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hid-xpadneo: Use work queue for rumble effects
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This makes the rumble playback asynchronous from the playback callback.

This reworks much of the code-design and replaces the previous patch
for sending rumble reports only when there's a rumble command to do.
With this change, we now get the following kernel message immediately
on disconnects:

    xpadneo 0005:045E:02FD.0054: failed to send FF report

The general design is a valuable effort on improving code quality, as
it simplifies some complex functions.

Maybe-related: atar-axis#171
Maybe-related: atar-axis#122
Maybe-affects: atar-axis#180
Signed-off-by: Kai Krakow <[email protected]>
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@kakra
kakra committed May 5, 2020
1 parent 4865e46 commit 91cf71c
Showing 1 changed file with 83 additions and 80 deletions.
163 changes: 83 additions & 80 deletions hid-xpadneo/src/hid-xpadneo.c
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Original file line number Diff line number Diff line change
Expand Up @@ -121,16 +121,18 @@ enum {
};

struct ff_data {
u8 enable_actuators;
u8 enable;
u8 magnitude_left_trigger;
u8 magnitude_right_trigger;
u8 magnitude_left;
u8 magnitude_right;
u8 duration;
u8 start_delay;
u8 pulse_sustain_10ms;
u8 pulse_release_10ms;
u8 loop_count;
} __packed;

#define XPADNEO_ONES_FF_REPORT 3

struct ff_report {
u8 report_id;
struct ff_data ff;
Expand Down Expand Up @@ -186,31 +188,53 @@ struct xpadneo_devdata {
/* axis states */
s32 last_abs_z;
s32 last_abs_rz;

/* buffer for ff_worker */
struct work_struct ff_worker;
struct ff_data ff;
void *output_report_dmabuf;
};


void create_ff_pck (struct ff_report *pck, u8 id, u8 en_act,
u8 mag_lt, u8 mag_rt, u8 mag_l, u8 mag_r,
u8 start_delay) {
/*
* Force Feedback Worker
*
* This function is called by the kernel worker thread.
*/
static void xpadneo_ff_worker(struct work_struct *work)
{
struct xpadneo_devdata *xdata = container_of(work, struct xpadneo_devdata, ff_worker);
struct hid_device *hdev = xdata->hdev;
struct ff_report *r = xdata->output_report_dmabuf;
int ret;

pck->report_id = id;
memset(r, 0, sizeof(*r));

pck->ff.enable_actuators = en_act;
pck->ff.magnitude_left_trigger = mag_lt;
pck->ff.magnitude_right_trigger = mag_rt;
pck->ff.magnitude_left = mag_l;
pck->ff.magnitude_right = mag_r;
pck->ff.duration = 0xFF;
pck->ff.start_delay = start_delay;
pck->ff.loop_count = 0xFF;
r->report_id = XPADNEO_ONES_FF_REPORT;

/* It is up to the Input-Subsystem to start and stop effects as needed.
* All WE need to do is to play the effect at least 32767 ms long.
* Take a look here:
* https://stackoverflow.com/questions/48034091/
* We therefore simply play the effect as long as possible, which is
* 2, 55s * 255 = 650, 25s ~ = 10min
*/
/* the user can disable some rumble motors */
r->ff.enable = FF_ENABLE_ALL;
if (param_disable_ff & PARAM_DISABLE_FF_TRIGGER)
r->ff.enable &= ~(FF_ENABLE_LEFT_TRIGGER | FF_ENABLE_RIGHT_TRIGGER);
if (param_disable_ff & PARAM_DISABLE_FF_MAIN)
r->ff.enable &= ~(FF_ENABLE_LEFT | FF_ENABLE_RIGHT);

/* ff-memless has a time resolution of 50ms but we pulse the motors
* as long as possible */
r->ff.pulse_sustain_10ms = U8_MAX;
r->ff.loop_count = U8_MAX;

/* trigger motors */
r->ff.magnitude_left_trigger = xdata->ff.magnitude_left_trigger;
r->ff.magnitude_right_trigger = xdata->ff.magnitude_right_trigger;

