[PATCH v2 25/33] HID: logitech-hidpp: clean up G920 force-feedback helpers

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Perform several minor cleanups across the G920 force-feedback support:

- In hidpp_ff_init(), obtain the firmware version directly in a single
  expression from the USB device descriptor, drop the redundant
  hid_is_usb() check on the already-matched G920 device, and remove
  unused local variables.
- In hidpp_ff_upload_effect(), remove the dead force calculation in the
  periodic effect upload case where magnitude is written directly.
- Zero-initialize stack parameter buffers in effect upload, playback,
  autocenter, and gain helpers so unused parameter bytes sent over USB
  are always clean zeroes.
- Drop the write-only gain field from struct g920_data, remove the
  unused HIDPP_FF_GET_GLOBAL_GAINS query at probe time, and remove the
  gain cache update from the work handler.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/hid/hid-logitech-hidpp.c | 43 +++++-----------------------------------
 1 file changed, 5 insertions(+), 38 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 20f7e8367ee1..1d80e7b7a99e 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -2310,7 +2310,6 @@ static void hidpp_touchpad_raw_xy_event(struct hidpp_device *hidpp_dev,
 #define HIDPP_FF_DESTROY_EFFECT		0x41
 #define HIDPP_FF_GET_APERTURE		0x51
 #define HIDPP_FF_SET_APERTURE		0x61
-#define HIDPP_FF_GET_GLOBAL_GAINS	0x71
 #define HIDPP_FF_SET_GLOBAL_GAINS	0x81
 
 #define HIDPP_FF_EFFECT_STATE_GET	0x00
@@ -2349,7 +2348,6 @@ struct g920_data {
 	u8 feature_index;
 	u8 slot_autocenter;
 	u8 num_effects;
-	u16 gain;
 	u16 range;
 };
 
@@ -2412,8 +2410,6 @@ static void hidpp_ff_work_handler(struct work_struct *w)
 					  &response);
 	if (ret)
 		hid_err(data->hidpp->hid_dev, "Failed to send command to device!\n");
-	else if (wd->command == HIDPP_FF_SET_GLOBAL_GAINS)
-		g920->gain = (wd->params[0] << 8) + wd->params[1];
 
 	atomic_dec(&data->workqueue_size);
 	kfree(wd);
@@ -2453,7 +2449,7 @@ static int hidpp_ff_upload_effect(struct input_dev *dev, struct ff_effect *effec
 	struct hid_device *hid = hidpp->hid_dev;
 	struct g920_data *g920 = hidpp->private_data;
 	struct hidpp_report response;
-	u8 params[20];
+	u8 params[20] = {};
 	u8 size;
 	int force, error;
 
@@ -2510,7 +2506,6 @@ static int hidpp_ff_upload_effect(struct input_dev *dev, struct ff_effect *effec
 				effect->u.periodic.waveform);
 			return -EINVAL;
 		}
-		force = (effect->u.periodic.magnitude * fixp_sin16((effect->direction * 360) >> 16)) >> 15;
 		params[6] = effect->u.periodic.magnitude >> 8;
 		params[7] = effect->u.periodic.magnitude & 255;
 		params[8] = effect->u.periodic.offset >> 8;
@@ -2617,7 +2612,7 @@ static int hidpp_ff_upload_effect(struct input_dev *dev, struct ff_effect *effec
 static int hidpp_ff_playback(struct input_dev *dev, int effect_id, int value)
 {
 	struct hidpp_ff_private_data *data = dev->ff->private;
-	u8 params[2];
+	u8 params[2] = {};
 
 	params[0] = data->slots[effect_id];
 	if (!dev->ready || !params[0])
@@ -2662,22 +2657,18 @@ static void hidpp_ff_set_autocenter(struct input_dev *dev, u16 magnitude)
 {
 	struct hidpp_ff_private_data *data = dev->ff->private;
 	struct g920_data *g920 = data->hidpp->private_data;
-	u8 params[HIDPP_AUTOCENTER_PARAMS_LENGTH];
+	u8 params[HIDPP_AUTOCENTER_PARAMS_LENGTH] = {};
 
 	dbg_hid("Setting autocenter to %d.\n", magnitude);
 
