From: Drew Fustini <fustini@kernel.org>
To: Yao Zi <ziyao@disroot.org>
Cc: Guo Ren <guoren@kernel.org>, Fu Wei <wefu@redhat.com>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Paul Walmsley <pjw@kernel.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Alexandre Ghiti <alex@ghiti.fr>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>, Icenowy Zheng <uwu@icenowy.me>,
linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
Han Gao <rabenda.cn@gmail.com>, Han Gao <gaohan@iscas.ac.cn>
Subject: Re: [PATCH 6/7] clk: thead: th1520-ap: Support CPU frequency scaling
Date: Thu, 27 Nov 2025 14:33:58 -0600 [thread overview]
Message-ID: <aSi1tlmBdZ5fZHqR@gen8> (raw)
In-Reply-To: <20251120131416.26236-7-ziyao@disroot.org>
On Thu, Nov 20, 2025 at 01:14:15PM +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.
>
> To achieve glitchless rate change, customized clock operations are
> implemented for c910_clk: on rate change, the PLL not currently in use
> is configured to the requested rate first, then c910_clk reparents to
> it.
>
> Additionally, c910_bus_clk, which in turn takes c910_clk as parent,
> has a frequency limit of 750MHz. A clock notifier is registered on
> c910_clk to adjust c910_bus_clk on c910_clk rate change.
>
> Signed-off-by: Yao Zi <ziyao@disroot.org>
> ---
> drivers/clk/thead/clk-th1520-ap.c | 148 +++++++++++++++++++++++++++++-
> 1 file changed, 146 insertions(+), 2 deletions(-)
[...]
> +/*
> + * c910_clk could be reparented glitchlessly for DVFS. There are two parents,
> + * - c910_i0_clk, dervided from cpu_pll0_clk or osc_24m.
Typo: 'derived' instead of 'dervided'.
[...]
Unless there are other comments that require changes, I can fix up the
typo when applied.
Reviewed-by: Drew Fustini <fustini@kernel.org>
next prev parent reply other threads:[~2025-11-27 20:34 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-20 13:14 [PATCH 0/7] Implement CPU frequency scaling for TH1520 Yao Zi
2025-11-20 13:14 ` [PATCH 1/7] dt-bindings: clock: thead,th1520-clk-ap: Add ID for C910 bus clock Yao Zi
2025-11-20 18:01 ` Conor Dooley
2025-11-20 13:14 ` [PATCH 2/7] clk: thead: th1520-ap: Poll for PLL lock and wait for stability Yao Zi
2025-11-24 22:08 ` Drew Fustini
2025-11-25 3:19 ` Yao Zi
2025-11-26 14:39 ` Drew Fustini
2025-11-26 14:52 ` Drew Fustini
2025-11-26 15:16 ` Yao Zi
2025-11-20 13:14 ` [PATCH 3/7] clk: thead: th1520-ap: Add C910 bus clock Yao Zi
2025-11-26 15:46 ` Drew Fustini
2025-11-20 13:14 ` [PATCH 4/7] clk: thead: th1520-ap: Support setting PLL rates Yao Zi
2025-11-26 15:46 ` Drew Fustini
2025-11-20 13:14 ` [PATCH 5/7] clk: thead: th1520-ap: Add macro to define multiplexers with flags Yao Zi
2025-11-24 22:14 ` Drew Fustini
2025-11-25 3:25 ` Yao Zi
2025-11-26 15:47 ` Drew Fustini
2025-11-20 13:14 ` [PATCH 6/7] clk: thead: th1520-ap: Support CPU frequency scaling Yao Zi
2025-11-27 20:33 ` Drew Fustini [this message]
2025-11-20 13:14 ` [PATCH 7/7] [Not For Upstream] riscv: dts: thead: Add CPU clock and OPP table for TH1520 Yao Zi
2025-12-19 19:32 ` [PATCH 0/7] Implement CPU frequency scaling " Drew Fustini
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