[PATCH v8 0/6] Improve pwm-ir-tx precision

[PATCH v8 0/6] Improve pwm-ir-tx precision

[Sean Young]

The pwm-ir-tx driver has to turn the pwm signal on and off, and suffers
from delays as this is done in process context. Make this work in atomic
context.

changes:

v8:
 - Uwe Kleine-König review comments
 - Minor cleanups

v7:
 - Thierry Reding review comments
 - Minor cleanups
 - rebase

v6:
 - Rename pwm_apply_cansleep() to pwm_apply_might_sleep()
 - rebase

v5:
 - Use dev_err_probe() as Uwe suggested
 - rebase

v4:
 - Split out the pwm_apply_state() rename into seperate commit
 - Atomic pwm function is called pwm_apply_atomic() and sleeping
   counterpart pwm_apply_cansleep()
 - Fix commit messages

v3:
 - Renamed pwm_apply_state() to pwm_apply_cansleep()
 - Moved pwm atomic to struct pwm_chip
 - Fixed pwm docs
 - Other minor code review comments

v2:
 - Simplified the pwm ir tx based on Ivaylo Dimitrov suggestions
 - Renamed pwm_can_sleep() to pwm_is_atomic
 - Fix sleeping issue in pwm-bcm2835 (clk_get_rate() can sleep)
 - use non_block_start() in pwm to check atomic-ness

Sean Young (6):
  pwm: Rename pwm_apply_state() to pwm_apply_might_sleep()
  pwm: Replace ENOTSUPP with EOPNOTSUPP
  pwm: renesas: Remove unused include
  pwm: Make it possible to apply PWM changes in atomic context
  pwm: bcm2835: Allow PWM driver to be used in atomic context
  media: pwm-ir-tx: Trigger edges from hrtimer interrupt context


 Documentation/driver-api/pwm.rst              | 17 +++-
 MAINTAINERS                                   |  2 +-
 .../gpu/drm/i915/display/intel_backlight.c    |  6 +-
 drivers/gpu/drm/solomon/ssd130x.c             |  2 +-
 drivers/hwmon/pwm-fan.c                       |  8 +-
 drivers/input/misc/da7280.c                   |  4 +-
 drivers/input/misc/pwm-beeper.c               |  4 +-
 drivers/input/misc/pwm-vibra.c                |  8 +-
 drivers/leds/leds-pwm.c                       |  2 +-
 drivers/leds/rgb/leds-pwm-multicolor.c        |  4 +-
 drivers/media/rc/pwm-ir-tx.c                  | 87 +++++++++++++++++--
 drivers/platform/x86/lenovo-yogabook.c        |  2 +-
 drivers/pwm/core.c                            | 77 ++++++++++++----
 drivers/pwm/pwm-bcm2835.c                     | 31 ++++---
 drivers/pwm/pwm-renesas-tpu.c                 |  1 -
 drivers/pwm/pwm-twl-led.c                     |  2 +-
 drivers/pwm/pwm-vt8500.c                      |  2 +-
 drivers/pwm/sysfs.c                           | 10 +--
 drivers/regulator/pwm-regulator.c             |  4 +-
 drivers/video/backlight/lm3630a_bl.c          |  2 +-
 drivers/video/backlight/lp855x_bl.c           |  2 +-
 drivers/video/backlight/pwm_bl.c              | 12 +--
 drivers/video/fbdev/ssd1307fb.c               |  2 +-
 include/linux/pwm.h                           | 57 ++++++++----
 24 files changed, 253 insertions(+), 95 deletions(-)

-- 
2.43.0

[PATCH v8 1/6] pwm: Rename pwm_apply_state() to pwm_apply_might_sleep()

[Sean Young]

In order to introduce a pwm api which can be used from atomic context,
we will need two functions for applying pwm changes:

	int pwm_apply_might_sleep(struct pwm *, struct pwm_state *);
	int pwm_apply_atomic(struct pwm *, struct pwm_state *);

This commit just deals with renaming pwm_apply_state(), a following
commit will introduce the pwm_apply_atomic() function.

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> # for input
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Lee Jones <lee@kernel.org>
Signed-off-by: Sean Young <sean@mess.org>
---
 Documentation/driver-api/pwm.rst              |  8 +++---
 MAINTAINERS                                   |  2 +-
 .../gpu/drm/i915/display/intel_backlight.c    |  6 ++--
 drivers/gpu/drm/solomon/ssd130x.c             |  2 +-
 drivers/hwmon/pwm-fan.c                       |  8 +++---
 drivers/input/misc/da7280.c                   |  4 +--
 drivers/input/misc/pwm-beeper.c               |  4 +--
 drivers/input/misc/pwm-vibra.c                |  8 +++---
 drivers/leds/leds-pwm.c                       |  2 +-
 drivers/leds/rgb/leds-pwm-multicolor.c        |  4 +--
 drivers/media/rc/pwm-ir-tx.c                  |  4 +--
 drivers/platform/x86/lenovo-yogabook.c        |  2 +-
 drivers/pwm/core.c                            | 18 ++++++------
 drivers/pwm/pwm-twl-led.c                     |  2 +-
 drivers/pwm/pwm-vt8500.c                      |  2 +-
 drivers/pwm/sysfs.c                           | 10 +++----
 drivers/regulator/pwm-regulator.c             |  4 +--
 drivers/video/backlight/lm3630a_bl.c          |  2 +-
 drivers/video/backlight/lp855x_bl.c           |  2 +-
 drivers/video/backlight/pwm_bl.c              | 12 ++++----
 drivers/video/fbdev/ssd1307fb.c               |  2 +-
 include/linux/pwm.h                           | 28 +++++++++----------
 22 files changed, 68 insertions(+), 68 deletions(-)

diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst
index bb264490a87a1..f1d8197c8c430 100644
--- a/Documentation/driver-api/pwm.rst
+++ b/Documentation/driver-api/pwm.rst
@@ -41,7 +41,7 @@ the getter, devm_pwm_get() and devm_fwnode_pwm_get(), also exist.
 
 After being requested, a PWM has to be configured using::
 
-	int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state);
+	int pwm_apply_might_sleep(struct pwm_device *pwm, struct pwm_state *state);
 
 This API controls both the PWM period/duty_cycle config and the
 enable/disable state.
@@ -57,13 +57,13 @@ If supported by the driver, the signal can be optimized, for example to improve
 EMI by phase shifting the individual channels of a chip.
 
 The pwm_config(), pwm_enable() and pwm_disable() functions are just wrappers
-around pwm_apply_state() and should not be used if the user wants to change
+around pwm_apply_might_sleep() and should not be used if the user wants to change
 several parameter at once. For example, if you see pwm_config() and
 pwm_{enable,disable}() calls in the same function, this probably means you
-should switch to pwm_apply_state().
+should switch to pwm_apply_might_sleep().
 