/* main motors */
r->ff.magnitude_left = xdata->ff.magnitude_left;
r->ff.magnitude_right = xdata->ff.magnitude_right;

ret = hid_hw_output_report(hdev, (__u8 *)r, sizeof(*r));
if (ret < 0)
hid_warn(hdev, "failed to send FF report: %d\n", ret);
}


Expand All @@ -228,17 +252,9 @@ void create_ff_pck (struct ff_report *pck, u8 id, u8 en_act,
static int xpadneo_ff_play(struct input_dev *dev, void *data,
struct ff_effect *effect)
{
struct ff_report ff_pck;
u32 weak, strong, direction, max, max_damped, max_unscaled;
u8 mag_main_right, mag_main_left, mag_trigger_right, mag_trigger_left;
u8 ff_active;

const int fractions_percent[]
= {100, 96, 85, 69, 50, 31, 15, 4, 0, 4, 15, 31, 50, 69, 85, 96, 100};
const int proportions_idx_max = 16;
u8 index_left, index_right;
int fraction_TL, fraction_TR;
u8 trigger_rumble_damping_nonzero;

enum {
DIRECTION_DOWN = 0x0000,
Expand All @@ -247,11 +263,11 @@ static int xpadneo_ff_play(struct input_dev *dev, void *data,
DIRECTION_RIGHT = 0xC000,
};

int fraction_TL, fraction_TR;
u32 weak, strong, direction, max_damped, max_unscaled;

struct hid_device *hdev = input_get_drvdata(dev);

if (param_disable_ff == PARAM_DISABLE_FF_ALL)
return 0;
struct xpadneo_devdata *xdata = hid_get_drvdata(hdev);

if (effect->type != FF_RUMBLE)
return 0;
Expand All @@ -264,59 +280,42 @@ static int xpadneo_ff_play(struct input_dev *dev, void *data,
hid_dbg_lvl(DBG_LVL_FEW, hdev, "playing effect: strong: %#04x, weak: %#04x, direction: %#04x\n",
strong, weak, direction);

/* calculate the physical magnitudes */
mag_main_right = (u8)((weak * 100) / 0xFFFF); /* scale from 16 bit to 0..100 */
mag_main_left = (u8)((strong * 100) / 0xFFFF); /* scale from 16 bit to 0..100 */
/* calculate the physical magnitudes, scale from 16 bit to 0..100 */
xdata->ff.magnitude_left = (u8)((strong * 100) / U16_MAX);
xdata->ff.magnitude_right = (u8)((weak * 100) / U16_MAX);

/* we want to keep the rumbling at the triggers below the maximum
* of the weak and strong main rumble
*/
max_unscaled = weak > strong ? weak : strong;

/* get the proportions from a precalculated cosine table
* calculation goes like:
* cosine(a) * 100 = {100, 96, 85, 69, 50, 31, 15, 4, 0, 4, 15, 31, 50, 69, 85, 96, 100}
* fractions_percent(a) = round(50 + (cosine * 50))
*/
fraction_TL = 0;
fraction_TR = 0;
fraction_TL = fraction_TR = 0;
if (direction >= DIRECTION_LEFT && direction <= DIRECTION_RIGHT) {
index_left = (direction - DIRECTION_LEFT) >> 11;
index_right = proportions_idx_max - index_left;
u8 index_left = (direction - DIRECTION_LEFT) >> 11;
u8 index_right = proportions_idx_max - index_left;
fraction_TL = fractions_percent[index_left];
fraction_TR = fractions_percent[index_right];
}

/* we want to keep the rumbling at the triggers below the maximum
* of the weak and strong main rumble
*/
max = mag_main_right > mag_main_left ? mag_main_right : mag_main_left;
max_unscaled = weak > strong ? weak : strong;

