linux-kernel - Re: [PATCH v2] HID: logitech-hidpp: add support for Logitech G533 headset

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Date:   Fri, 05 Jun 2020 16:15:43 +0100
From:   Filipe Laíns <lains@...hlinux.org>
To:     Kamil Domański <kamil@...anski.co>,
        linux-kernel@...r.kernel.org
Cc:     Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Nestor Lopez Casado <nlopezcasad@...itech.com>
Subject: Re: [PATCH v2] HID: logitech-hidpp: add support for Logitech G533
 headset

Hi Kamil,

On v2 patches it s usual to add a changelog (could be small) to help
keep track of what changed.

On Fri, 2020-06-05 at 16:59 +0200, Kamil Domański wrote:
> Signed-off-by: Kamil Domański <kamil@...anski.co>

*snip*

> +/**
> + * hidpp20_adc_map_status_voltage() - convert HID++ code to power supply status
> + * @hidpp: HID++ device struct.
> + * @data: ADC report data.
> + * @voltage: Pointer to variable where the ADC voltage shall be written.
> + *
> + * This function decodes the ADC voltage and charge status
> + * of the device's battery.
> + *
> + * Return: Returns the power supply charge status code.
> + */
> +static int hidpp20_adc_map_status_voltage(struct hidpp_device *hidpp,
> +						u8 data[3], int *voltage)
> +{
> +	bool isConnected;
> +	bool isCharging;
> +	bool chargingComplete;
> +	bool chargingFault;

From my initial comments:

> We use snake case.

> +
> +	long flags = (long) data[2];

> Use u8 instead. Why are we even using a variable for this?

My main point here is that long means different things in different
architectures, and we only want one byte so I would go for u8.

> +
> +	*voltage = get_unaligned_be16(data);
> +	isConnected = test_bit(0, &flags);
> +	isCharging = test_bit(1, &flags);
> +	chargingComplete = test_bit(2, &flags);
> +	chargingFault = test_bit(3, &flags);

> I don't think this is needed, just do it in the ifs directly.
>
> Here I would add a #define for each bit:
>
> #define FLAG_ADC_MAP_STATUS_CONNECTED 0
> ...
> if (data[2] & FLAG_ADC_MAP_STATUS_CONNECTED)

> +
> +	if (!isConnected)
> +		return POWER_SUPPLY_STATUS_UNKNOWN;
> +
> +	if (isCharging) {
> +		if (chargingFault)
> +			return POWER_SUPPLY_STATUS_NOT_CHARGING;
> +
> +		if (chargingComplete)
> +			return POWER_SUPPLY_STATUS_FULL;
> +
> +		return POWER_SUPPLY_STATUS_CHARGING;
> +	}
> +
> +	return POWER_SUPPLY_STATUS_DISCHARGING;
> +}

The algorithm is now correct, thanks!

*snip*

> @@ -3994,6 +4190,8 @@ static const struct hid_device_id hidpp_devices[] = {
>  
>  	{ /* Logitech G403 Wireless Gaming Mouse over USB */
>  	  HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH, 0xC082) },
> +	{ /* Logitech G533 Wireless Headset over USB */
> +	  HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH, 0x0A66) },
>  	{ /* Logitech G703 Gaming Mouse over USB */
>  	  HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH, 0xC087) },
>  	{ /* Logitech G703 Hero Gaming Mouse over USB */

Same thing here. We should see if the device supports the DJ protocol
and add it in hid-logitech-dj instead.

Most of my comments here are nitpicks, I am not sure how strict
Benjamin/Jiri are about that.

Cheers,
Filipe Laíns

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