 The PWM user API also allows one to query the PWM state that was passed to the
-last invocation of pwm_apply_state() using pwm_get_state(). Note this is
+last invocation of pwm_apply_might_sleep() using pwm_get_state(). Note this is
 different to what the driver has actually implemented if the request cannot be
 satisfied exactly with the hardware in use. There is currently no way for
 consumers to get the actually implemented settings.
diff --git a/MAINTAINERS b/MAINTAINERS
index 97f51d5ec1cfd..c584805952209 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17576,7 +17576,7 @@ F:	drivers/video/backlight/pwm_bl.c
 F:	include/dt-bindings/pwm/
 F:	include/linux/pwm.h
 F:	include/linux/pwm_backlight.h
-K:	pwm_(config|apply_state|ops)
+K:	pwm_(config|apply_might_sleep|ops)
 
 PXA GPIO DRIVER
 M:	Robert Jarzmik <robert.jarzmik@free.fr>
diff --git a/drivers/gpu/drm/i915/display/intel_backlight.c b/drivers/gpu/drm/i915/display/intel_backlight.c
index 2e8f17c045222..ff9b9918b0a13 100644
--- a/drivers/gpu/drm/i915/display/intel_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_backlight.c
@@ -274,7 +274,7 @@ static void ext_pwm_set_backlight(const struct drm_connector_state *conn_state,
 	struct intel_panel *panel = &to_intel_connector(conn_state->connector)->panel;
 
 	pwm_set_relative_duty_cycle(&panel->backlight.pwm_state, level, 100);
-	pwm_apply_state(panel->backlight.pwm, &panel->backlight.pwm_state);
+	pwm_apply_might_sleep(panel->backlight.pwm, &panel->backlight.pwm_state);
 }
 
 static void
@@ -427,7 +427,7 @@ static void ext_pwm_disable_backlight(const struct drm_connector_state *old_conn
 	intel_backlight_set_pwm_level(old_conn_state, level);
 
 	panel->backlight.pwm_state.enabled = false;
-	pwm_apply_state(panel->backlight.pwm, &panel->backlight.pwm_state);
+	pwm_apply_might_sleep(panel->backlight.pwm, &panel->backlight.pwm_state);
 }
 
 void intel_backlight_disable(const struct drm_connector_state *old_conn_state)
@@ -749,7 +749,7 @@ static void ext_pwm_enable_backlight(const struct intel_crtc_state *crtc_state,
 
 	pwm_set_relative_duty_cycle(&panel->backlight.pwm_state, level, 100);
 	panel->backlight.pwm_state.enabled = true;
-	pwm_apply_state(panel->backlight.pwm, &panel->backlight.pwm_state);
+	pwm_apply_might_sleep(panel->backlight.pwm, &panel->backlight.pwm_state);
 }
 
 static void __intel_backlight_enable(const struct intel_crtc_state *crtc_state,
diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index e0174f82e3537..cce043a4a1dcd 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -319,7 +319,7 @@ static int ssd130x_pwm_enable(struct ssd130x_device *ssd130x)
 
 	pwm_init_state(ssd130x->pwm, &pwmstate);
 	pwm_set_relative_duty_cycle(&pwmstate, 50, 100);
-	pwm_apply_state(ssd130x->pwm, &pwmstate);
+	pwm_apply_might_sleep(ssd130x->pwm, &pwmstate);
 
 	/* Enable the PWM */
 	pwm_enable(ssd130x->pwm);
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 6e4516c2ab894..b67bc9e833c01 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -151,7 +151,7 @@ static int pwm_fan_power_on(struct pwm_fan_ctx *ctx)
 	}
 
 	state->enabled = true;
-	ret = pwm_apply_state(ctx->pwm, state);
+	ret = pwm_apply_might_sleep(ctx->pwm, state);
 	if (ret) {
 		dev_err(ctx->dev, "failed to enable PWM\n");
 		goto disable_regulator;
@@ -181,7 +181,7 @@ static int pwm_fan_power_off(struct pwm_fan_ctx *ctx)
 
 	state->enabled = false;
 	state->duty_cycle = 0;
-	ret = pwm_apply_state(ctx->pwm, state);
+	ret = pwm_apply_might_sleep(ctx->pwm, state);
 	if (ret) {
 		dev_err(ctx->dev, "failed to disable PWM\n");
 		return ret;
@@ -207,7 +207,7 @@ static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
 
 		period = state->period;
 		state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
-		ret = pwm_apply_state(ctx->pwm, state);
+		ret = pwm_apply_might_sleep(ctx->pwm, state);
 		if (ret)
 			return ret;
 		ret = pwm_fan_power_on(ctx);
@@ -278,7 +278,7 @@ static int pwm_fan_update_enable(struct pwm_fan_ctx *ctx, long val)
 						    state,
 						    &enable_regulator);
 
-			pwm_apply_state(ctx->pwm, state);
+			pwm_apply_might_sleep(ctx->pwm, state);
 			pwm_fan_switch_power(ctx, enable_regulator);
 			pwm_fan_update_state(ctx, 0);
 		}
diff --git a/drivers/input/misc/da7280.c b/drivers/input/misc/da7280.c
index ce82548916bbc..c1fa75c0f970a 100644
--- a/drivers/input/misc/da7280.c
+++ b/drivers/input/misc/da7280.c
@@ -352,7 +352,7 @@ static int da7280_haptic_set_pwm(struct da7280_haptic *haptics, bool enabled)
 		state.duty_cycle = period_mag_multi;
 	}
 
-	error = pwm_apply_state(haptics->pwm_dev, &state);
+	error = pwm_apply_might_sleep(haptics->pwm_dev, &state);
 	if (error)
 		dev_err(haptics->dev, "Failed to apply pwm state: %d\n", error);
 
@@ -1175,7 +1175,7 @@ static int da7280_probe(struct i2c_client *client)
 		/* Sync up PWM state and ensure it is off. */
 		pwm_init_state(haptics->pwm_dev, &state);
 		state.enabled = false;
-		error = pwm_apply_state(haptics->pwm_dev, &state);
+		error = pwm_apply_might_sleep(haptics->pwm_dev, &state);
 		if (error) {
 			dev_err(dev, "Failed to apply PWM state: %d\n", error);
 			return error;
diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
index 1e731d8397c6f..5b9aedf4362f4 100644
--- a/drivers/input/misc/pwm-beeper.c
+++ b/drivers/input/misc/pwm-beeper.c
@@ -39,7 +39,7 @@ static int pwm_beeper_on(struct pwm_beeper *beeper, unsigned long period)
 	state.period = period;
 	pwm_set_relative_duty_cycle(&state, 50, 100);
 
-	error = pwm_apply_state(beeper->pwm, &state);
+	error = pwm_apply_might_sleep(beeper->pwm, &state);
 	if (error)
 		return error;
 
@@ -138,7 +138,7 @@ static int pwm_beeper_probe(struct platform_device *pdev)
 	/* Sync up PWM state and ensure it is off. */
 	pwm_init_state(beeper->pwm, &state);
 	state.enabled = false;
-	error = pwm_apply_state(beeper->pwm, &state);
+	error = pwm_apply_might_sleep(beeper->pwm, &state);
 	if (error) {
 		dev_err(dev, "failed to apply initial PWM state: %d\n",
 			error);
diff --git a/drivers/input/misc/pwm-vibra.c b/drivers/input/misc/pwm-vibra.c
index acac79c488aa1..3e5ed685ed8f5 100644
--- a/drivers/input/misc/pwm-vibra.c
+++ b/drivers/input/misc/pwm-vibra.c
@@ -56,7 +56,7 @@ static int pwm_vibrator_start(struct pwm_vibrator *vibrator)
 	pwm_set_relative_duty_cycle(&state, vibrator->level, 0xffff);
 	state.enabled = true;
 
-	err = pwm_apply_state(vibrator->pwm, &state);
+	err = pwm_apply_might_sleep(vibrator->pwm, &state);
 	if (err) {
 		dev_err(pdev, "failed to apply pwm state: %d\n", err);
 		return err;
@@ -67,7 +67,7 @@ static int pwm_vibrator_start(struct pwm_vibrator *vibrator)
 		state.duty_cycle = vibrator->direction_duty_cycle;
 		state.enabled = true;
 
