On Tue, Oct 01, 2024 at 04:45:23AM +0200, Marek Vasut wrote:
> The trigger_data->hw_control indicates whether the LED is controlled by HW
> offload, i.e. the PHY. The trigger_data->hw_control = can_hw_control() is
> currently called only from netdev_led_attr_store(), i.e. when writing any
> sysfs attribute of the netdev trigger instance associated with a PHY LED.
>
> The can_hw_control() calls validate_net_dev() which internally calls
> led_cdev->hw_control_get_device(), which is phy_led_hw_control_get_device()
> for PHY LEDs. The phy_led_hw_control_get_device() returns NULL if the PHY
> is not attached.
>
> At least in case of DWMAC (STM32MP, iMX8M, ...), the PHY device is attached
> only when the interface is brought up and is detached again when the
> interface is brought down. In case e.g. udev rules configure the netdev
> LED trigger sysfs attributes before the interface is brought up, then when
> the interface is brought up, the LEDs are not blinking.
>
> This is because trigger_data->hw_control = can_hw_control() was called
> when udev wrote the sysfs attribute files, before the interface was up,
> so can_hw_control() resp. validate_net_dev() returned false, and the
> trigger_data->hw_control = can_hw_control() was never called again to
> update the trigger_data->hw_control content and let the offload take
> over the LED blinking.
>
> Call data->hw_control = can_hw_control() from netdev_trig_notify() to
> update the offload capability of the LED when the UP notification arrives.
> This makes the LEDs blink after the interface is brought up.
>
> On STM32MP13xx with RTL8211F, it is enough to have the following udev rule
> in place, boot the machine with cable plugged in, and the LEDs won't work
> without this patch once the interface is brought up, even if they should:
> "
> ACTION=="add", SUBSYSTEM=="leds", KERNEL=="stmmac-0:01:green:wan", ATTR{trigger}="netdev", ATTR{link_10}="1", ATTR{link_100}="1", ATTR{link_1000}="1", ATTR{device_name}="end0"
> ACTION=="add", SUBSYSTEM=="leds", KERNEL=="stmmac-0:01:yellow:wan", ATTR{trigger}="netdev", ATTR{rx}="1", ATTR{tx}="1", ATTR{device_name}="end0"
> "
>
> Signed-off-by: Marek Vasut <marex@xxxxxxx>
Reviewed-by: Andrew Lunn <andrew@xxxxxxx>
Andrew