/* the user can change the damping at runtime, hence check the range */
trigger_rumble_damping_nonzero
= param_trigger_rumble_damping == 0 ? 1 : param_trigger_rumble_damping;
max_damped = max_unscaled / trigger_rumble_damping_nonzero;
mag_trigger_left = (u8)((max_damped * fraction_TL) / 0xFFFF);
mag_trigger_right = (u8)((max_damped * fraction_TR) / 0xFFFF);

ff_active = FF_ENABLE_ALL;
if (param_disable_ff & PARAM_DISABLE_FF_TRIGGER)
ff_active &= ~(FF_ENABLE_LEFT_TRIGGER | FF_ENABLE_RIGHT_TRIGGER);
if (param_disable_ff & PARAM_DISABLE_FF_MAIN)
ff_active &= ~(FF_ENABLE_LEFT | FF_ENABLE_RIGHT);

create_ff_pck(
&ff_pck, 0x03,
ff_active,
mag_trigger_left, mag_trigger_right,
mag_main_left, mag_main_right,
0);

hid_dbg_lvl(DBG_LVL_FEW, hdev,
"active: %#04x, max: %#04x, prop_left: %#04x, prop_right: %#04x, left trigger: %#04x, right: %#04x\n",
ff_active,
max, fraction_TL, fraction_TR,
ff_pck.ff.magnitude_left_trigger,
ff_pck.ff.magnitude_right_trigger);
if (param_trigger_rumble_damping > 0) {
max_damped = max_unscaled / param_trigger_rumble_damping;
}
else {
max_damped = max_unscaled;
}

hid_hw_output_report(hdev, (u8 *)&ff_pck, sizeof(ff_pck));
/* calculate the physical magnitudes, scale from 16 bit to 0..100 */
xdata->ff.magnitude_left_trigger = (u8)((max_damped * fraction_TL) / U16_MAX);
xdata->ff.magnitude_right_trigger = (u8)((max_damped * fraction_TR) / U16_MAX);

/* schedule writing a rumble report to the controller */
schedule_work(&xdata->ff_worker);
return 0;
}

Expand All @@ -332,7 +331,9 @@ static void xpadneo_welcome_rumble(struct hid_device *hdev)
ff_pck.ff.magnitude_left = 20;
ff_pck.ff.magnitude_right_trigger = 10;
ff_pck.ff.magnitude_left_trigger = 10;
ff_pck.ff.duration = 33;
ff_pck.ff.pulse_sustain_10ms = 5;
ff_pck.ff.pulse_release_10ms = 5;
ff_pck.ff.loop_count = 3;

ff_pck.ff.enable = FF_ENABLE_RIGHT;
hid_hw_output_report(hdev, (u8 *)&ff_pck, sizeof(ff_pck));
Expand All @@ -354,21 +355,22 @@ static void xpadneo_welcome_rumble(struct hid_device *hdev)
*/
static int xpadneo_initDevice(struct hid_device *hdev)
{
int error;

struct xpadneo_devdata *xdata = hid_get_drvdata(hdev);
struct input_dev *idev = xdata->idev;

INIT_WORK(&xdata->ff_worker, xpadneo_ff_worker);
xdata->output_report_dmabuf = devm_kzalloc(&hdev->dev,
sizeof(struct ff_report),
GFP_KERNEL);
if (xdata->output_report_dmabuf == NULL)
return -ENOMEM;

/* 'HELLO' FROM THE OTHER SIDE */
if (!param_disable_ff) xpadneo_welcome_rumble(hdev);

/* Init Input System for Force Feedback (FF) */
input_set_capability(idev, EV_FF, FF_RUMBLE);
error = input_ff_create_memless(idev, NULL, xpadneo_ff_play);
if (error)
return error;

return 0;
return input_ff_create_memless(idev, NULL, xpadneo_ff_play);
}


Expand Down Expand Up @@ -1254,6 +1256,7 @@ static void xpadneo_remove_device(struct hid_device *hdev)
{
struct xpadneo_devdata *xdata = hid_get_drvdata(hdev);

cancel_work_sync(&xdata->ff_worker);
hid_hw_close(hdev);

/* Cleaning up here */
Expand Down

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