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8c405cdccc
The patches were generated from the RPi repo with the following command: git format-patch v6.6.34..rpi-6.1.y Some patches needed rebasing and, as usual, the applied and reverted, wireless drivers, Github workflows, READMEs and defconfigs patches were removed. Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
217 lines
6.9 KiB
Diff
217 lines
6.9 KiB
Diff
From 8b5840b077e3b51ccdf840010600aec211a8990b Mon Sep 17 00:00:00 2001
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From: Sean Young <sean@mess.org>
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Date: Tue, 19 Dec 2023 16:30:27 +0000
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Subject: [PATCH 1128/1135] pwm: Make it possible to apply PWM changes in
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atomic context
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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commit 7170d3beafc2373dd76b6b5d6e617d89e4e42b8b upstream.
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Some PWM devices require sleeping, for example if the pwm device is
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connected over I2C. However, many PWM devices could be used from atomic
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context, e.g. memory mapped PWM. This is useful for, for example, the
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pwm-ir-tx driver which requires precise timing. Sleeping causes havoc
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with the generated IR signal.
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Since not all PWM devices can support atomic context, we also add a
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pwm_might_sleep() function to check if is not supported.
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Signed-off-by: Sean Young <sean@mess.org>
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Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
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Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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---
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Documentation/driver-api/pwm.rst | 9 +++++
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MAINTAINERS | 2 +-
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drivers/pwm/core.c | 62 ++++++++++++++++++++++++++------
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include/linux/pwm.h | 25 +++++++++++++
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4 files changed, 86 insertions(+), 12 deletions(-)
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--- a/Documentation/driver-api/pwm.rst
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+++ b/Documentation/driver-api/pwm.rst
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@@ -46,6 +46,15 @@ After being requested, a PWM has to be c
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This API controls both the PWM period/duty_cycle config and the
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enable/disable state.
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+PWM devices can be used from atomic context, if the PWM does not sleep. You
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+can check if this the case with::
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+
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+ bool pwm_might_sleep(struct pwm_device *pwm);
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+
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+If false, the PWM can also be configured from atomic context with::
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+
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+ int pwm_apply_atomic(struct pwm_device *pwm, struct pwm_state *state);
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+
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As a consumer, don't rely on the output's state for a disabled PWM. If it's
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easily possible, drivers are supposed to emit the inactive state, but some
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drivers cannot. If you rely on getting the inactive state, use .duty_cycle=0,
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--- a/MAINTAINERS
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+++ b/MAINTAINERS
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@@ -17437,7 +17437,7 @@ F: drivers/video/backlight/pwm_bl.c
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F: include/dt-bindings/pwm/
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F: include/linux/pwm.h
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F: include/linux/pwm_backlight.h
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-K: pwm_(config|apply_might_sleep|ops)
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+K: pwm_(config|apply_might_sleep|apply_atomic|ops)
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PXA GPIO DRIVER
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M: Robert Jarzmik <robert.jarzmik@free.fr>
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--- a/drivers/pwm/core.c
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+++ b/drivers/pwm/core.c
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@@ -489,24 +489,15 @@ static void pwm_apply_debug(struct pwm_d
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}
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/**
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- * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
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+ * __pwm_apply() - atomically apply a new state to a PWM device
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* @pwm: PWM device
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* @state: new state to apply
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*/
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-int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
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+static int __pwm_apply(struct pwm_device *pwm, const struct pwm_state *state)
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{
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struct pwm_chip *chip;
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int err;
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- /*
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- * Some lowlevel driver's implementations of .apply() make use of
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- * mutexes, also with some drivers only returning when the new
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- * configuration is active calling pwm_apply_might_sleep() from atomic context
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- * is a bad idea. So make it explicit that calling this function might
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- * sleep.
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- */
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- might_sleep();
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-
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if (!pwm || !state || !state->period ||
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state->duty_cycle > state->period)
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return -EINVAL;
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@@ -535,9 +526,58 @@ int pwm_apply_might_sleep(struct pwm_dev
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return 0;
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}
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+
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+/**
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+ * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
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+ * Cannot be used in atomic context.
