linux-kernel - [PATCH v7 2/4] pwm: Let pwm_set_waveform_might_sleep() return 0 instead of 1 after rounding up

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Message-ID:  <528cc3bbd9e35dea8646b1bcc0fbfe6c498bb4ed.1746010245.git.u.kleine-koenig@baylibre.com>
Date: Wed, 30 Apr 2025 13:55:59 +0200
From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
To: linux-pwm@...r.kernel.org
Cc: David Lechner <dlechner@...libre.com>,
	Kent Gibson <warthog618@...il.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v7 2/4] pwm: Let pwm_set_waveform_might_sleep() return 0 instead of 1 after rounding up

While telling the caller of pwm_set_waveform_might_sleep() if the
request was completed by rounding down only or (some) rounding up gives
additional information, it makes usage this function needlessly hard and
the additional information is not used. A prove for that is that
currently both users of this function just pass the returned value up to
their caller even though a positive value isn't intended there.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...libre.com>
---
 drivers/pwm/core.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 28cb6ab0f62d..5cf64b3a4cdf 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -411,9 +411,8 @@ static int __pwm_set_waveform(struct pwm_device *pwm,
  * possible/needed. In the above example requesting .period_length_ns = 94 and
  * @exact = true, you get the hardware configured with period = 93.5 ns.
  *
- * Returns: 0 on success, 1 if was rounded up (if !@...ct), -EDOM if setting
- * failed due to the exact waveform not being possible (if @exact), or a
- * different negative errno on failure.
+ * Returns: 0 on success, -EDOM if setting failed due to the exact waveform not
+ * being possible (if @exact), or a different negative errno on failure.
  * Context: May sleep.
  */
 int pwm_set_waveform_might_sleep(struct pwm_device *pwm,
@@ -442,14 +441,17 @@ int pwm_set_waveform_might_sleep(struct pwm_device *pwm,
 	}
 
 	/*
-	 * map err == 1 to -EDOM for exact requests. Also make sure that -EDOM is
-	 * only returned in exactly that case. Note that __pwm_set_waveform()
-	 * should never return -EDOM which justifies the unlikely().
+	 * map err == 1 to -EDOM for exact requests and 0 for !exact ones. Also
+	 * make sure that -EDOM is only returned in exactly that case. Note that
+	 * __pwm_set_waveform() should never return -EDOM which justifies the
+	 * unlikely().
 	 */
 	if (unlikely(err == -EDOM))
 		err = -EINVAL;
 	else if (exact && err == 1)
 		err = -EDOM;
+	else if (err == 1)
+		err = 0;
 
 	return err;
 }
-- 
2.47.2