net: dsa: realtek: keep default LED state in rtl8366rb

net: dsa: realtek: keep default LED state in rtl8366rb

This switch family supports four LEDs for each of its six ports. Each
LED group is composed of one of these four LEDs from all six ports. LED
groups can be configured to display hardware information, such as link
activity, or manually controlled through a bitmap in registers
RTL8366RB_LED_0_1_CTRL_REG and RTL8366RB_LED_2_3_CTRL_REG.

After a reset, the default LED group configuration for groups 0 to 3
indicates, respectively, link activity, link at 1000M, 100M, and 10M, or
RTL8366RB_LED_CTRL_REG as 0x5432. These configurations are commonly used
for LED indications. However, the driver was replacing that
configuration to use manually controlled LEDs (RTL8366RB_LED_FORCE)
without providing a way for the OS to control them. The default
configuration is deemed more useful than fixed, uncontrollable turned-on
LEDs.

The driver was enabling/disabling LEDs during port_enable/disable.
However, these events occur when the port is administratively controlled
(up or down) and are not related to link presence. Additionally, when a
port N was disabled, the driver was turning off all LEDs for group N,
not only the corresponding LED for port N in any of those 4 groups. In
such cases, if port 0 was brought down, the LEDs for all ports in LED
group 0 would be turned off. As another side effect, the driver was
wrongly warning that port 5 didn't have an LED ("no LED for port 5").
Since showing the administrative state of ports is not an orthodox way
to use LEDs, it was not worth it to fix it and all this code was
dropped.

The code to disable LEDs was simplified only changing each LED group to
the RTL8366RB_LED_OFF state. Registers RTL8366RB_LED_0_1_CTRL_REG and
RTL8366RB_LED_2_3_CTRL_REG are only used when the corresponding LED
group is configured with RTL8366RB_LED_FORCE and they don't need to be
cleaned. The code still references an LED controlled by
RTL8366RB_INTERRUPT_CONTROL_REG, but as of now, no test device has
actually used it. Also, some magic numbers were replaced by macros.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>