Re: [PATCH 0/5] clk: spacemit: preserve and safely synchronize firmware PLLs

[Jerome Brunet <jbrunet@baylibre.com>]

On mer. 09 sept. 2026 at 22:07, Troy Mitchell <troy.mitchell@linux.spacemit.com> wrote:

> Firmware may leave PLLs running with valid settings absent from Linux's
> rate tables. Replacing those settings during clock registration can
> stop CPUs that depend on them.

A provider should not act on the clock on its own. 

>
> This series removes the init fallback to the first rate-table entry,
> decodes hardware rates directly and preserves unlisted rates. Opt-in
> synchronization applies only to differing parameters for the same
> decoded rate.

Don't think the provider should be responsible for that

> It temporarily moves mapped CPU consumers to validated
> PLL1 branches and restores their parents after the reprogrammed PLL
> locks.

This is typically a use case or policy choice that belong in whatever
consumes the clock. Your DVFS driver maybe ?

> PLL1 itself is not synchronized, and enabled outputs outside the
> managed CPU paths prevent synchronization.
>
> The series also corrects CPU divider and shared-parent modeling and
> makes MIX rate selection agree with programming. Runtime PLL rate
> changes still require a stopped PLL; automatic DVFS switching and new
> rate-table entries are outside this series.
>
> ---
> Troy Mitchell (5):
>       clk: spacemit: derive PLL rates from hardware
>       clk: spacemit: make MIX rate selection consistent
>       clk: spacemit: describe CPU clock dividers and shared PLL muxes
>       clk: spacemit: reject rate changes to running firmware PLLs
>       clk: spacemit: safely synchronize PLL parameters during init
>
>  drivers/clk/spacemit/ccu-k1.c     |  60 +++--
>  drivers/clk/spacemit/ccu-k3.c     | 137 +++++++---
>  drivers/clk/spacemit/ccu_common.c |  12 +
>  drivers/clk/spacemit/ccu_common.h |   2 +
>  drivers/clk/spacemit/ccu_mix.c    |  35 ++-
>  drivers/clk/spacemit/ccu_mix.h    |  18 ++
>  drivers/clk/spacemit/ccu_pll.c    | 535 +++++++++++++++++++++++++++++++-------
>  drivers/clk/spacemit/ccu_pll.h    |  43 ++-
>  8 files changed, 689 insertions(+), 153 deletions(-)
> ---
> base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
> change-id: 20260907-spacemit-pll-init-c942bb249244
>
> Best regards,
> --  
> Troy Mitchell <troy.mitchell@linux.spacemit.com>
>

-- 
Jerome

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