From: Sean Young <sean@mess.org>
To: linux-media@vger.kernel.org, linux-pwm@vger.kernel.org,
"Ivaylo Dimitrov" <ivo.g.dimitrov.75@gmail.com>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Sean Young" <sean@mess.org>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH v10 6/6] media: pwm-ir-tx: Trigger edges from hrtimer interrupt context
Date: Tue, 19 Dec 2023 16:30:29 +0000 [thread overview]
Message-ID: <1a5750d4eb3e4f777a123b094fdd66d3b16d2b9d.1703003288.git.sean@mess.org> (raw)
In-Reply-To: <cover.1703003288.git.sean@mess.org>
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 | 83 +++++++++++++++++++++++++++++++++---
1 file changed, 78 insertions(+), 5 deletions(-)
diff --git a/drivers/media/rc/pwm-ir-tx.c b/drivers/media/rc/pwm-ir-tx.c
index cf51e2760975..fe368aebbc13 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;
+ 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;
--
2.43.0
next prev parent reply other threads:[~2023-12-19 16:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-19 16:30 [PATCH v10 0/6] Improve pwm-ir-tx precision Sean Young
2023-12-19 16:30 ` [PATCH v10 1/6] pwm: Rename pwm_apply_state() to pwm_apply_might_sleep() Sean Young
2023-12-19 16:30 ` [PATCH v10 2/6] pwm: Replace ENOTSUPP with EOPNOTSUPP Sean Young
2023-12-19 17:01 ` Uwe Kleine-König
2023-12-19 16:30 ` [PATCH v10 3/6] pwm: renesas: Remove unused include Sean Young
2023-12-19 16:30 ` [PATCH v10 4/6] pwm: Make it possible to apply PWM changes in atomic context Sean Young
2023-12-20 10:31 ` Uwe Kleine-König
2023-12-19 16:30 ` [PATCH v10 5/6] pwm: bcm2835: Allow PWM driver to be used " Sean Young
2023-12-19 16:58 ` Uwe Kleine-König
2023-12-19 16:30 ` Sean Young [this message]
2023-12-20 16:06 ` (subset) [PATCH v10 0/6] Improve pwm-ir-tx precision Thierry Reding
2023-12-20 16:09 ` Thierry Reding
2023-12-21 9:09 ` Sean Young
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