-		err = pwm_apply_state(vibrator->pwm_dir, &state);
+		err = pwm_apply_might_sleep(vibrator->pwm_dir, &state);
 		if (err) {
 			dev_err(pdev, "failed to apply dir-pwm state: %d\n", err);
 			pwm_disable(vibrator->pwm);
@@ -160,7 +160,7 @@ static int pwm_vibrator_probe(struct platform_device *pdev)
 	/* Sync up PWM state and ensure it is off. */
 	pwm_init_state(vibrator->pwm, &state);
 	state.enabled = false;
-	err = pwm_apply_state(vibrator->pwm, &state);
+	err = pwm_apply_might_sleep(vibrator->pwm, &state);
 	if (err) {
 		dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
 			err);
@@ -174,7 +174,7 @@ static int pwm_vibrator_probe(struct platform_device *pdev)
 		/* Sync up PWM state and ensure it is off. */
 		pwm_init_state(vibrator->pwm_dir, &state);
 		state.enabled = false;
-		err = pwm_apply_state(vibrator->pwm_dir, &state);
+		err = pwm_apply_might_sleep(vibrator->pwm_dir, &state);
 		if (err) {
 			dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
 				err);
diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index 2b3bf1353b707..4e3936a39d0ed 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -54,7 +54,7 @@ static int led_pwm_set(struct led_classdev *led_cdev,
 
 	led_dat->pwmstate.duty_cycle = duty;
 	led_dat->pwmstate.enabled = true;
-	return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
+	return pwm_apply_might_sleep(led_dat->pwm, &led_dat->pwmstate);
 }
 
 __attribute__((nonnull))
diff --git a/drivers/leds/rgb/leds-pwm-multicolor.c b/drivers/leds/rgb/leds-pwm-multicolor.c
index 46cd062b8b24c..e1a81e0109e8a 100644
--- a/drivers/leds/rgb/leds-pwm-multicolor.c
+++ b/drivers/leds/rgb/leds-pwm-multicolor.c
@@ -51,8 +51,8 @@ static int led_pwm_mc_set(struct led_classdev *cdev,
 
 		priv->leds[i].state.duty_cycle = duty;
 		priv->leds[i].state.enabled = duty > 0;
-		ret = pwm_apply_state(priv->leds[i].pwm,
-				      &priv->leds[i].state);
+		ret = pwm_apply_might_sleep(priv->leds[i].pwm,
+					    &priv->leds[i].state);
 		if (ret)
 			break;
 	}
diff --git a/drivers/media/rc/pwm-ir-tx.c b/drivers/media/rc/pwm-ir-tx.c
index c5f37c03af9c9..cf51e27609759 100644
--- a/drivers/media/rc/pwm-ir-tx.c
+++ b/drivers/media/rc/pwm-ir-tx.c
@@ -68,7 +68,7 @@ static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
 
 	for (i = 0; i < count; i++) {
 		state.enabled = !(i % 2);
-		pwm_apply_state(pwm, &state);
+		pwm_apply_might_sleep(pwm, &state);
 
 		edge = ktime_add_us(edge, txbuf[i]);
 		delta = ktime_us_delta(edge, ktime_get());
@@ -77,7 +77,7 @@ static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
 	}
 
 	state.enabled = false;
-	pwm_apply_state(pwm, &state);
+	pwm_apply_might_sleep(pwm, &state);
 
 	return count;
 }
diff --git a/drivers/platform/x86/lenovo-yogabook.c b/drivers/platform/x86/lenovo-yogabook.c
index b8d0239192cbf..fd62bf746ebde 100644
--- a/drivers/platform/x86/lenovo-yogabook.c
+++ b/drivers/platform/x86/lenovo-yogabook.c
@@ -435,7 +435,7 @@ static int yogabook_pdev_set_kbd_backlight(struct yogabook_data *data, u8 level)
 		.enabled = level,
 	};
 
-	pwm_apply_state(data->kbd_bl_pwm, &state);
+	pwm_apply_might_sleep(data->kbd_bl_pwm, &state);
 	gpiod_set_value(data->kbd_bl_led_enable, level ? 1 : 0);
 	return 0;
 }
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index f60b715abe62b..c2d78136625d5 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -326,8 +326,8 @@ struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 }
 EXPORT_SYMBOL_GPL(pwm_request_from_chip);
 
-static void pwm_apply_state_debug(struct pwm_device *pwm,
-				  const struct pwm_state *state)
+static void pwm_apply_debug(struct pwm_device *pwm,
+			    const struct pwm_state *state)
 {
 	struct pwm_state *last = &pwm->last;
 	struct pwm_chip *chip = pwm->chip;
@@ -433,11 +433,11 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 }
 
 /**
- * pwm_apply_state() - atomically apply a new state to a PWM device
+ * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
  * @pwm: PWM device
  * @state: new state to apply
  */
-int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
+int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
 {
 	struct pwm_chip *chip;
 	int err;
@@ -445,7 +445,7 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
 	/*
 	 * Some lowlevel driver's implementations of .apply() make use of
 	 * mutexes, also with some drivers only returning when the new
-	 * configuration is active calling pwm_apply_state() from atomic context
+	 * configuration is active calling pwm_apply_might_sleep() from atomic context
 	 * is a bad idea. So make it explicit that calling this function might
 	 * sleep.
 	 */
@@ -475,11 +475,11 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
 	 * only do this after pwm->state was applied as some
 	 * implementations of .get_state depend on this
 	 */
-	pwm_apply_state_debug(pwm, state);
+	pwm_apply_debug(pwm, state);
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(pwm_apply_state);
+EXPORT_SYMBOL_GPL(pwm_apply_might_sleep);
 
 /**
  * pwm_capture() - capture and report a PWM signal
@@ -537,7 +537,7 @@ int pwm_adjust_config(struct pwm_device *pwm)
 		state.period = pargs.period;
 		state.polarity = pargs.polarity;
 
-		return pwm_apply_state(pwm, &state);
+		return pwm_apply_might_sleep(pwm, &state);
 	}
 
 	/*
@@ -560,7 +560,7 @@ int pwm_adjust_config(struct pwm_device *pwm)
 		state.duty_cycle = state.period - state.duty_cycle;
 	}
 
-	return pwm_apply_state(pwm, &state);
+	return pwm_apply_might_sleep(pwm, &state);
 }
 EXPORT_SYMBOL_GPL(pwm_adjust_config);
 
diff --git a/drivers/pwm/pwm-twl-led.c b/drivers/pwm/pwm-twl-led.c
index 8a870d0db3c69..c670ccb816536 100644
--- a/drivers/pwm/pwm-twl-led.c
+++ b/drivers/pwm/pwm-twl-led.c
@@ -172,7 +172,7 @@ static int twl4030_pwmled_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * We cannot skip calling ->config even if state->period ==
 	 * pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
 	 * because we might have exited early in the last call to
-	 * pwm_apply_state because of !state->enabled and so the two values in
+	 * pwm_apply_might_sleep because of !state->enabled and so the two values in
 	 * pwm->state might not be configured in hardware.
 	 */
 	ret = twl4030_pwmled_config(chip, pwm,
diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
index bdea60389487e..7bfeacee05d0f 100644
--- a/drivers/pwm/pwm-vt8500.c
+++ b/drivers/pwm/pwm-vt8500.c
@@ -206,7 +206,7 @@ static int vt8500_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * We cannot skip calling ->config even if state->period ==
 	 * pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
 	 * because we might have exited early in the last call to
-	 * pwm_apply_state because of !state->enabled and so the two values in
+	 * pwm_apply_might_sleep because of !state->enabled and so the two values in
 	 * pwm->state might not be configured in hardware.
 	 */
 	err = vt8500_pwm_config(chip, pwm, state->duty_cycle, state->period);
diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 4edb994fa2e12..1698609d91c8a 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -62,7 +62,7 @@ static ssize_t period_store(struct device *child,
 	mutex_lock(&export->lock);
 	pwm_get_state(pwm, &state);
 	state.period = val;
-	ret = pwm_apply_state(pwm, &state);
+	ret = pwm_apply_might_sleep(pwm, &state);
 	mutex_unlock(&export->lock);
 
 	return ret ? : size;
@@ -97,7 +97,7 @@ static ssize_t duty_cycle_store(struct device *child,
 	mutex_lock(&export->lock);
 	pwm_get_state(pwm, &state);
 	state.duty_cycle = val;
-	ret = pwm_apply_state(pwm, &state);
+	ret = pwm_apply_might_sleep(pwm, &state);
 	mutex_unlock(&export->lock);
 
 	return ret ? : size;
@@ -144,7 +144,7 @@ static ssize_t enable_store(struct device *child,
 		goto unlock;
 	}
 
