional
> feedback [2], I am sending this patch to address it. Please note that this
> patch is based out of usb-next branch on usb tree. This patch should be
> applied on top of 70d7dd27f6dc ("power: supply: max77759: add charger driver").
> 
> [1] https://lore.kernel.org/all/20260325-max77759-charger-v9-0-4486dd297adc@google.com/
> [2] https://lore.kernel.org/all/ac2jYUA2F5oQsA2g@venus/#t
> ---

Fixes: 70d7dd27f6dc ("power: supply: max77759: add charger driver")
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Greetings,

-- Sebastian

> Output of power supply selftest:
> root@google-gs:/data/power_supply# ./test_power_supply_properties.sh
> TAP version 13
> 1..66
>  # Testing device max77759-charger
> ok 1 max77759-charger.exists
> ok 2 max77759-charger.uevent.NAME
> ok 3 max77759-charger.sysfs.type
> ok 4 max77759-charger.uevent.TYPE
> ok 5 max77759-charger.sysfs.usb_type # SKIP
>  # Reported: '1' ()
> ok 6 max77759-charger.sysfs.online
>  # Reported: '1' ()
> ok 7 max77759-charger.sysfs.present
>  # Reported: 'Charging'
> ok 8 max77759-charger.sysfs.status
> ok 9 max77759-charger.sysfs.capacity # SKIP
> ok 10 max77759-charger.sysfs.capacity_level # SKIP
> ok 11 max77759-charger.sysfs.model_name # SKIP
> ok 12 max77759-charger.sysfs.manufacturer # SKIP
> ok 13 max77759-charger.sysfs.serial_number # SKIP
> ok 14 max77759-charger.sysfs.technology # SKIP
> ok 15 max77759-charger.sysfs.cycle_count # SKIP
> ok 16 max77759-charger.sysfs.scope # SKIP
>  # Reported: '3000000' uA (3000 mA)
> ok 17 max77759-charger.sysfs.input_current_limit
> ok 18 max77759-charger.sysfs.input_voltage_limit # SKIP
> ok 19 max77759-charger.sysfs.voltage_now # SKIP
> ok 20 max77759-charger.sysfs.voltage_min # SKIP
> ok 21 max77759-charger.sysfs.voltage_max # SKIP
> ok 22 max77759-charger.sysfs.voltage_min_design # SKIP
> ok 23 max77759-charger.sysfs.voltage_max_design # SKIP
> ok 24 max77759-charger.sysfs.current_now # SKIP
> ok 25 max77759-charger.sysfs.current_max # SKIP
> ok 26 max77759-charger.sysfs.charge_now # SKIP
> ok 27 max77759-charger.sysfs.charge_full # SKIP
> ok 28 max77759-charger.sysfs.charge_full_design # SKIP
> ok 29 max77759-charger.sysfs.power_now # SKIP
> ok 30 max77759-charger.sysfs.energy_now # SKIP
> ok 31 max77759-charger.sysfs.energy_full # SKIP
> ok 32 max77759-charger.sysfs.energy_full_design # SKIP
> ok 33 max77759-charger.sysfs.energy_full_design # SKIP
>  # Testing device tcpm-source-psy-1-0025
> ok 34 tcpm-source-psy-1-0025.exists
> ok 35 tcpm-source-psy-1-0025.uevent.NAME
> ok 36 tcpm-source-psy-1-0025.sysfs.type
> ok 37 tcpm-source-psy-1-0025.uevent.TYPE
>  # Reported: 'C [PD] PD_PPS PD_SPR_AVS PD_PPS_SPR_AVS' ()
> ok 38 tcpm-source-psy-1-0025.sysfs.usb_type
>  # Reported: '1' ()
> ok 39 tcpm-source-psy-1-0025.sysfs.online
> ok 40 tcpm-source-psy-1-0025.sysfs.present # SKIP
> ok 41 tcpm-source-psy-1-0025.sysfs.status # SKIP
> ok 42 tcpm-source-psy-1-0025.sysfs.capacity # SKIP
> ok 43 tcpm-source-psy-1-0025.sysfs.capacity_level # SKIP
> ok 44 tcpm-source-psy-1-0025.sysfs.model_name # SKIP
> ok 45 tcpm-source-psy-1-0025.sysfs.manufacturer # SKIP
> ok 46 tcpm-source-psy-1-0025.sysfs.serial_number # SKIP
> ok 47 tcpm-source-psy-1-0025.sysfs.technology # SKIP
> ok 48 tcpm-source-psy-1-0025.sysfs.cycle_count # SKIP
> ok 49 tcpm-source-psy-1-0025.sysfs.scope # SKIP
> ok 50 tcpm-source-psy-1-0025.sysfs.input_current_limit # SKIP
> ok 51 tcpm-source-psy-1-0025.sysfs.input_voltage_limit # SKIP
>  # Reported: '5000000' uV (5 V)
> ok 52 tcpm-source-psy-1-0025.sysfs.voltage_now
>  # Reported: '5000000' uV (5 V)
> ok 53 tcpm-source-psy-1-0025.sysfs.voltage_min
>  # Reported: '5000000' uV (5 V)
> ok 54 tcpm-source-psy-1-0025.sysfs.voltage_max
> ok 55 tcpm-source-psy-1-0025.sysfs.voltage_min_design # SKIP
