From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: seanwang1 <seanwang1@lenovo.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Sudeep Holla <sudeep.holla@kernel.org>,
rafael@kernel.org, Danilo Krummrich <dakr@kernel.org>,
Lifeng Zheng <zhenglifeng1@huawei.com>,
Beata Michalska <beata.michalska@arm.com>,
Xuewen Yan <xuewen.yan@unisoc.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Sumit Gupta <sumitg@nvidia.com>,
Yunhui Cui <cuiyunhui@bytedance.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, driver-core@lists.linux.dev
Subject: Re: [PATCH v2] arm64: topology: add source check in arch_cpu_idle_enter()
Date: Mon, 10 Aug 2026 13:37:44 +0200 [thread overview]
Message-ID: <2026081025-rummage-rifling-982e@gregkh> (raw)
In-Reply-To: <20260810102006.9986-1-seanwang1@lenovo.com>
On Mon, Aug 10, 2026 at 06:20:06PM +0800, seanwang1 wrote:
> arch_cpu_idle_enter() directly calls amu_scale_freq_tick() to update
> arch_freq_scale when a CPU enters idle. This bypasses the sft_data
> pointer check that topology_clear_scale_freq_source() relies on.
>
> As a result, even after calling topology_clear_scale_freq_source()
> with SCALE_FREQ_SOURCE_ARCH to disable AMU-based frequency scaling,
> the arch_freq_scale value can still be modified by AMU counters when
> the CPU goes idle through the arch_cpu_idle_enter() path.
>
> Add topology_scale_freq_source() helper to check whether a specific
> frequency scaling source is currently registered for a CPU. Use it
> in arch_cpu_idle_enter() to verify that AMU is the active source
> before calling amu_scale_freq_tick().
>
> This ensures that topology_clear_scale_freq_source() properly
> disables AMU updates in both the tick path (already handled by
> topology_scale_freq_tick()) and the idle path.
>
> Co-developed-by: Xuewen Yan <xuewen.yan@unisoc.com>
> Signed-off-by: Sean Wang <seanwang1@lenovo.com>
> Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
> ---
The From: line does not match your signed-off-by name :(
next prev parent reply other threads:[~2026-08-10 11:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-10 10:20 [PATCH v2] arm64: topology: add source check in arch_cpu_idle_enter() seanwang1
2026-08-10 11:37 ` Greg Kroah-Hartman [this message]
2026-08-10 15:04 ` Sumit Gupta
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