-	ret = pwm_apply_state(pwm, &state);
+	ret = pwm_apply_might_sleep(pwm, &state);
 
 unlock:
 	mutex_unlock(&export->lock);
@@ -194,7 +194,7 @@ static ssize_t polarity_store(struct device *child,
 	mutex_lock(&export->lock);
 	pwm_get_state(pwm, &state);
 	state.polarity = polarity;
-	ret = pwm_apply_state(pwm, &state);
+	ret = pwm_apply_might_sleep(pwm, &state);
 	mutex_unlock(&export->lock);
 
 	return ret ? : size;
@@ -401,7 +401,7 @@ static int pwm_class_apply_state(struct pwm_export *export,
 				 struct pwm_device *pwm,
 				 struct pwm_state *state)
 {
-	int ret = pwm_apply_state(pwm, state);
+	int ret = pwm_apply_might_sleep(pwm, state);
 
 	/* release lock taken in pwm_class_get_state */
 	mutex_unlock(&export->lock);
diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
index 2aff6db748e2c..698c420e0869b 100644
--- a/drivers/regulator/pwm-regulator.c
+++ b/drivers/regulator/pwm-regulator.c
@@ -90,7 +90,7 @@ static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev,
 	pwm_set_relative_duty_cycle(&pstate,
 			drvdata->duty_cycle_table[selector].dutycycle, 100);
 
-	ret = pwm_apply_state(drvdata->pwm, &pstate);
+	ret = pwm_apply_might_sleep(drvdata->pwm, &pstate);
 	if (ret) {
 		dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
 		return ret;
@@ -216,7 +216,7 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
 
 	pwm_set_relative_duty_cycle(&pstate, dutycycle, duty_unit);
 
-	ret = pwm_apply_state(drvdata->pwm, &pstate);
+	ret = pwm_apply_might_sleep(drvdata->pwm, &pstate);
 	if (ret) {
 		dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
 		return ret;
diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index 8fcb62be597b8..a3412c936ca28 100644
--- a/drivers/video/backlight/lm3630a_bl.c
+++ b/drivers/video/backlight/lm3630a_bl.c
@@ -180,7 +180,7 @@ static int lm3630a_pwm_ctrl(struct lm3630a_chip *pchip, int br, int br_max)
 
 	pchip->pwmd_state.enabled = pchip->pwmd_state.duty_cycle ? true : false;
 
-	return pwm_apply_state(pchip->pwmd, &pchip->pwmd_state);
+	return pwm_apply_might_sleep(pchip->pwmd, &pchip->pwmd_state);
 }
 
 /* update and get brightness */
diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
index da1f124db69c0..7075bfab59c4d 100644
--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -234,7 +234,7 @@ static int lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
 	state.duty_cycle = div_u64(br * state.period, max_br);
 	state.enabled = state.duty_cycle;
 
-	return pwm_apply_state(lp->pwm, &state);
+	return pwm_apply_might_sleep(lp->pwm, &state);
 }
 
 static int lp855x_bl_update_status(struct backlight_device *bl)
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 289bd9ce4d36d..35c716e9043c3 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -103,7 +103,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
 		pwm_get_state(pb->pwm, &state);
 		state.duty_cycle = compute_duty_cycle(pb, brightness, &state);
 		state.enabled = true;
-		pwm_apply_state(pb->pwm, &state);
+		pwm_apply_might_sleep(pb->pwm, &state);
 
 		pwm_backlight_power_on(pb);
 	} else {
@@ -120,7 +120,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
 		 * inactive output.
 		 */
 		state.enabled = !pb->power_supply && !pb->enable_gpio;
-		pwm_apply_state(pb->pwm, &state);
+		pwm_apply_might_sleep(pb->pwm, &state);
 	}
 
 	if (pb->notify_after)
@@ -528,7 +528,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 	if (!state.period && (data->pwm_period_ns > 0))
 		state.period = data->pwm_period_ns;
 
-	ret = pwm_apply_state(pb->pwm, &state);
+	ret = pwm_apply_might_sleep(pb->pwm, &state);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
 			ret);
@@ -633,7 +633,7 @@ static void pwm_backlight_remove(struct platform_device *pdev)
 	pwm_get_state(pb->pwm, &state);
 	state.duty_cycle = 0;
 	state.enabled = false;
-	pwm_apply_state(pb->pwm, &state);
+	pwm_apply_might_sleep(pb->pwm, &state);
 
 	if (pb->exit)
 		pb->exit(&pdev->dev);
@@ -649,7 +649,7 @@ static void pwm_backlight_shutdown(struct platform_device *pdev)
 	pwm_get_state(pb->pwm, &state);
 	state.duty_cycle = 0;
 	state.enabled = false;
-	pwm_apply_state(pb->pwm, &state);
+	pwm_apply_might_sleep(pb->pwm, &state);
 }
 
 #ifdef CONFIG_PM_SLEEP
@@ -673,7 +673,7 @@ static int pwm_backlight_suspend(struct device *dev)
 	pwm_get_state(pb->pwm, &state);
 	state.duty_cycle = 0;
 	state.enabled = false;
-	pwm_apply_state(pb->pwm, &state);
+	pwm_apply_might_sleep(pb->pwm, &state);
 
 	if (pb->notify_after)
 		pb->notify_after(pb->dev, 0);
diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index 5ae48e36fccb4..1a4f90ea7d5a8 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -347,7 +347,7 @@ static int ssd1307fb_init(struct ssd1307fb_par *par)
 
 		pwm_init_state(par->pwm, &pwmstate);
 		pwm_set_relative_duty_cycle(&pwmstate, 50, 100);
-		pwm_apply_state(par->pwm, &pwmstate);
+		pwm_apply_might_sleep(par->pwm, &pwmstate);
 
 		/* Enable the PWM */
 		pwm_enable(par->pwm);
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index f87655c06c825..b64b8a82415c4 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -92,8 +92,8 @@ struct pwm_device {
  * @state: state to fill with the current PWM state
  *
  * The returned PWM state represents the state that was applied by a previous call to
- * pwm_apply_state(). Drivers may have to slightly tweak that state before programming it to
- * hardware. If pwm_apply_state() was never called, this returns either the current hardware
+ * pwm_apply_might_sleep(). Drivers may have to slightly tweak that state before programming it to
+ * hardware. If pwm_apply_might_sleep() was never called, this returns either the current hardware
  * state (if supported) or the default settings.
  */
 static inline void pwm_get_state(const struct pwm_device *pwm,
@@ -157,20 +157,20 @@ static inline void pwm_get_args(const struct pwm_device *pwm,
 }
 
