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From: Shashank Balaji <shashank.mahadasyam@sony.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>,
	 Viresh Kumar <viresh.kumar@linaro.org>,
	Jonathan Corbet <corbet@lwn.net>
Cc: linux-pm@vger.kernel.org, linux-doc@vger.kernel.org,
	 linux-kernel@vger.kernel.org,
	Shinya Takumi <shinya.takumi@sony.com>,
	 20250522-userspace-governor-doc-v1-1-c8a038e39084@sony.com,
	 Shashank Balaji <shashank.mahadasyam@sony.com>
Subject: [PATCH v2 1/2] cpufreq: userspace: set CPUFREQ_GOV_STRICT_TARGET flag
Date: Tue, 27 May 2025 21:59:09 +0900	[thread overview]
Message-ID: <20250527-userspace-governor-doc-v2-1-0e22c69920f2@sony.com> (raw)
In-Reply-To: <20250527-userspace-governor-doc-v2-0-0e22c69920f2@sony.com>

When the userspace governor is used, the user intends to set a fixed CPU
frequency for a policy, for whatever reason. The CPUFREQ_GOV_STRICT_TARGET
flag is the required behaviour. Without this flag, the intel_pstate driver,
with HWP enabled, will set HWP_MIN_PERF to the target frequency and HWP_MAX_PERF
to the policy maximum, when configuring the HWP_REQUEST MSR. This lets the
hardware choose any frequency between the target frequency and the policy
maximum, which is not the intended behaviour. To fix this,
`cat scaling_setspeed > scaling_max_freq` had to be done. With this patch, that
is no longer necessary. Setting scaling_setspeed is sufficient, as expected.

Signed-off-by: Shashank Balaji <shashank.mahadasyam@sony.com>
---
 drivers/cpufreq/cpufreq_userspace.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/cpufreq/cpufreq_userspace.c b/drivers/cpufreq/cpufreq_userspace.c
index 2c42fee76daa808f0cd1c7b1ab85476e695082e9..77d62152cd386d0eea69eba347b39f055ec860ce 100644
--- a/drivers/cpufreq/cpufreq_userspace.c
+++ b/drivers/cpufreq/cpufreq_userspace.c
@@ -134,6 +134,7 @@ static struct cpufreq_governor cpufreq_gov_userspace = {
 	.store_setspeed	= cpufreq_set,
 	.show_setspeed	= show_speed,
 	.owner		= THIS_MODULE,
+	.flags		= CPUFREQ_GOV_STRICT_TARGET,
 };
 
 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "

-- 
2.43.0


  reply	other threads:[~2025-05-27 13:00 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-05-27 12:59 [PATCH v2 0/2] cpufreq: userspace: add " Shashank Balaji
2025-05-27 12:59 ` Shashank Balaji [this message]
2025-05-27 12:59 ` [PATCH v2 2/2] cpufreq, docs: userspace: mention variation in freq due to hw coordination Shashank Balaji
2025-06-17 10:14 ` [PATCH v2 0/2] cpufreq: userspace: add CPUFREQ_GOV_STRICT_TARGET flag Shashank Balaji
2025-06-18 19:35 ` Rafael J. Wysocki

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