[PATCH v2 1/3] clk: thead: add support for enabling/disabling PLLs

[Drew Fustini]

On Wed, Aug 13, 2025 at 03:27:00PM +0800, Icenowy Zheng wrote:
> The 2nd control word of T-Head TH1520 PLLs contains a bit to put the VCO
> into reset state, which means disabling the PLL.
> 
> Some PLLs are put to disabled state by the bootloader, and the clock
> driver should be able to enable them.
> 
> Add support for enabling/disabling PLLs. PLLs other than DPU ones are
> set CLK_IS_CRITICAL to prevent killing the system -- they're meant to
> drive CPU or system buses (even the GMAC/Video ones are driving arbitrary
> buses).

Do you think there is a way in the future to allow disabling PLLs for
run-time power management?  I think it is more important right now to
get hardware peripherals working upstream like you are doing, but I was
curious if there is the potential to do something more granular in the
future.

> Signed-off-by: Icenowy Zheng <uwu at icenowy.me>
> ---
> No changes in v2.
> 
>  drivers/clk/thead/clk-th1520-ap.c | 38 +++++++++++++++++++++++++++----
>  1 file changed, 33 insertions(+), 5 deletions(-)

Reviewed-by: Drew Fustini <fustini at kernel.org>