From: Sven Van Asbroeck <thesven73@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: "Matthias Schiffer" <matthias.schiffer@ew.tq-group.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Clemens Gruber" <clemens.gruber@pqgruber.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v1] pwm: pca9685: re-enable active pwm channels on pwm period change
Date: Fri, 3 Apr 2020 19:53:24 -0400 [thread overview]
Message-ID: <20200403235324.27437-1-TheSven73@gmail.com> (raw)
In order to change the pwm period, this chip must be put in sleep
mode. However, when coming out of sleep mode, the pwm channel
state is not completely restored: all pwm channels are off by
default.
This results in a bug in this driver: when the pwm period is changed
on a pwm channel, all other pwm channels will be deactivated.
Fix by clearing the RESTART bit when coming out of sleep mode - this
will restore all pwm channels to their pre-sleep on/off state.
Reported-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Cc: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Clemens Gruber <clemens.gruber@pqgruber.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: linux-pwm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/lkml/32ec35c2b3da119dd2c7bc09742796a0d8a9607e.camel@ew.tq-group.com/
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
---
I no longer have access to pca9685 hardware, so I'm unable to test:
- if this is indeed a bug
- if this patch fixes it
Made against:
Tree-repo: git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm.git
Tree-branch: for-next
Tree-git-id: 9cc5f232a4b6a0ef6e9b57876d61b88f61bdd7c2
drivers/pwm/pwm-pca9685.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index 76cd22bd6614..0a16f0122e0e 100644
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -59,6 +59,7 @@
#define LED_FULL (1 << 4)
#define MODE1_SLEEP (1 << 4)
+#define MODE1_RESTART (1 << 7)
#define MODE2_INVRT (1 << 4)
#define MODE2_OUTDRV (1 << 2)
@@ -271,6 +272,15 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
/* Wake the chip up */
pca9685_set_sleep_mode(pca, false);
+ /* If any pwm channels were active when the chip was put
+ * in sleep mode, re-activate them.
+ */
+ if (!regmap_read(pca->regmap, PCA9685_MODE1, ®) &&
+ reg & MODE1_RESTART)
+ regmap_update_bits(pca->regmap, PCA9685_MODE1,
+ MODE1_RESTART,
+ MODE1_RESTART);
+
pca->period_ns = period_ns;
} else {
dev_err(chip->dev,
--
2.17.1
next reply other threads:[~2020-04-03 23:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-03 23:53 Sven Van Asbroeck [this message]
2020-04-04 17:58 ` [PATCH v1] pwm: pca9685: re-enable active pwm channels on pwm period change Clemens Gruber
2020-04-04 19:21 ` Sven Van Asbroeck
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