 /**
- * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
+ * pwm_init_state() - prepare a new state to be applied with pwm_apply_might_sleep()
  * @pwm: PWM device
  * @state: state to fill with the prepared PWM state
  *
  * This functions prepares a state that can later be tweaked and applied
- * to the PWM device with pwm_apply_state(). This is a convenient function
+ * to the PWM device with pwm_apply_might_sleep(). This is a convenient function
  * that first retrieves the current PWM state and the replaces the period
  * and polarity fields with the reference values defined in pwm->args.
  * Once the function returns, you can adjust the ->enabled and ->duty_cycle
- * fields according to your needs before calling pwm_apply_state().
+ * fields according to your needs before calling pwm_apply_might_sleep().
  *
  * ->duty_cycle is initially set to zero to avoid cases where the current
  * ->duty_cycle value exceed the pwm_args->period one, which would trigger
- * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
+ * an error if the user calls pwm_apply_might_sleep() without adjusting ->duty_cycle
  * first.
  */
 static inline void pwm_init_state(const struct pwm_device *pwm,
@@ -226,7 +226,7 @@ pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
  *
  * pwm_init_state(pwm, &state);
  * pwm_set_relative_duty_cycle(&state, 50, 100);
- * pwm_apply_state(pwm, &state);
+ * pwm_apply_might_sleep(pwm, &state);
  *
  * This functions returns -EINVAL if @duty_cycle and/or @scale are
  * inconsistent (@scale == 0 or @duty_cycle > @scale).
@@ -304,7 +304,7 @@ struct pwm_chip {
 
 #if IS_ENABLED(CONFIG_PWM)
 /* PWM user APIs */
-int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state);
+int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state);
 int pwm_adjust_config(struct pwm_device *pwm);
 
 /**
@@ -332,7 +332,7 @@ static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
 
 	state.duty_cycle = duty_ns;
 	state.period = period_ns;
-	return pwm_apply_state(pwm, &state);
+	return pwm_apply_might_sleep(pwm, &state);
 }
 
 /**
@@ -353,7 +353,7 @@ static inline int pwm_enable(struct pwm_device *pwm)
 		return 0;
 
 	state.enabled = true;
-	return pwm_apply_state(pwm, &state);
+	return pwm_apply_might_sleep(pwm, &state);
 }
 
 /**
@@ -372,7 +372,7 @@ static inline void pwm_disable(struct pwm_device *pwm)
 		return;
 
 	state.enabled = false;
-	pwm_apply_state(pwm, &state);
+	pwm_apply_might_sleep(pwm, &state);
 }
 
 /* PWM provider APIs */
@@ -403,8 +403,8 @@ struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
 				       struct fwnode_handle *fwnode,
 				       const char *con_id);
 #else
-static inline int pwm_apply_state(struct pwm_device *pwm,
-				  const struct pwm_state *state)
+static inline int pwm_apply_might_sleep(struct pwm_device *pwm,
+					const struct pwm_state *state)
 {
 	might_sleep();
 	return -ENOTSUPP;
@@ -521,7 +521,7 @@ static inline void pwm_apply_args(struct pwm_device *pwm)
 	state.period = pwm->args.period;
 	state.usage_power = false;
 
-	pwm_apply_state(pwm, &state);
+	pwm_apply_might_sleep(pwm, &state);
 }
 
 struct pwm_lookup {
-- 
2.43.0

[PATCH v8 2/6] pwm: Replace ENOTSUPP with EOPNOTSUPP

[Sean Young]

ENOTSUPP is not a standard error code and should be avoided.

Signed-off-by: Sean Young <sean@mess.org>
---
 include/linux/pwm.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index b64b8a82415c4..c9cb87b59ac80 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -407,12 +407,12 @@ static inline int pwm_apply_might_sleep(struct pwm_device *pwm,
 					const struct pwm_state *state)
 {
 	might_sleep();
-	return -ENOTSUPP;
+	return -EOPNOTSUPP;
 }
 
 static inline int pwm_adjust_config(struct pwm_device *pwm)
 {
-	return -ENOTSUPP;
+	return -EOPNOTSUPP;
 }
 
 static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
-- 
2.43.0

[PATCH v8 3/6] pwm: renesas: Remove unused include

[Sean Young]

No mutex is used in this driver.

Signed-off-by: Sean Young <sean@mess.org>
---
 drivers/pwm/pwm-renesas-tpu.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/pwm/pwm-renesas-tpu.c b/drivers/pwm/pwm-renesas-tpu.c
index ce92db1f85113..28265fdfc92a9 100644
--- a/drivers/pwm/pwm-renesas-tpu.c
+++ b/drivers/pwm/pwm-renesas-tpu.c
@@ -11,7 +11,6 @@
 #include <linux/init.h>
 #include <linux/ioport.h>
 #include <linux/module.h>
-#include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
-- 
2.43.0

[PATCH v8 4/6] pwm: Make it possible to apply PWM changes in atomic context

[Sean Young]

Some PWM devices require sleeping, for example if the pwm device is
connected over I2C. However, many PWM devices could be used from atomic
context, e.g. memory mapped PWM. This is useful for, for example, the
pwm-ir-tx driver which requires precise timing. Sleeping causes havoc
with the generated IR signal.

Since not all PWM devices can support atomic context, we also add a
pwm_might_sleep() function to check if is not supported.

Signed-off-by: Sean Young <sean@mess.org>
---
 Documentation/driver-api/pwm.rst |  9 +++++
 MAINTAINERS                      |  2 +-
 drivers/pwm/core.c               | 67 +++++++++++++++++++++++++-------
 include/linux/pwm.h              | 25 ++++++++++++
 4 files changed, 89 insertions(+), 14 deletions(-)

diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst
index f1d8197c8c430..3c28ccc4b6113 100644
--- a/Documentation/driver-api/pwm.rst
+++ b/Documentation/driver-api/pwm.rst
@@ -46,6 +46,15 @@ After being requested, a PWM has to be configured using::
 This API controls both the PWM period/duty_cycle config and the
 enable/disable state.
 
+PWM devices can be used from atomic context, if the PWM does not sleep. You
+can check if this the case with::
+
+        bool pwm_might_sleep(struct pwm_device *pwm);
+
+If false, the PWM can also be configured from atomic context with::
+
+	int pwm_apply_atomic(struct pwm_device *pwm, struct pwm_state *state);
+
 As a consumer, don't rely on the output's state for a disabled PWM. If it's
 easily possible, drivers are supposed to emit the inactive state, but some
 drivers cannot. If you rely on getting the inactive state, use .duty_cycle=0,
diff --git a/MAINTAINERS b/MAINTAINERS
index c584805952209..5342cf32d73ff 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17576,7 +17576,7 @@ F:	drivers/video/backlight/pwm_bl.c
 F:	include/dt-bindings/pwm/
 F:	include/linux/pwm.h
 F:	include/linux/pwm_backlight.h
-K:	pwm_(config|apply_might_sleep|ops)
+K:	pwm_(config|apply_might_sleep|apply_atomic|ops)
 
 PXA GPIO DRIVER
 M:	Robert Jarzmik <robert.jarzmik@free.fr>
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index c2d78136625d5..30c0623dbd5ba 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -433,24 +433,15 @@ static void pwm_apply_debug(struct pwm_device *pwm,
 }
 
 /**
- * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
+ * pwm_apply_unchecked() - atomically apply a new state to a PWM device
  * @pwm: PWM device
  * @state: new state to apply
  */
-int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
+static int pwm_apply_unchecked(struct pwm_device *pwm, const struct pwm_state *state)
 {
 	struct pwm_chip *chip;
 	int err;
 
-	/*
-	 * Some lowlevel driver's implementations of .apply() make use of
-	 * mutexes, also with some drivers only returning when the new
-	 * configuration is active calling pwm_apply_might_sleep() from atomic context
-	 * is a bad idea. So make it explicit that calling this function might
-	 * sleep.
-	 */
-	might_sleep();
-
 	if (!pwm || !state || !state->period ||
 	    state->duty_cycle > state->period)
 		return -EINVAL;
@@ -471,16 +462,66 @@ int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
 
 	pwm->state = *state;
 