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+ * @pwm: PWM device
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+ * @state: new state to apply
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+ */
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+int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
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+{
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+ int err;
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+
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+ /*
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+ * Some lowlevel driver's implementations of .apply() make use of
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+ * mutexes, also with some drivers only returning when the new
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+ * configuration is active calling pwm_apply_might_sleep() from atomic context
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+ * is a bad idea. So make it explicit that calling this function might
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+ * sleep.
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+ */
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+ might_sleep();
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+
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+ if (IS_ENABLED(CONFIG_PWM_DEBUG) && pwm->chip->atomic) {
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+ /*
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+ * Catch any drivers that have been marked as atomic but
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+ * that will sleep anyway.
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+ */
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+ non_block_start();
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+ err = __pwm_apply(pwm, state);
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+ non_block_end();
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+ } else {
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+ err = __pwm_apply(pwm, state);
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+ }
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+
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+ return err;
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+}
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EXPORT_SYMBOL_GPL(pwm_apply_might_sleep);
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/**
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+ * pwm_apply_atomic() - apply a new state to a PWM device from atomic context
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+ * Not all PWM devices support this function, check with pwm_might_sleep().
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+ * @pwm: PWM device
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+ * @state: new state to apply
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+ */
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+int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state)
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+{
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+ WARN_ONCE(!pwm->chip->atomic,
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+ "sleeping PWM driver used in atomic context\n");
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+
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+ return __pwm_apply(pwm, state);
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+}
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+EXPORT_SYMBOL_GPL(pwm_apply_atomic);
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+
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+/**
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* pwm_capture() - capture and report a PWM signal
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* @pwm: PWM device
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* @result: structure to fill with capture result
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--- a/include/linux/pwm.h
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+++ b/include/linux/pwm.h
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@@ -289,6 +289,7 @@ struct pwm_ops {
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* @npwm: number of PWMs controlled by this chip
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* @of_xlate: request a PWM device given a device tree PWM specifier
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* @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
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+ * @atomic: can the driver's ->apply() be called in atomic context
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* @list: list node for internal use
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* @pwms: array of PWM devices allocated by the framework
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*/
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@@ -301,6 +302,7 @@ struct pwm_chip {
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struct pwm_device * (*of_xlate)(struct pwm_chip *chip,
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const struct of_phandle_args *args);
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unsigned int of_pwm_n_cells;
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+ bool atomic;
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/* only used internally by the PWM framework */
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struct list_head list;
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@@ -310,6 +312,7 @@ struct pwm_chip {
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#if IS_ENABLED(CONFIG_PWM)
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/* PWM user APIs */
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int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state);
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+int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state);
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int pwm_adjust_config(struct pwm_device *pwm);
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/**
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@@ -380,6 +383,17 @@ static inline void pwm_disable(struct pw
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pwm_apply_might_sleep(pwm, &state);
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}
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+/**
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+ * pwm_might_sleep() - is pwm_apply_atomic() supported?
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+ * @pwm: PWM device
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+ *
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+ * Returns: false if pwm_apply_atomic() can be called from atomic context.
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+ */
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+static inline bool pwm_might_sleep(struct pwm_device *pwm)
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+{
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+ return !pwm->chip->atomic;
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+}
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+
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/* PWM provider APIs */
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int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
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unsigned long timeout);
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@@ -408,6 +422,11 @@ struct pwm_device *devm_fwnode_pwm_get(s
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struct fwnode_handle *fwnode,
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const char *con_id);
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#else
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+static inline bool pwm_might_sleep(struct pwm_device *pwm)
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+{
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+ return true;
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+}
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+
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static inline int pwm_apply_might_sleep(struct pwm_device *pwm,
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const struct pwm_state *state)
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{
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@@ -415,6 +434,12 @@ static inline int pwm_apply_might_sleep(
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return -EOPNOTSUPP;
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}
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+static inline int pwm_apply_atomic(struct pwm_device *pwm,
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+ const struct pwm_state *state)
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+{
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+ return -EOPNOTSUPP;
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+}
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+
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static inline int pwm_adjust_config(struct pwm_device *pwm)
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{
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return -EOPNOTSUPP;
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