| Message ID | 88fdb3a200989458c6f95c26fa9bb84c1e864798.1701248996.git.sean@mess.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Improve pwm-ir-tx precision | expand |
On Wed, Nov 29, 2023 at 09:13:37AM +0000, Sean Young wrote: > 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> > --- > drivers/media/rc/pwm-ir-tx.c | 79 ++++++++++++++++++++++++++++++++++-- > 1 file changed, 76 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/rc/pwm-ir-tx.c b/drivers/media/rc/pwm-ir-tx.c > index cf51e2760975..8575c4596d7b 100644 > --- a/drivers/media/rc/pwm-ir-tx.c > +++ b/drivers/media/rc/pwm-ir-tx.c > @@ -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; > + uint *txbuf; Maybe mark this as const to signal that it's not going to get modified? > + uint txbuf_len; > + uint txbuf_index; uint is rather rare. Or so I thought. There seem to be quite a few occurrences throughout the kernel. I'd still prefer unsigned int over this abbreviated form, but ultimately up to you and Mauro to decide. > }; > > static const struct of_device_id pwm_ir_of_match[] = { > @@ -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_is_atomic(pwm_ir->pwm)) { > + 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; > + } else { > + dev_info(&pdev->dev, "tx will not be accurate as pwm device does not support atomic mode"); s/tx/TX and s/pwm/PWM/? Also, I'm a bit unhappy about "atomic mode" here because the term is overloaded in PWM. If you call pwm_appy_*() then by definition it's going to be "atomic" in the "atomic state" sense. So maybe switch to something like: "TX will not be accurate as PWM device might sleep" ? Thierry
On Fri, Dec 08, 2023 at 05:29:55PM +0100, Thierry Reding wrote: > On Wed, Nov 29, 2023 at 09:13:37AM +0000, Sean Young wrote: > > 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> > > --- > > drivers/media/rc/pwm-ir-tx.c | 79 ++++++++++++++++++++++++++++++++++-- > > 1 file changed, 76 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/media/rc/pwm-ir-tx.c b/drivers/media/rc/pwm-ir-tx.c > > index cf51e2760975..8575c4596d7b 100644 > > --- a/drivers/media/rc/pwm-ir-tx.c > > +++ b/drivers/media/rc/pwm-ir-tx.c > > @@ -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; > > + uint *txbuf; > > Maybe mark this as const to signal that it's not going to get modified? Ah nice, I usually forget const. > > + uint txbuf_len; > > + uint txbuf_index; > > uint is rather rare. Or so I thought. There seem to be quite a few > occurrences throughout the kernel. I'd still prefer unsigned int over > this abbreviated form, but ultimately up to you and Mauro to decide. Yes, unsigned int is used a lot more. Changed. > > 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_is_atomic(pwm_ir->pwm)) { > > + 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; > > + } else { > > + dev_info(&pdev->dev, "tx will not be accurate as pwm device does not support atomic mode"); > > s/tx/TX and s/pwm/PWM/? Also, I'm a bit unhappy about "atomic mode" here > because the term is overloaded in PWM. If you call pwm_appy_*() then by > definition it's going to be "atomic" in the "atomic state" sense. So > maybe switch to something like: > > "TX will not be accurate as PWM device might sleep" > > ? Very nice, changed. Thanks Sean
diff --git a/drivers/media/rc/pwm-ir-tx.c b/drivers/media/rc/pwm-ir-tx.c index cf51e2760975..8575c4596d7b 100644 --- a/drivers/media/rc/pwm-ir-tx.c +++ b/drivers/media/rc/pwm-ir-tx.c @@ -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; + uint *txbuf; + uint txbuf_len; + uint txbuf_index; }; static const struct of_device_id pwm_ir_of_match[] = { @@ -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_is_atomic(pwm_ir->pwm)) { + 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; + } else { + dev_info(&pdev->dev, "tx will not be accurate as pwm device does not support atomic mode"); + rcdev->tx_ir = pwm_ir_tx; + } + 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;
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> --- drivers/media/rc/pwm-ir-tx.c | 79 ++++++++++++++++++++++++++++++++++-- 1 file changed, 76 insertions(+), 3 deletions(-)