linux-kernel - [PATCH v6 1/2] pwm: Better document return value of pwm_round_waveform_might

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID:  <db84abf1e82e4498fc0e7c318d2673771d0039fe.1744120697.git.ukleinek@kernel.org>
Date: Tue,  8 Apr 2025 16:23:54 +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 v6 1/2] pwm: Better document return value of pwm_round_waveform_might_sleep()

Better explain how pwm_round_waveform_might_sleep() (and so the
respective lowlevel driver callback) is supposed to round and the
meaning of the return value.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...libre.com>
---
 drivers/pwm/core.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 59cc8792e312..cec325bdffa5 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -229,8 +229,12 @@ static int __pwm_write_waveform(struct pwm_chip *chip, struct pwm_device *pwm, c
  * these two calls and the waveform determined by
  * pwm_round_waveform_might_sleep() cannot be implemented any more.
  *
- * Returns 0 on success, 1 if there is no valid hardware configuration matching
- * the input waveform under the PWM rounding rules or a negative errno.
+ * Usually all values passed in *wf are rounded down to the nearest possible
+ * value (in the order period_length_ns, duty_length_ns and then
+ * duty_offset_ns). Only if this isn't possible, a value might grow.
+ *
+ * Returns 0 on success, 1 if at least one value had to be rounded up or a
+ * negative errno.
  */
 int pwm_round_waveform_might_sleep(struct pwm_device *pwm, struct pwm_waveform *wf)
 {
-- 
2.47.2