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From: Jie Zhan <zhanjie9@hisilicon.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>,
	Linux PM <linux-pm@vger.kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>,
	Qais Yousef <qyousef@layalina.io>,
	LKML <linux-kernel@vger.kernel.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Pierre Gondois <pierre.gondois@arm.com>,
	Mario Limonciello <mario.limonciello@amd.com>,
	Linux ACPI <linux-acpi@vger.kernel.org>
Subject: Re: [PATCH v3 2/4] cpufreq: CPPC: Avoid using CPUFREQ_ETERNAL as transition delay
Date: Sun, 28 Sep 2025 09:59:02 +0800	[thread overview]
Message-ID: <e01fef03-65cd-4eb6-be48-974bcd59ae23@hisilicon.com> (raw)
In-Reply-To: <3406003.44csPzL39Z@rafael.j.wysocki>



On 9/26/2025 6:19 PM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> If cppc_get_transition_latency() returns CPUFREQ_ETERNAL to indicate a
> failure to retrieve the transition latency value from the platform
> firmware, the CPPC cpufreq driver will use that value (converted to
> microseconds) as the policy transition delay, but it is way too large
> for any practical use.
> 
> Address this by making the driver use the cpufreq's default
> transition latency value (in microseconds) as the transition delay
> if CPUFREQ_ETERNAL is returned by cppc_get_transition_latency().
> 
> Fixes: d4f3388afd48 ("cpufreq / CPPC: Set platform specific transition_delay_us")
> Cc: 5.19+ <stable@vger.kernel.org> # 5.19
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Jie Zhan <zhanjie9@hisilicon.com>
> ---
> 
> v1 -> v3:
>    * Change the name of the new function (Jie Zhan)
>    * Add a tag from Mario Limonciello
> 
> ---
>  drivers/cpufreq/cppc_cpufreq.c |   14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)

  reply	other threads:[~2025-09-28  1:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-26 10:04 [PATCH v3 0/4] cpufreq: Fixes and cleanups related to CPUFREQ_ETERNAL Rafael J. Wysocki
2025-09-26 10:12 ` [PATCH v3 1/4] cpufreq: Make drivers using CPUFREQ_ETERNAL specify transition latency Rafael J. Wysocki
2025-09-28  3:23   ` Shawn Guo
2025-09-28 10:00     ` Rafael J. Wysocki
2025-09-29  3:14       ` Shawn Guo
2025-10-01 10:38   ` Qais Yousef
2025-09-26 10:19 ` [PATCH v3 2/4] cpufreq: CPPC: Avoid using CPUFREQ_ETERNAL as transition delay Rafael J. Wysocki
2025-09-28  1:59   ` Jie Zhan [this message]
2025-09-26 10:29 ` [PATCH v3 3/4] ACPI: CPPC: Do not use CPUFREQ_ETERNAL as an error value Rafael J. Wysocki
2025-09-26 10:31 ` [PATCH v3 4/4] cpufreq: Drop unused symbol CPUFREQ_ETERNAL Rafael J. Wysocki

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