> ok 56 tcpm-source-psy-1-0025.sysfs.voltage_max_design # SKIP
>  # Reported: '3000000' uA (3000 mA)
> ok 57 tcpm-source-psy-1-0025.sysfs.current_now
>  # Reported: '3000000' uA (3000 mA)
> ok 58 tcpm-source-psy-1-0025.sysfs.current_max
> ok 59 tcpm-source-psy-1-0025.sysfs.charge_now # SKIP
> ok 60 tcpm-source-psy-1-0025.sysfs.charge_full # SKIP
> ok 61 tcpm-source-psy-1-0025.sysfs.charge_full_design # SKIP
> ok 62 tcpm-source-psy-1-0025.sysfs.power_now # SKIP
> ok 63 tcpm-source-psy-1-0025.sysfs.energy_now # SKIP
> ok 64 tcpm-source-psy-1-0025.sysfs.energy_full # SKIP
> ok 65 tcpm-source-psy-1-0025.sysfs.energy_full_design # SKIP
> ok 66 tcpm-source-psy-1-0025.sysfs.energy_full_design # SKIP
>  # 47 skipped test(s) detected.  Consider enabling relevant config options to improve coverage.
>  # Totals: pass:19 fail:0 xfail:0 xpass:0 skip:47 error:0
> ---
>  drivers/power/supply/max77759_charger.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/power/supply/max77759_charger.c b/drivers/power/supply/max77759_charger.c
> index 9bb414599f16..58594bb78426 100644
> --- a/drivers/power/supply/max77759_charger.c
> +++ b/drivers/power/supply/max77759_charger.c
> @@ -26,7 +26,7 @@
>  
>  /* Default values for Fast Charge Current & Float Voltage */
>  #define CHG_CC_DEFAULT_UA			2266770
> -#define CHG_FV_DEFAULT_MV			4300
> +#define CHG_FV_DEFAULT_UV			4300000
>  
>  #define MAX_NUM_RETRIES				3
>  #define PSY_WORK_RETRY_DELAY_MS			10
> @@ -61,10 +61,10 @@ static const struct linear_range chgcc_limit_ranges[] = {
>  	LINEAR_RANGE(200000, 0x3, 0x3C, 66670),
>  };
>  
> -/* Charge Termination Voltage Limits (in mV) */
> +/* Charge Termination Voltage Limits (in uV) */
>  static const struct linear_range chg_cv_prm_ranges[] = {
> -	LINEAR_RANGE(3800, 0x38, 0x39, 100),
> -	LINEAR_RANGE(4000, 0x0, 0x32, 10),
> +	LINEAR_RANGE(3800000, 0x38, 0x39, 100000),
> +	LINEAR_RANGE(4000000, 0x0, 0x32, 10000),
>  };
>  
>  /* USB input current limits (in uA) */
> @@ -310,14 +310,14 @@ static int get_float_voltage(struct max77759_charger *chg)
>  	return ret ? ret : val;
>  }
>  
> -static int set_float_voltage_limit(struct max77759_charger *chg, u32 fv_mv)
> +static int set_float_voltage_limit(struct max77759_charger *chg, u32 fv_uv)
>  {
>  	u32 regval;
>  	bool found;
>  
>  	linear_range_get_selector_high_array(chg_cv_prm_ranges,
>  					     ARRAY_SIZE(chg_cv_prm_ranges),
> -					     fv_mv, &regval, &found);
> +					     fv_uv, &regval, &found);
>  	if (!found)
>  		return -EINVAL;
>  
> @@ -370,6 +370,11 @@ static const enum power_supply_property max77759_charger_props[] = {
>  	POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
>  };
>  
> +/*
> + * Note: None of the properties in this driver support usage of negative values.
> + * If you do see one, it's because the function is reporting an error value and
> + * should not be taken as a measurement value or status.
> + */
>  static int max77759_charger_get_property(struct power_supply *psy,
>  					 enum power_supply_property psp,
>  					 union power_supply_propval *pval)
> @@ -557,10 +562,10 @@ static int max77759_charger_init(struct max77759_charger *chg)
>  		return ret;
>  
>  	if (power_supply_get_battery_info(chg->psy, &info)) {
> -		fv = CHG_FV_DEFAULT_MV;
> +		fv = CHG_FV_DEFAULT_UV;
>  		fast_chg_curr = CHG_CC_DEFAULT_UA;
>  	} else {
> -		fv = info->constant_charge_voltage_max_uv / 1000;
> +		fv = info->constant_charge_voltage_max_uv;
>  		fast_chg_curr = info->constant_charge_current_max_ua;
>  	}
>  
> 
> ---
> base-commit: 81ebd43cc0d6d106ce7b6ccbf7b5e40ca7f5503d
> change-id: 20260402-fix-psy-max77759-usb-next-15a4f86a08ce
> 
> Best regards,
> -- 
> Amit Sunil Dhamne <amitsd@google.com>
> 
> 

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