+	return 0;
+}
+
+/**
+ * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
+ * Cannot be used in atomic context.
+ * @pwm: PWM device
+ * @state: new state to apply
+ */
+int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
+{
+	int err;
+
+	/*
+	 * Some lowlevel driver's implementations of .apply() make use of
+	 * mutexes, also with some drivers only returning when the new
+	 * configuration is active calling pwm_apply_might_sleep() from atomic context
+	 * is a bad idea. So make it explicit that calling this function might
+	 * sleep.
+	 */
+	might_sleep();
+
+	if (IS_ENABLED(CONFIG_PWM_DEBUG) && pwm->chip->atomic) {
+		/*
+		 * Catch any drivers that have been marked as atomic but
+		 * that will sleep anyway.
+		 */
+		non_block_start();
+		err = pwm_apply_unchecked(pwm, state);
+		non_block_end();
+	} else {
+		err = pwm_apply_unchecked(pwm, state);
+	}
+
 	/*
 	 * only do this after pwm->state was applied as some
 	 * implementations of .get_state depend on this
 	 */
-	pwm_apply_debug(pwm, state);
+	if (!err)
+		pwm_apply_debug(pwm, state);
 
-	return 0;
+	return err;
 }
 EXPORT_SYMBOL_GPL(pwm_apply_might_sleep);
 
+/**
+ * pwm_apply_atomic() - apply a new state to a PWM device from atomic context
+ * Not all PWM devices support this function, check with pwm_might_sleep().
+ * @pwm: PWM device
+ * @state: new state to apply
+ */
+int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state)
+{
+	WARN_ONCE(!pwm->chip->atomic,
+		  "sleeping PWM driver used in atomic context\n");
+
+	return pwm_apply_unchecked(pwm, state);
+}
+EXPORT_SYMBOL_GPL(pwm_apply_atomic);
+
 /**
  * pwm_capture() - capture and report a PWM signal
  * @pwm: PWM device
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index c9cb87b59ac80..495af3627939c 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -285,6 +285,7 @@ struct pwm_ops {
  * @npwm: number of PWMs controlled by this chip
  * @of_xlate: request a PWM device given a device tree PWM specifier
  * @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
+ * @atomic: can the driver's ->apply() be called in atomic context
  * @pwms: array of PWM devices allocated by the framework
  */
 struct pwm_chip {
@@ -297,6 +298,7 @@ struct pwm_chip {
 	struct pwm_device * (*of_xlate)(struct pwm_chip *chip,
 					const struct of_phandle_args *args);
 	unsigned int of_pwm_n_cells;
+	bool atomic;
 
 	/* only used internally by the PWM framework */
 	struct pwm_device *pwms;
@@ -305,6 +307,7 @@ struct pwm_chip {
 #if IS_ENABLED(CONFIG_PWM)
 /* PWM user APIs */
 int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state);
+int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state);
 int pwm_adjust_config(struct pwm_device *pwm);
 
 /**
@@ -375,6 +378,17 @@ static inline void pwm_disable(struct pwm_device *pwm)
 	pwm_apply_might_sleep(pwm, &state);
 }
 
+/**
+ * pwm_might_sleep() - is pwm_apply_atomic() supported?
+ * @pwm: PWM device
+ *
+ * Returns: false if pwm_apply_atomic() can be called from atomic context.
+ */
+static inline bool pwm_might_sleep(struct pwm_device *pwm)
+{
+	return !pwm->chip->atomic;
+}
+
 /* PWM provider APIs */
 int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
 		unsigned long timeout);
@@ -403,6 +417,11 @@ struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
 				       struct fwnode_handle *fwnode,
 				       const char *con_id);
 #else
+static inline bool pwm_might_sleep(struct pwm_device *pwm)
+{
+	return true;
+}
+
 static inline int pwm_apply_might_sleep(struct pwm_device *pwm,
 					const struct pwm_state *state)
 {
@@ -410,6 +429,12 @@ static inline int pwm_apply_might_sleep(struct pwm_device *pwm,
 	return -EOPNOTSUPP;
 }
 
+static inline int pwm_apply_atomic(struct pwm_device *pwm,
+				   const struct pwm_state *state)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline int pwm_adjust_config(struct pwm_device *pwm)
 {
 	return -EOPNOTSUPP;
-- 
2.43.0

[PATCH v8 5/6] pwm: bcm2835: Allow PWM driver to be used in atomic context

[Sean Young]

clk_get_rate() may do a mutex lock. Fetch the clock rate once, and prevent
rate changes using clk_rate_exclusive_get().

Signed-off-by: Sean Young <sean@mess.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/pwm/pwm-bcm2835.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
index ab30667f4f951..309d52ec43bbe 100644
--- a/drivers/pwm/pwm-bcm2835.c
+++ b/drivers/pwm/pwm-bcm2835.c
@@ -28,6 +28,7 @@ struct bcm2835_pwm {
 	struct device *dev;
 	void __iomem *base;
 	struct clk *clk;
+	unsigned long rate;
 };
 
 static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
@@ -63,17 +64,11 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 {
 
 	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
-	unsigned long rate = clk_get_rate(pc->clk);
 	unsigned long long period_cycles;
 	u64 max_period;
 
 	u32 val;
 
-	if (!rate) {
-		dev_err(pc->dev, "failed to get clock rate\n");
-		return -EINVAL;
-	}
-
 	/*
 	 * period_cycles must be a 32 bit value, so period * rate / NSEC_PER_SEC
 	 * must be <= U32_MAX. As U32_MAX * NSEC_PER_SEC < U64_MAX the
@@ -88,13 +83,13 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * <=> period < ((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate
 	 * <=> period <= ceil((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate) - 1
 	 */
-	max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, rate) - 1;
+	max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, pc->rate) - 1;
 
 	if (state->period > max_period)
 		return -EINVAL;
 
 	/* set period */
-	period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * rate, NSEC_PER_SEC);
+	period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * pc->rate, NSEC_PER_SEC);
 
 	/* don't accept a period that is too small */
 	if (period_cycles < PERIOD_MIN)
@@ -103,7 +98,7 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	writel(period_cycles, pc->base + PERIOD(pwm->hwpwm));
 
 	/* set duty cycle */
-	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * rate, NSEC_PER_SEC);
+	val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * pc->rate, NSEC_PER_SEC);
 	writel(val, pc->base + DUTY(pwm->hwpwm));
 
 	/* set polarity */
@@ -151,16 +146,31 @@ static int bcm2835_pwm_probe(struct platform_device *pdev)
 		return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk),
 				     "clock not found\n");
 
+	ret = clk_rate_exclusive_get(pc->clk);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret,
+				     "fail to get exclusive rate\n");
+
+	pc->rate = clk_get_rate(pc->clk);
+	if (!pc->rate) {
+		clk_rate_exclusive_put(pc->clk);
+		return dev_err_probe(&pdev->dev, -EINVAL,
+				     "failed to get clock rate\n");
+	}
+
 	pc->chip.dev = &pdev->dev;
 	pc->chip.ops = &bcm2835_pwm_ops;
+	pc->chip.atomic = true;
 	pc->chip.npwm = 2;
 
 	platform_set_drvdata(pdev, pc);
 
 	ret = devm_pwmchip_add(&pdev->dev, &pc->chip);
-	if (ret < 0)
+	if (ret < 0) {
+		clk_rate_exclusive_put(pc->clk);
 		return dev_err_probe(&pdev->dev, ret,
 				     "failed to add pwmchip\n");
+	}
 
 	return 0;
 }
@@ -169,6 +179,7 @@ static int bcm2835_pwm_suspend(struct device *dev)
 {
 	struct bcm2835_pwm *pc = dev_get_drvdata(dev);
 
+	clk_rate_exclusive_put(pc->clk);
 	clk_disable_unprepare(pc->clk);
 
 	return 0;
-- 
2.43.0

[PATCH v8 6/6] media: pwm-ir-tx: Trigger edges from hrtimer interrupt context

[Sean Young]