 	/* start a standard spring effect */
 	params[0] = g920->slot_autocenter;
 	params[1] = HIDPP_FF_EFFECT_SPRING | HIDPP_FF_EFFECT_AUTOSTART;
-	/* zero delay and duration */
-	params[2] = params[3] = params[4] = params[5] = 0;
 	/* set coeff to 25% of saturation */
 	params[8] = params[14] = magnitude >> 11;
 	params[9] = params[15] = (magnitude >> 3) & 255;
 	params[6] = params[16] = magnitude >> 9;
 	params[7] = params[17] = (magnitude >> 1) & 255;
-	/* zero deadband and center */
-	params[10] = params[11] = params[12] = params[13] = 0;
 
 	hidpp_ff_queue_work(data, HIDPP_FF_DOWNLOAD_EFFECT, params, ARRAY_SIZE(params));
 }
@@ -2685,14 +2676,12 @@ static void hidpp_ff_set_autocenter(struct input_dev *dev, u16 magnitude)
 static void hidpp_ff_set_gain(struct input_dev *dev, u16 gain)
 {
 	struct hidpp_ff_private_data *data = dev->ff->private;
-	u8 params[4];
+	u8 params[4] = {};
 
 	dbg_hid("Setting gain to %d.\n", gain);
 
 	params[0] = gain >> 8;
 	params[1] = gain & 255;
-	params[2] = 0; /* no boost */
-	params[3] = 0;
 
 	hidpp_ff_queue_work(data, HIDPP_FF_SET_GLOBAL_GAINS, params, ARRAY_SIZE(params));
 }
@@ -2826,17 +2815,10 @@ static int hidpp_ff_init(struct hidpp_device *hidpp, struct input_dev *dev)
 {
 	struct hid_device *hid = hidpp->hid_dev;
 	struct g920_data *g920 = hidpp->private_data;
-	struct usb_device_descriptor *udesc;
-	u16 bcdDevice;
 	struct ff_device *ff;
 	int error, j, num_slots = g920->num_effects;
 	u8 version;
 
-	if (!hid_is_usb(hid)) {
-		hid_err(hid, "device is not USB\n");
-		return -ENODEV;
-	}
-
 	struct hidpp_ff_private_data *data __free(kfree) =
 		kzalloc_flex(*data, slots, num_slots);
 	if (!data)
@@ -2853,9 +2835,7 @@ static int hidpp_ff_init(struct hidpp_device *hidpp, struct input_dev *dev)
 		return -ENOMEM;
 
 	/* Get firmware release */
-	udesc = &(hid_to_usb_dev(hid)->descriptor);
-	bcdDevice = le16_to_cpu(udesc->bcdDevice);
-	version = bcdDevice & 255;
+	version = le16_to_cpu(hid_to_usb_dev(hid)->descriptor.bcdDevice) & 0xff;
 
 	/* Set supported force feedback capabilities */
 	for (j = 0; hidpp_ff_effects[j] >= 0; j++)
@@ -3462,19 +3442,6 @@ static int g920_get_config(struct hidpp_device *hidpp)
 	data.range = ret ?
 		900 : get_unaligned_be16(&response.fap.params[0]);
 
-	/* Read the current gain values */
-	ret = hidpp_send_fap_command_sync(hidpp, data.feature_index,
-					  HIDPP_FF_GET_GLOBAL_GAINS,
-					  NULL, 0,
-					  &response);
-	if (ret)
-		hid_warn(hidpp->hid_dev,
-			 "Failed to read gain values from device!\n");
-	data.gain = ret ?
-		0xffff : get_unaligned_be16(&response.fap.params[0]);
-
-	/* ignore boost value at response.fap.params[2] */
-
 	ret = g920_ff_set_autocenter(hidpp, &data);
 	if (ret)
 		return ret;

-- 
2.56.0.542.g3ef89b7020-goog