Re: [PATCH 0/7] Implement CPU frequency scaling for TH1520

Drew Fustini
2026-01-15T01:50:29Z

On Fri, Dec 19, 2025 at 11:32:24AM -0800, Drew Fustini wrote:
> On Thu, Nov 20, 2025 at 01:14:09PM +0000, Yao Zi wrote:
> > On TH1520 SoC, c910_clk feeds the CPU cluster. It could be glitchlessly
> > reparented to one of the two PLLs: either to cpu_pll0 indirectly through
> > c910_i0_clk, or to cpu_pll1 directly. This series fixes a bug in PLL
> > enabling code, supports rate change for PLL, and finally implements
> > frequency scaling support for c910_clk.
> >
> > However, to achieve reliable frequency scaling, CPU voltage must be
> > adjusted together with frequency, and AON-firmware-based PMIC support
> > for TH1520 SoC is still missing in mainline. Thus PATCH 7 that fills OPP
> > table for TH1520 CPU and enables CPUfreq is only for testing purpose,
> > not intended for upstream (yet).
> >
> > Testing is done on Lichee Pi 4A board, only operating points safe
> > to be used with the the default PMIC configuration are enabled in
> > devicetree. I've confirmed there's a performance gain when running
> > coremark and some building work compared to the case without cpufreq.
> >
> > This series is based on next-20251120, thanks for your time and review.
> >
> > Yao Zi (7):
> > dt-bindings: clock: thead,th1520-clk-ap: Add ID for C910 bus clock
> > clk: thead: th1520-ap: Poll for PLL lock and wait for stability
> > clk: thead: th1520-ap: Add C910 bus clock
> > clk: thead: th1520-ap: Support setting PLL rates
> > clk: thead: th1520-ap: Add macro to define multiplexers with flags
> > clk: thead: th1520-ap: Support CPU frequency scaling
> > [Not For Upstream] riscv: dts: thead: Add CPU clock and OPP table for
> > TH1520
> >
> > arch/riscv/boot/dts/thead/th1520.dtsi | 35 ++
> > drivers/clk/thead/clk-th1520-ap.c | 350 +++++++++++++++++-
> > .../dt-bindings/clock/thead,th1520-clk-ap.h | 1 +
> > 3 files changed, 379 insertions(+), 7 deletions(-)
> >
> > --
> > 2.51.2
> >
>
> Applied to thead-clk-for-next, thanks!
>
> [1/7] dt-bindings: clock: thead,th1520-clk-ap: Add ID for C910 bus clock
> https://git.kernel.org/fustini/c/5f352125f8a0

Conor - can I included this binding patch in my thead clk pull request
to Stephen?

Thanks,
Drew