linux-kernel - [PATCH v4 2/4] pwm: pca9685: Set full OFF bits in probe

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Date:   Mon,  7 Dec 2020 20:36:28 +0100
From:   Clemens Gruber <clemens.gruber@...ruber.com>
To:     linux-pwm@...r.kernel.org
Cc:     Thierry Reding <thierry.reding@...il.com>,
        u.kleine-koenig@...gutronix.de, Lee Jones <lee.jones@...aro.org>,
        linux-kernel@...r.kernel.org,
        Sven Van Asbroeck <TheSven73@...il.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        David Jander <david@...tonic.nl>,
        Clemens Gruber <clemens.gruber@...ruber.com>
Subject: [PATCH v4 2/4] pwm: pca9685: Set full OFF bits in probe

The full OFF bits are set by default in the PCA9685 LEDn_OFF_H
registers at POR. LEDn_ON_L/H and LEDn_OFF_L default to 0.

The datasheet states that LEDn_OFF and LEDn_ON should never be both set
to the same values.

This patch removes the clearing of the full OFF bit in the probe
function. We still clear the rest of the OFF regs but now we set the
full OFF bit to avoid having both OFF and ON registers set to 0 and
start up in a safe default state.

Signed-off-by: Clemens Gruber <clemens.gruber@...ruber.com>
---
Changes since v1:
- Rebased

 drivers/pwm/pwm-pca9685.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index 0425e0bcb81e..fdce5fb9f41e 100644
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -486,9 +486,9 @@ static int pca9685_pwm_probe(struct i2c_client *client,
 	reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
 	regmap_write(pca->regmap, PCA9685_MODE1, reg);
 
-	/* Clear all "full off" bits */
+	/* Reset OFF registers to HW default (only full OFF bit is set) */
 	regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, 0);
-	regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, 0);
+	regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, LED_FULL);
 
 	pca->chip.ops = &pca9685_pwm_ops;
 	/* Add an extra channel for ALL_LED */
-- 
2.29.2