Re: [PATCH v2 05/13] HID: playstation: add DualSense accelerometer and gyroscope support.

["Barnabás Pőcze" <pobrn@protonmail.com>]

Hi


2021. január 2., szombat 23:31 keltezéssel, Roderick Colenbrander írta:

> From: Roderick Colenbrander <roderick.colenbrander@sony.com>
>
> The DualSense features an accelerometer and gyroscope. The data is
> embedded into the main HID input reports. Expose both sensors through
> through a separate evdev node.
>
> Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com>
> [...]
> +static struct input_dev *ps_sensors_create(struct hid_device *hdev, int accel_range, int accel_res,
> +		int gyro_range, int gyro_res)
> +{
> +	struct input_dev *sensors;
> +	int ret;
> +
> +	sensors = ps_allocate_input_dev(hdev, "Motion Sensors");
> +	if (IS_ERR(sensors))
> +		return ERR_PTR(-ENOMEM);

I know that at the moment ENOMEM is the only possible error, but I believe
`return ERR_CAST(sensors);` would be better. (Or even just `return sensors;`.)


> +
> +	__set_bit(INPUT_PROP_ACCELEROMETER, sensors->propbit);
> +
> +	/* Accelerometer */
> +	input_set_abs_params(sensors, ABS_X, -accel_range, accel_range, 16, 0);
> +	input_set_abs_params(sensors, ABS_Y, -accel_range, accel_range, 16, 0);
> +	input_set_abs_params(sensors, ABS_Z, -accel_range, accel_range, 16, 0);
> +	input_abs_set_res(sensors, ABS_X, accel_res);
> +	input_abs_set_res(sensors, ABS_Y, accel_res);
> +	input_abs_set_res(sensors, ABS_Z, accel_res);
> +
> +	/* Gyroscope */
> +	input_set_abs_params(sensors, ABS_RX, -gyro_range, gyro_range, 16, 0);
> +	input_set_abs_params(sensors, ABS_RY, -gyro_range, gyro_range, 16, 0);
> +	input_set_abs_params(sensors, ABS_RZ, -gyro_range, gyro_range, 16, 0);
> +	input_abs_set_res(sensors, ABS_RX, gyro_res);
> +	input_abs_set_res(sensors, ABS_RY, gyro_res);
> +	input_abs_set_res(sensors, ABS_RZ, gyro_res);
> +
> +	ret = input_register_device(sensors);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	return sensors;
> +}
> [...]
> +static int dualsense_get_calibration_data(struct dualsense *ds)
> +{
> +	short gyro_pitch_bias, gyro_pitch_plus, gyro_pitch_minus;
> +	short gyro_yaw_bias, gyro_yaw_plus, gyro_yaw_minus;
> +	short gyro_roll_bias, gyro_roll_plus, gyro_roll_minus;
> +	short gyro_speed_plus, gyro_speed_minus;
> +	short acc_x_plus, acc_x_minus;
> +	short acc_y_plus, acc_y_minus;
> +	short acc_z_plus, acc_z_minus;
> +	int speed_2x;
> +	int range_2g;
> +	int ret = 0;
> +	uint8_t *buf;
> +
> +	buf = kzalloc(DS_FEATURE_REPORT_CALIBRATION_SIZE, GFP_KERNEL);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	ret = hid_hw_raw_request(ds->base.hdev, DS_FEATURE_REPORT_CALIBRATION, buf,
> +			DS_FEATURE_REPORT_CALIBRATION_SIZE, HID_FEATURE_REPORT, HID_REQ_GET_REPORT);

I think it would be better if lines were aligned. I have missed this in other patches,
so if you decide to make this change, please do it everywhere.


> +	if (ret < 0)
> +		goto err_free;
> +	else if (ret != DS_FEATURE_REPORT_CALIBRATION_SIZE) {

As per coding style[1], please either use {} for all branches, or just drop the
`else` and maybe add a new line:

```
if (ret < 0)
  goto ...

if (ret != ...) {
  ...
}
```


> +		hid_err(ds->base.hdev, "failed to retrieve DualSense calibration info\n");

I think this message could be improved to better pinpoint the exact problem
that triggered it.


