Re: [PATCH 2/2] hwmon: (pwm-fan): support target-pwm property to set default PWM value

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On 4/24/24 02:04, Peter Korsgaard wrote:
For some use cases defaulting the PWM to full fan speed is not ideal
(noise, power consumption, ..), so support an optional target-pwm
property (0..255) to override the default PWM value.

Signed-off-by: Peter Korsgaard <peter@xxxxxxxxxxxxx>
---
  drivers/hwmon/pwm-fan.c | 11 +++++++++--
  1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index b67bc9e833c0..ebdefbd5789c 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -482,6 +482,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
  	const struct hwmon_channel_info **channels;
  	u32 *fan_channel_config;
  	int channel_count = 1;	/* We always have a PWM channel. */
+	u32 target_pwm = MAX_PWM;
  	int i;
ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
@@ -527,11 +528,17 @@ static int pwm_fan_probe(struct platform_device *pdev)
ctx->enable_mode = pwm_disable_reg_enable; + of_property_read_u32(dev->of_node, "target-pwm", &target_pwm);
+	if (target_pwm > (u32)MAX_PWM) {
+		dev_err(dev, "Invalid target-pwm: %u > %d\n", target_pwm, MAX_PWM);
+		return -EINVAL;
+	}
+
  	/*
-	 * Set duty cycle to maximum allowed and enable PWM output as well as
+	 * Set duty cycle to target and enable PWM output as well as
  	 * the regulator. In case of error nothing is changed
  	 */
-	ret = set_pwm(ctx, MAX_PWM);
+	ret = set_pwm(ctx, target_pwm);
  	if (ret) {
  		dev_err(dev, "Failed to configure PWM: %d\n", ret);
  		return ret;

A much better name would be default-pwm for the property name.
target-pwm is misleading and doesn't really make sense because
there is no "target", just a value that is being set.

Guenter





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