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Code Issues Releases Wiki Activity

media: pwm-ir-tx: Trigger edges from hrtimer interrupt context

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This makes the generated IR much more precise. Before this change, the
driver is unreliable and many users opted to use gpio-ir-tx instead.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Sean Young 2023-12-19 16:30:29 +00:00 committed by Thierry Reding
parent fcc7607293
commit 363d0e5628
1 changed files with 78 additions and 5 deletions
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83
drivers/media/rc/pwm-ir-tx.c
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@ -10,6 +10,8 @@
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/hrtimer.h>
#include <linux/completion.h>
#include <media/rc-core.h>
#define DRIVER_NAME "pwm-ir-tx"
@ -17,8 +19,14 @@
struct pwm_ir {
struct pwm_device *pwm;
unsigned int carrier;
unsigned int duty_cycle;
struct hrtimer timer;
struct completion tx_done;
struct pwm_state *state;
u32 carrier;
u32 duty_cycle;
const unsigned int *txbuf;
unsigned int txbuf_len;
unsigned int txbuf_index;
};
static const struct of_device_id pwm_ir_of_match[] = {
@ -49,8 +57,8 @@ static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier)
return 0;
}
static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
unsigned int count)
static int pwm_ir_tx_sleep(struct rc_dev *dev, unsigned int *txbuf,
unsigned int count)
{
struct pwm_ir *pwm_ir = dev->priv;
struct pwm_device *pwm = pwm_ir->pwm;
@ -82,6 +90,62 @@ static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
return count;
}
static int pwm_ir_tx_atomic(struct rc_dev *dev, unsigned int *txbuf,
unsigned int count)
{
struct pwm_ir *pwm_ir = dev->priv;
struct pwm_device *pwm = pwm_ir->pwm;
struct pwm_state state;
pwm_init_state(pwm, &state);
state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100);
pwm_ir->txbuf = txbuf;
pwm_ir->txbuf_len = count;
pwm_ir->txbuf_index = 0;
pwm_ir->state = &state;
hrtimer_start(&pwm_ir->timer, 0, HRTIMER_MODE_REL);
wait_for_completion(&pwm_ir->tx_done);
return count;
}
static enum hrtimer_restart pwm_ir_timer(struct hrtimer *timer)
{
struct pwm_ir *pwm_ir = container_of(timer, struct pwm_ir, timer);
ktime_t now;
/*
* If we happen to hit an odd latency spike, loop through the
* pulses until we catch up.
*/
do {
u64 ns;
pwm_ir->state->enabled = !(pwm_ir->txbuf_index % 2);
pwm_apply_atomic(pwm_ir->pwm, pwm_ir->state);
if (pwm_ir->txbuf_index >= pwm_ir->txbuf_len) {
complete(&pwm_ir->tx_done);
return HRTIMER_NORESTART;
}
ns = US_TO_NS(pwm_ir->txbuf[pwm_ir->txbuf_index]);
hrtimer_add_expires_ns(timer, ns);
pwm_ir->txbuf_index++;
now = timer->base->get_time();
} while (hrtimer_get_expires_tv64(timer) < now);
return HRTIMER_RESTART;
}
static int pwm_ir_probe(struct platform_device *pdev)
{
struct pwm_ir *pwm_ir;
@ -103,10 +167,19 @@ static int pwm_ir_probe(struct platform_device *pdev)
if (!rcdev)
return -ENOMEM;
if (pwm_might_sleep(pwm_ir->pwm)) {
dev_info(&pdev->dev, "TX will not be accurate as PWM device might sleep\n");
rcdev->tx_ir = pwm_ir_tx_sleep;
} else {
init_completion(&pwm_ir->tx_done);
hrtimer_init(&pwm_ir->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
pwm_ir->timer.function = pwm_ir_timer;
rcdev->tx_ir = pwm_ir_tx_atomic;
}
rcdev->priv = pwm_ir;
rcdev->driver_name = DRIVER_NAME;
rcdev->device_name = DEVICE_NAME;
rcdev->tx_ir = pwm_ir_tx;
rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
rcdev->s_tx_carrier = pwm_ir_set_carrier;