Enable pwm-fan and set default thermal policy to STEP_WISE

[hbiyik]

This is necessary for rock5b pwm fan to operate

[RadxaYuntian]

This kernel and config file is shared with multiple products which may not include a fan, and even in case of 5B
the fan is an optional add-on. This is why the default thermal governor is power_allocator which operates passively.

pwm-fan is enabled globally in our bsp build script to ensure a consistent feature set across different kernel versions. It doesn't hurt to enable it here as well.

[hbiyik]

ok this means that i am building Archlinux kernels wrong. I was only using $BSP_DEFCONFIG, which is rockchip_linux_defconfig. But after analyzing your comment, i noticed that .common/kconfig.conf is merged with scripts/Kconfig/merge_config.sh merged on top of rockchip_linux_defconfig.

This should mean that .deb package of latest kernel which is rkr3.4 based should also have this enabled, is my understanding correct?

[RadxaYuntian]

This is correct and we have working PWM fan support in 5A and 5B for a while.

[hbiyik]

ok then closing this PR, thanks for clearifactions..