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 cf51e27609759..fe368aebbc139 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

Re: [PATCH v8 3/6] pwm: renesas: Remove unused include

[Uwe Kleine-König]

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On Tue, Dec 12, 2023 at 08:34:02AM +0000, Sean Young wrote:
> No mutex is used in this driver.
> 
> Signed-off-by: Sean Young <sean@mess.org>
> ---
>  drivers/pwm/pwm-renesas-tpu.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/pwm/pwm-renesas-tpu.c b/drivers/pwm/pwm-renesas-tpu.c
> index ce92db1f85113..28265fdfc92a9 100644
> --- a/drivers/pwm/pwm-renesas-tpu.c
> +++ b/drivers/pwm/pwm-renesas-tpu.c
> @@ -11,7 +11,6 @@
>  #include <linux/init.h>
>  #include <linux/ioport.h>
>  #include <linux/module.h>
> -#include <linux/mutex.h>
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v8 2/6] pwm: Replace ENOTSUPP with EOPNOTSUPP

[Uwe Kleine-König]

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On Tue, Dec 12, 2023 at 08:34:01AM +0000, Sean Young wrote:
> ENOTSUPP is not a standard error code and should be avoided.

I'd write:

	According to Documentation/dev-tools/checkpatch.rst ENOTSUPP is
	not recommended and EOPNOTSUPP should be used instead.

to give the sentence a bit of authority.

Other than that I'm fine with the change.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v8 1/6] pwm: Rename pwm_apply_state() to pwm_apply_might_sleep()

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 1434 bytes --]

On Tue, Dec 12, 2023 at 08:34:00AM +0000, Sean Young wrote:
> In order to introduce a pwm api which can be used from atomic context,
> we will need two functions for applying pwm changes:
> 
> 	int pwm_apply_might_sleep(struct pwm *, struct pwm_state *);
> 	int pwm_apply_atomic(struct pwm *, struct pwm_state *);
> 
> This commit just deals with renaming pwm_apply_state(), a following
> commit will introduce the pwm_apply_atomic() function.
> 
> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> # for input
> Acked-by: Hans de Goede <hdegoede@redhat.com>
> Acked-by: Jani Nikula <jani.nikula@intel.com>
> Acked-by: Lee Jones <lee@kernel.org>
> Signed-off-by: Sean Young <sean@mess.org>

Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Several affected maintainers already acked, so I guess it's fine to take
this via the pwm tree. An Ack from the remaining maintainers would be
very welcome, an alternative would be to split the patch.

Missing Acks so far:

 - Jean Delvare / Guenter Roeck for drivers/hwmon/pwm-fan.c
 - Javier Martinez Canillas for drivers/gpu/drm/solomon/ssd130x.c
 - Liam Girdwood / Mark Brown for drivers/regulator/pwm-regulator.c
 - Helge Deller for drivers/video/fbdev/ssd1307fb.c

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v8 4/6] pwm: Make it possible to apply PWM changes in atomic context

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 1774 bytes --]

Hello Sean,

On Tue, Dec 12, 2023 at 08:34:03AM +0000, Sean Young wrote:
> +/**
> + * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
> + * Cannot be used in atomic context.
> + * @pwm: PWM device
> + * @state: new state to apply
> + */
> +int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
> +{
> +	int err;
> +
> +	/*
> +	 * Some lowlevel driver's implementations of .apply() make use of
> +	 * mutexes, also with some drivers only returning when the new
> +	 * configuration is active calling pwm_apply_might_sleep() from atomic context
> +	 * is a bad idea. So make it explicit that calling this function might
> +	 * sleep.
> +	 */
> +	might_sleep();
> +
> +	if (IS_ENABLED(CONFIG_PWM_DEBUG) && pwm->chip->atomic) {
> +		/*
> +		 * Catch any drivers that have been marked as atomic but
> +		 * that will sleep anyway.
> +		 */
> +		non_block_start();
> +		err = pwm_apply_unchecked(pwm, state);
> +		non_block_end();
> +	} else {
> +		err = pwm_apply_unchecked(pwm, state);
> +	}
> +
>  	/*
>  	 * only do this after pwm->state was applied as some
>  	 * implementations of .get_state depend on this
>  	 */
> -	pwm_apply_debug(pwm, state);
> +	if (!err)
> +		pwm_apply_debug(pwm, state);

It's easier to keep that in pwm_apply_unchecked(), isn't it? Then
pwm_apply_atomic() also benefits from the checks.

I'm not so happy with the function name of pwm_apply_unchecked(), but I
don't have a good suggestion either. Probably I'd have chosen
__pam_apply(), but that's probably subjective.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v8 5/6] pwm: bcm2835: Allow PWM driver to be used in atomic context

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 562 bytes --]

On Tue, Dec 12, 2023 at 08:34:04AM +0000, Sean Young wrote:
> clk_get_rate() may do a mutex lock. Fetch the clock rate once, and prevent
> rate changes using clk_rate_exclusive_get().
> 
> Signed-off-by: Sean Young <sean@mess.org>
> Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>

Looks good,

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v8 1/6] pwm: Rename pwm_apply_state() to pwm_apply_might_sleep()

[Guenter Roeck]

On 12/12/23 03:41, Uwe Kleine-König wrote:
> On Tue, Dec 12, 2023 at 08:34:00AM +0000, Sean Young wrote:
>> In order to introduce a pwm api which can be used from atomic context,
>> we will need two functions for applying pwm changes:
>>
>> 	int pwm_apply_might_sleep(struct pwm *, struct pwm_state *);
>> 	int pwm_apply_atomic(struct pwm *, struct pwm_state *);
>>
>> This commit just deals with renaming pwm_apply_state(), a following
>> commit will introduce the pwm_apply_atomic() function.
>>
>> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> # for input
>> Acked-by: Hans de Goede <hdegoede@redhat.com>
>> Acked-by: Jani Nikula <jani.nikula@intel.com>
>> Acked-by: Lee Jones <lee@kernel.org>
>> Signed-off-by: Sean Young <sean@mess.org>
> 
> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> 
> Several affected maintainers already acked, so I guess it's fine to take
> this via the pwm tree. An Ack from the remaining maintainers would be
> very welcome, an alternative would be to split the patch.
> 
> Missing Acks so far:
> 
>   - Jean Delvare / Guenter Roeck for drivers/hwmon/pwm-fan.c
>   - Javier Martinez Canillas for drivers/gpu/drm/solomon/ssd130x.c
>   - Liam Girdwood / Mark Brown for drivers/regulator/pwm-regulator.c
>   - Helge Deller for drivers/video/fbdev/ssd1307fb.c
> 
> Best regards
> Uwe
> 


Personally I find the change unnecessary and pointless, which is why I
didn't ack it. Even if function names were deemed important enough, keeping
pwm_apply_state() for the time being and just adding pwm_apply_might_sleep()
as duplicate would have done it, all the changes could have gone in long
ago, and per-subsystem cleanup could have been orthogonal.

I refrained from commenting because it might be considered bike shedding,
but I don't want to ack something I deem unnecessary and pointless without
comment. But then don't want to keep arguing either, so

Acked-by: Guenter Roeck <linux@roeck-us.net>

Guenter

Re: [PATCH v8 1/6] pwm: Rename pwm_apply_state() to pwm_apply_might_sleep()

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 1407 bytes --]

On Tue, Dec 12, 2023 at 07:22:18AM -0800, Guenter Roeck wrote:
> On 12/12/23 03:41, Uwe Kleine-König wrote:

> > Several affected maintainers already acked, so I guess it's fine to take
> > this via the pwm tree. An Ack from the remaining maintainers would be
> > very welcome, an alternative would be to split the patch.