> +		ret = -EINVAL;
> +		goto err_free;
> +	}
> +
> +	gyro_pitch_bias  = get_unaligned_le16(&buf[1]);
> +	gyro_yaw_bias    = get_unaligned_le16(&buf[3]);
> +	gyro_roll_bias   = get_unaligned_le16(&buf[5]);
> +	gyro_pitch_plus  = get_unaligned_le16(&buf[7]);
> +	gyro_pitch_minus = get_unaligned_le16(&buf[9]);
> +	gyro_yaw_plus    = get_unaligned_le16(&buf[11]);
> +	gyro_yaw_minus   = get_unaligned_le16(&buf[13]);
> +	gyro_roll_plus   = get_unaligned_le16(&buf[15]);
> +	gyro_roll_minus  = get_unaligned_le16(&buf[17]);
> +	gyro_speed_plus  = get_unaligned_le16(&buf[19]);
> +	gyro_speed_minus = get_unaligned_le16(&buf[21]);
> +	acc_x_plus       = get_unaligned_le16(&buf[23]);
> +	acc_x_minus      = get_unaligned_le16(&buf[25]);
> +	acc_y_plus       = get_unaligned_le16(&buf[27]);
> +	acc_y_minus      = get_unaligned_le16(&buf[29]);
> +	acc_z_plus       = get_unaligned_le16(&buf[31]);
> +	acc_z_minus      = get_unaligned_le16(&buf[33]);
> +
> +	/* Set gyroscope calibration and normalization parameters.
> +	 * Data values will be normalized to 1/DS_GYRO_RES_PER_DEG_S degree/s.
> +	 */

A small note, as written in [2], the preferred style of multi-line comments is different,
so you might want to change the comments. If you decide to make this change, please
do it everywhere.


> +	speed_2x = (gyro_speed_plus + gyro_speed_minus);
> +	ds->gyro_calib_data[0].abs_code = ABS_RX;
> +	ds->gyro_calib_data[0].bias = gyro_pitch_bias;
> +	ds->gyro_calib_data[0].sens_numer = speed_2x*DS_GYRO_RES_PER_DEG_S;
> +	ds->gyro_calib_data[0].sens_denom = gyro_pitch_plus - gyro_pitch_minus;
> +
> +	ds->gyro_calib_data[1].abs_code = ABS_RY;
> +	ds->gyro_calib_data[1].bias = gyro_yaw_bias;
> +	ds->gyro_calib_data[1].sens_numer = speed_2x*DS_GYRO_RES_PER_DEG_S;
> +	ds->gyro_calib_data[1].sens_denom = gyro_yaw_plus - gyro_yaw_minus;
> +
> +	ds->gyro_calib_data[2].abs_code = ABS_RZ;
> +	ds->gyro_calib_data[2].bias = gyro_roll_bias;
> +	ds->gyro_calib_data[2].sens_numer = speed_2x*DS_GYRO_RES_PER_DEG_S;
> +	ds->gyro_calib_data[2].sens_denom = gyro_roll_plus - gyro_roll_minus;
> +
> +	/* Set accelerometer calibration and normalization parameters.
> +	 * Data values will be normalized to 1/DS_ACC_RES_PER_G G.
                                                                ^
Minor thing, but I believe it should be 'g', not 'G'?


> +	 */
> +	range_2g = acc_x_plus - acc_x_minus;
> +	ds->accel_calib_data[0].abs_code = ABS_X;
> +	ds->accel_calib_data[0].bias = acc_x_plus - range_2g / 2;
> +	ds->accel_calib_data[0].sens_numer = 2*DS_ACC_RES_PER_G;
> +	ds->accel_calib_data[0].sens_denom = range_2g;
> +
> +	range_2g = acc_y_plus - acc_y_minus;
> +	ds->accel_calib_data[1].abs_code = ABS_Y;
> +	ds->accel_calib_data[1].bias = acc_y_plus - range_2g / 2;
> +	ds->accel_calib_data[1].sens_numer = 2*DS_ACC_RES_PER_G;
> +	ds->accel_calib_data[1].sens_denom = range_2g;
> +
> +	range_2g = acc_z_plus - acc_z_minus;
> +	ds->accel_calib_data[2].abs_code = ABS_Z;
> +	ds->accel_calib_data[2].bias = acc_z_plus - range_2g / 2;
> +	ds->accel_calib_data[2].sens_numer = 2*DS_ACC_RES_PER_G;
> +	ds->accel_calib_data[2].sens_denom = range_2g;
> +
> +err_free:
> +	kfree(buf);
> +	return ret;
> +}
> +
>  static int dualsense_get_mac_address(struct dualsense *ds)
>  {
>  	uint8_t *buf;
> @@ -319,6 +469,7 @@  static int dualsense_parse_report(struct ps_device *ps_dev, struct hid_report *r
>  	struct dualsense_input_report *ds_report;
>  	uint8_t battery_data, battery_capacity, charging_status, value;
>  	int battery_status;
> +	uint16_t sensor_timestamp;
>  	unsigned long flags;
>  	int i;
>
> @@ -361,6 +512,44 @@  static int dualsense_parse_report(struct ps_device *ps_dev, struct hid_report *r
>  	input_report_key(ds->gamepad, BTN_MODE,   ds_report->buttons[2] & DS_BUTTONS2_PS_HOME);
>  	input_sync(ds->gamepad);
>
> +	/* Parse and calibrate gyroscope data. */
> +	for (i = 0; i < 3; i++) {

