Re: [PATCH] HID: logitech-hidpp: battery: provide CAPACITY property for newer devices

[Bastien Nocera]

Hey Hamza,

On Fri, 2021-07-23 at 02:23 -0400, Hamza Mahfooz wrote:
> For devices that only support the BATTERY_VOLTAGE (0x1001) feature,
> UPower
> requires the additional information provided by this patch, to set
> them up.
> 
> Signed-off-by: Hamza Mahfooz <someguy@xxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/hid/hid-logitech-hidpp.c | 31
> ++++++++++++++++++++++++++++++-
>  1 file changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-
> logitech-hidpp.c
> index 61635e629469..662c335e9c17 100644
> --- a/drivers/hid/hid-logitech-hidpp.c
> +++ b/drivers/hid/hid-logitech-hidpp.c
> @@ -1331,6 +1331,32 @@ static int
> hidpp20_battery_get_battery_voltage(struct hidpp_device *hidpp,
>         return 0;
>  }
>  
> +static int hidpp20_map_battery_capacity(int voltage)
> +{
> +       static const int voltages[] = {
> +               4186, 4156, 4143, 4133, 4122, 4113, 4103, 4094, 4086,
> 4075,
> +               4067, 4059, 4051, 4043, 4035, 4027, 4019, 4011, 4003,
> 3997,
> +               3989, 3983, 3976, 3969, 3961, 3955, 3949, 3942, 3935,
> 3929,
> +               3922, 3916, 3909, 3902, 3896, 3890, 3883, 3877, 3870,
> 3865,
> +               3859, 3853, 3848, 3842, 3837, 3833, 3828, 3824, 3819,
> 3815,
> +               3811, 3808, 3804, 3800, 3797, 3793, 3790, 3787, 3784,
> 3781,
> +               3778, 3775, 3772, 3770, 3767, 3764, 3762, 3759, 3757,
> 3754,
> +               3751, 3748, 3744, 3741, 3737, 3734, 3730, 3726, 3724,
> 3720,
> +               3717, 3714, 3710, 3706, 3702, 3697, 3693, 3688, 3683,
> 3677,
> +               3671, 3666, 3662, 3658, 3654, 3646, 3633, 3612, 3579,
> 3537,
> +               3500
> +       };
> +
> +       int i;
> +
> +       for (i = 0; i < (sizeof(voltages) / sizeof(int)); i++) {

Use ARRAY_SIZE()

> +               if (voltage >= voltages[i])
> +                       return 100 - i;

I don't really like this part, which seems to rely on things which
aren't asserted. Is there a way to make sure that voltages[] is 100
items and they're all initialised?

If you tested this, could you also mention which devices you tested
this on in the commit message?

Thanks for picking this up!

> +       }
> +
> +       return 0;
> +}
> +
>  static int hidpp20_query_battery_voltage_info(struct hidpp_device
> *hidpp)
>  {
>         u8 feature_type;
> @@ -1354,6 +1380,7 @@ static int
> hidpp20_query_battery_voltage_info(struct hidpp_device *hidpp)
>  
>         hidpp->battery.status = status;
>         hidpp->battery.voltage = voltage;
> +       hidpp->battery.capacity =
> hidpp20_map_battery_capacity(voltage);
>         hidpp->battery.level = level;
>         hidpp->battery.charge_type = charge_type;
>         hidpp->battery.online = status !=
> POWER_SUPPLY_STATUS_NOT_CHARGING;
> @@ -1378,6 +1405,7 @@ static int hidpp20_battery_voltage_event(struct
> hidpp_device *hidpp,
>  
>         if (voltage != hidpp->battery.voltage || status != hidpp-
> >battery.status) {
>                 hidpp->battery.voltage = voltage;
> +               hidpp->battery.capacity =
> hidpp20_map_battery_capacity(voltage);
>                 hidpp->battery.status = status;
>                 hidpp->battery.level = level;
>                 hidpp->battery.charge_type = charge_type;
> @@ -3717,7 +3745,8 @@ static int hidpp_initialize_battery(struct
> hidpp_device *hidpp)
>         num_battery_props = ARRAY_SIZE(hidpp_battery_props) - 3;
>  
>         if (hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_MILEAGE ||
> -           hidpp->capabilities &
> HIDPP_CAPABILITY_BATTERY_PERCENTAGE)
> +           hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_PERCENTAGE
> ||
> +           hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_VOLTAGE)
>                 battery_props[num_battery_props++] =
>                                 POWER_SUPPLY_PROP_CAPACITY;
>