linux-kernel - [PATCH v4 1/8] pwm: Declare waveform stubs for when PWM is not reachable

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Message-ID: <129ff5c5b7f7be4f4f3f9cf8aa3e1957d713acb7.1759929814.git.marcelo.schmitt@analog.com>
Date: Wed, 8 Oct 2025 10:49:44 -0300
From: Marcelo Schmitt <marcelo.schmitt@...log.com>
To: <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <linux-pwm@...r.kernel.org>,
        <linux-spi@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <jic23@...nel.org>, <ukleinek@...nel.org>, <michael.hennerich@...log.com>,
        <nuno.sa@...log.com>, <eblanc@...libre.com>, <dlechner@...libre.com>,
        <andy@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
        <conor+dt@...nel.org>, <corbet@....net>, <marcelo.schmitt1@...il.com>,
        "kernel test robot" <lkp@...el.com>
Subject: [PATCH v4 1/8] pwm: Declare waveform stubs for when PWM is not reachable

Previously, the PWM waveform consumer API would not be declared if
CONFIG_PWM was not reachable. That caused kernel builds to fail if a
consumer driver was enabled but PWM disabled. Add stubs for PWM waveform
functions so client drivers that use, but don't depend on PWM, can build if
PWM is disabled.

Fixes: 6c5126c6406d ("pwm: Provide new consumer API functions for waveforms")
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202509272028.0zLNiR5w-lkp@intel.com/
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@...log.com>
---
I've included this patch in this series because it should save us from being
notified by 0-day about the build failure this patch fixes. From contributor's
perspective, it's easier to have this patch together with the rest of ad4030
series. Though, no objection if kernel maintainers decide to pick it [1] through
the PWM tree.

[1]: https://lore.kernel.org/linux-pwm/1ac0fc529e02744aacfcb9140ed597ff60886f39.1759873890.git.marcelo.schmitt@analog.com/

Thanks,
Marcelo

 include/linux/pwm.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 8cafc483db53..e79545c0cb89 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -501,6 +501,25 @@ struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
 				       struct fwnode_handle *fwnode,
 				       const char *con_id);
 #else
+static inline int pwm_round_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform *wf)
+{
+	might_sleep();
+	return -EOPNOTSUPP;
+}
+
+static inline int pwm_get_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform *wf)
+{
+	might_sleep();
+	return -EOPNOTSUPP;
+}
+
+static inline int pwm_set_waveform_might_sleep(struct pwm_device *pwm,
+					       const struct pwm_waveform *wf, bool exact)
+{
+	might_sleep();
+	return -EOPNOTSUPP;
+}
+
 static inline bool pwm_might_sleep(struct pwm_device *pwm)
 {
 	return true;
-- 
2.39.2