> > Missing Acks so far:

> >   - Jean Delvare / Guenter Roeck for drivers/hwmon/pwm-fan.c
> >   - Javier Martinez Canillas for drivers/gpu/drm/solomon/ssd130x.c
> >   - Liam Girdwood / Mark Brown for drivers/regulator/pwm-regulator.c
> >   - Helge Deller for drivers/video/fbdev/ssd1307fb.c

> Personally I find the change unnecessary and pointless, which is why I
> didn't ack it. Even if function names were deemed important enough, keeping
> pwm_apply_state() for the time being and just adding pwm_apply_might_sleep()
> as duplicate would have done it, all the changes could have gone in long
> ago, and per-subsystem cleanup could have been orthogonal.

> I refrained from commenting because it might be considered bike shedding,
> but I don't want to ack something I deem unnecessary and pointless without
> comment. But then don't want to keep arguing either, so

I haven't been reading this series because I couldn't tell why I was
copied on it, it's only chance that made me open Guenter's mail here...

Acked-by: Mark Brown <broonie@kernel.org>

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Re: [PATCH v8 5/6] pwm: bcm2835: Allow PWM driver to be used in atomic context

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 580 bytes --]

Hello Sean,

On Tue, Dec 12, 2023 at 08:34:04AM +0000, Sean Young wrote:
> @@ -169,6 +179,7 @@ static int bcm2835_pwm_suspend(struct device *dev)
>  {
>  	struct bcm2835_pwm *pc = dev_get_drvdata(dev);
>  
> +	clk_rate_exclusive_put(pc->clk);
>  	clk_disable_unprepare(pc->clk);

I thought this was the remove function, but that's suspend. Adding
clk_rate_exclusive_put() there is wrong.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v8 5/6] pwm: bcm2835: Allow PWM driver to be used in atomic context

[Florian Fainelli]

[-- Attachment #1: Type: text/plain, Size: 519 bytes --]



On 12/12/2023 8:08 AM, Uwe Kleine-König wrote:
> Hello Sean,
> 
> On Tue, Dec 12, 2023 at 08:34:04AM +0000, Sean Young wrote:
>> @@ -169,6 +179,7 @@ static int bcm2835_pwm_suspend(struct device *dev)
>>   {
>>   	struct bcm2835_pwm *pc = dev_get_drvdata(dev);
>>   
>> +	clk_rate_exclusive_put(pc->clk);
>>   	clk_disable_unprepare(pc->clk);
> 
> I thought this was the remove function, but that's suspend. Adding
> clk_rate_exclusive_put() there is wrong.

Oh yes I missed that somehow, good catch Uwe!
-- 
Florian

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Re: [PATCH v8 5/6] pwm: bcm2835: Allow PWM driver to be used in atomic context

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 822 bytes --]

Hello Sean,

On Tue, Dec 12, 2023 at 05:08:38PM +0100, Uwe Kleine-König wrote:
> On Tue, Dec 12, 2023 at 08:34:04AM +0000, Sean Young wrote:
> > @@ -169,6 +179,7 @@ static int bcm2835_pwm_suspend(struct device *dev)
> >  {
> >  	struct bcm2835_pwm *pc = dev_get_drvdata(dev);
> >  
> > +	clk_rate_exclusive_put(pc->clk);
> >  	clk_disable_unprepare(pc->clk);
> 
> I thought this was the remove function, but that's suspend. Adding
> clk_rate_exclusive_put() there is wrong.

https://lore.kernel.org/linux-clk/744a6371f94fe96f527eea6e52a600914e6fb6b5.1702403904.git.u.kleine-koenig@pengutronix.de/
might be useful to fix this.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v8 5/6] pwm: bcm2835: Allow PWM driver to be used in atomic context

[Sean Young]

On Tue, Dec 12, 2023 at 07:14:44PM +0100, Uwe Kleine-König wrote:
> Hello Sean,
> 
> On Tue, Dec 12, 2023 at 05:08:38PM +0100, Uwe Kleine-König wrote:
> > On Tue, Dec 12, 2023 at 08:34:04AM +0000, Sean Young wrote:
> > > @@ -169,6 +179,7 @@ static int bcm2835_pwm_suspend(struct device *dev)
> > >  {
> > >  	struct bcm2835_pwm *pc = dev_get_drvdata(dev);
> > >  
> > > +	clk_rate_exclusive_put(pc->clk);
> > >  	clk_disable_unprepare(pc->clk);
> > 
> > I thought this was the remove function, but that's suspend. Adding
> > clk_rate_exclusive_put() there is wrong.
> 
> https://lore.kernel.org/linux-clk/744a6371f94fe96f527eea6e52a600914e6fb6b5.1702403904.git.u.kleine-koenig@pengutronix.de/
> might be useful to fix this.

That does look useful, I suppose I can only use it once it's merged in
pwm-next though. Leaving out for v9.

Thanks,
Sean

Re: [PATCH v8 5/6] pwm: bcm2835: Allow PWM driver to be used in atomic context

[Sean Young]

On Tue, Dec 12, 2023 at 05:08:38PM +0100, Uwe Kleine-König wrote:
> Hello Sean,
> 
> On Tue, Dec 12, 2023 at 08:34:04AM +0000, Sean Young wrote:
> > @@ -169,6 +179,7 @@ static int bcm2835_pwm_suspend(struct device *dev)
> >  {
> >  	struct bcm2835_pwm *pc = dev_get_drvdata(dev);
> >  
> > +	clk_rate_exclusive_put(pc->clk);
> >  	clk_disable_unprepare(pc->clk);
> 
> I thought this was the remove function, but that's suspend. Adding
> clk_rate_exclusive_put() there is wrong.

Nice catch - fixed in v9.


Sean

Re: [PATCH v8 4/6] pwm: Make it possible to apply PWM changes in atomic context

[Sean Young]

Hello Uwe,

On Tue, Dec 12, 2023 at 12:48:12PM +0100, Uwe Kleine-König wrote:
> On Tue, Dec 12, 2023 at 08:34:03AM +0000, Sean Young wrote:
> > +/**
> > + * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
> > + * Cannot be used in atomic context.
> > + * @pwm: PWM device
> > + * @state: new state to apply
> > + */
> > +int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
> > +{
> > +	int err;
> > +
> > +	/*
> > +	 * Some lowlevel driver's implementations of .apply() make use of
> > +	 * mutexes, also with some drivers only returning when the new
> > +	 * configuration is active calling pwm_apply_might_sleep() from atomic context
> > +	 * is a bad idea. So make it explicit that calling this function might
> > +	 * sleep.
> > +	 */
> > +	might_sleep();
> > +
> > +	if (IS_ENABLED(CONFIG_PWM_DEBUG) && pwm->chip->atomic) {
> > +		/*
> > +		 * Catch any drivers that have been marked as atomic but
> > +		 * that will sleep anyway.
> > +		 */
> > +		non_block_start();
> > +		err = pwm_apply_unchecked(pwm, state);
> > +		non_block_end();
> > +	} else {
> > +		err = pwm_apply_unchecked(pwm, state);
> > +	}
> > +
> >  	/*
> >  	 * only do this after pwm->state was applied as some
> >  	 * implementations of .get_state depend on this
> >  	 */
> > -	pwm_apply_debug(pwm, state);
> > +	if (!err)
> > +		pwm_apply_debug(pwm, state);
> 
> It's easier to keep that in pwm_apply_unchecked(), isn't it? Then
> pwm_apply_atomic() also benefits from the checks.

Good point.

> I'm not so happy with the function name of pwm_apply_unchecked(), but I
> don't have a good suggestion either. Probably I'd have chosen
> __pam_apply(), but that's probably subjective.

That is more consistent, fixed in v9.


Sean