I think `i < ARRAY_SIZE(...)` would be better.
And I would add a `static_assert(ARRAY_SIZE(ds_report->gyro) == ARRAY_SIZE(ds->gyro_calib_data))`
somewhere around here just to be safe. Or define a new constant like `DS_GYRO_DIMS`
and use that to define the arrays. Or both. *


> +		int raw_data = (short)le16_to_cpu(ds_report->gyro[i]);
> +		int calib_data = mult_frac(ds->gyro_calib_data[i].sens_numer,
> +				raw_data - ds->gyro_calib_data[i].bias,
> +				ds->gyro_calib_data[i].sens_denom);

I believe it would be better if the second and third lines was aligned. **


> +
> +		input_report_abs(ds->sensors, ds->gyro_calib_data[i].abs_code, calib_data);
> +	}
> +
> +	/* Parse and calibrate accelerometer data. */
> +	for (i = 0; i < 3; i++) {

Same here. *


> +		int raw_data = (short)le16_to_cpu(ds_report->accel[i]);
> +		int calib_data = mult_frac(ds->accel_calib_data[i].sens_numer,
> +				raw_data - ds->accel_calib_data[i].bias,
> +				ds->accel_calib_data[i].sens_denom);

Same here. **


> +
> +		input_report_abs(ds->sensors, ds->accel_calib_data[i].abs_code, calib_data);
> +	}
> +
> +	/* Convert timestamp (in 0.33us unit) to timestamp_us */
> +	sensor_timestamp = le32_to_cpu(ds_report->sensor_timestamp);
> +	if (!ds->sensor_timestamp_initialized) {
> +		ds->sensor_timestamp_us = sensor_timestamp / 3;
> +		ds->sensor_timestamp_initialized = true;
> +	} else {
> +		uint32_t delta;
> +
> +		if (ds->prev_sensor_timestamp > sensor_timestamp)
> +			delta = (U32_MAX - ds->prev_sensor_timestamp + sensor_timestamp + 1);
> +		else
> +			delta = sensor_timestamp - ds->prev_sensor_timestamp;
> +		ds->sensor_timestamp_us += delta / 3;
> +	}
> +	ds->prev_sensor_timestamp = sensor_timestamp;
> +	input_event(ds->sensors, EV_MSC, MSC_TIMESTAMP, ds->sensor_timestamp_us);
> +	input_sync(ds->sensors);
> +
>  	for (i = 0; i < 2; i++) {
>  		bool active = (ds_report->points[i].contact & DS_TOUCH_POINT_INACTIVE) ? false : true;
>
> @@ -446,12 +635,25 @@  static struct ps_device *dualsense_create(struct hid_device *hdev)
>  	}
>  	snprintf(hdev->uniq, sizeof(hdev->uniq), "%pMR", ds->base.mac_address);
>
> +	ret = dualsense_get_calibration_data(ds);
> +	if (ret < 0) {
> +		hid_err(hdev, "Failed to get calibration data from DualSense\n");
> +		goto err;
> +	}
> +
>  	ds->gamepad = ps_gamepad_create(hdev);
>  	if (IS_ERR(ds->gamepad)) {
>  		ret = PTR_ERR(ds->gamepad);
>  		goto err;
>  	}
>
> +	ds->sensors = ps_sensors_create(hdev, DS_ACC_RANGE, DS_ACC_RES_PER_G,
> +			DS_GYRO_RANGE, DS_GYRO_RES_PER_DEG_S);

I believe it would be better if the second line was aligned to the `h` in 'hdev'.


> +	if (IS_ERR(ds->sensors)) {
> +		ret = PTR_ERR(ds->sensors);
> +		goto err;
> +	}
> +
>  	ds->touchpad = ps_touchpad_create(hdev, DS_TOUCHPAD_WIDTH, DS_TOUCHPAD_HEIGHT, 2);
>  	if (IS_ERR(ds->touchpad)) {
>  		ret = PTR_ERR(ds->touchpad);
>


[1]: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
[2]: https://www.kernel.org/doc/html/latest/process/coding-style.html#commenting


Regards,
Barnabás Pőcze