Re: [PATCH v2 1/8] leds: Add support for AXP20X CHGLED

From: Stefan Mavrodiev
Date: Tue Feb 19 2019 - 02:42:49 EST

On 2/15/19 8:32 PM, Pavel Machek wrote:

On Fri, Feb 15, 2019 at 01:50:06PM +0200, Stefan Mavrodiev wrote:
+static ssize_t control_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t size)
+ struct led_classdev *cdev = dev_get_drvdata(dev);
+ struct axp20x_led *priv = to_axp20x_led(cdev);
+ unsigned long val;
+ int ret;
+ ret = kstrtoul(buf, 0, &val);
+ if (ret)
+ return ret;
+ /**
+ * Supported values are:
+ * - 0 : Manual control
+ * - 1 : Charger control
+ */
+static struct attribute *axp20x_led_attrs[] = {
+ &dev_attr_control.attr,
+ &dev_attr_mode.attr,
I can't really say whether adding sysfs handles for this is the right
thing to do, but if it is you should document the interface.
It is not. See "Add Intel Cherry Trail Whiskey Cove PMIC LEDs" thread
in the last few days.

What I understood is that there will be changes in the LED core, exporting
a new sysfs entry "hw_control". Then I should set HW_CONTROL flag for the
device and add hw_control_get/set callback functions. And this can happen
when the LED core is updated. Right?

However I didn't understand how (in my case) hardware controlled pattern
will be selected?

Best regards,
Stefan Mavrodiev

+ if (!of_property_read_u8(np, "x-powers,charger-mode", &value)) {
+ priv->ctrl = AXP20X_CHGLED_CTRL_CHARGER;
+ priv->mode = (value < 2) ? value : 0;
+ } else {
+ priv->ctrl = AXP20X_CHGLED_CTRL_MANUAL;
+ }
I'm not sure we want to make this a property of the device
tree. Changing the device tree isn't an option for some users, so we
need to make sure we can change it even if we can't change the device
We want this to be configurable at run time. It can get default from
the device tree.

If we go for the "hardware" trigger, you'll get it for free.

Best regards,