From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-m16.yeah.net (mail-m16.yeah.net [220.197.32.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A9BC92FF15D; Mon, 15 Sep 2025 12:21:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.32.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757938908; cv=none; b=qWRGAHV9GrZ2XJ1XZZc/n51uhOK/GNpJWDm6q5CLW7TWXW41o15eHwC+mr99ur9/dtwqin/sT1p55LJpUwQXoiPvfcfJE7BQxkfndkQMAuPkTHGhLyCjTRSo/YyBwLtScF4E1oAUqsuHnQ3Ej0cl3zVwm1OPNBtqj1lHFTv2Fag= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757938908; c=relaxed/simple; bh=z2kNIlcXBW6MfC2xnrcVa0oHxwllCrJCejQCNVLE0eQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZiH9A/Vmohr2aOxV5Bv8HE1n1yWRhdHuv31Wr9lJ/6dYcwoQNJK1s/z8ASoiaZmLiSt5Ro7Pl72S7eR5W23nILJCCfwjDq8oJmGN2mckG1yJA0FUzPYJ5liVCxJR+7fH5sxjlLYSRa8VCwsY+KH+dZ+jWT94p9x1TddCqCry9ic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=yeah.net; spf=pass smtp.mailfrom=yeah.net; dkim=pass (1024-bit key) header.d=yeah.net header.i=@yeah.net header.b=jrFESGPW; arc=none smtp.client-ip=220.197.32.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=yeah.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=yeah.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=yeah.net header.i=@yeah.net header.b="jrFESGPW" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yeah.net; s=s110527; h=Date:From:To:Subject:Message-ID:MIME-Version: Content-Type; bh=OOyfLZgtX27UDIP2iLeBPK7IHVGLm6yCXP8suJxPQlk=; b=jrFESGPWhXpollyfx2m2Rmh87nxknxI0bHyUfUBTA7k8Zz0Jk6COaBKi03L4dr I/WOcZ6ziU5uN2cHpS83VNHtD/12Jduq12MQIgeUSo9BAs7jjeUHXdEG6fBpvZa0 aa5V28EzrTFTAgUQpbIXpKUut6KGamE3qez/pMsnrO1SQ= Received: from dragon (unknown []) by gzsmtp1 (Coremail) with SMTP id Mc8vCgB3b7qDBMhoodmEBA--.36439S3; Mon, 15 Sep 2025 20:20:20 +0800 (CST) Date: Mon, 15 Sep 2025 20:20:18 +0800 From: Shawn Guo To: Qais Yousef Cc: "Rafael J. Wysocki" , Viresh Kumar , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Shawn Guo , stable@vger.kernel.org Subject: Re: [PATCH] cpufreq: cap the default transition delay at 10 ms Message-ID: References: <20250910065312.176934-1-shawnguo2@yeah.net> <20250914174326.i7nqmrzjtjq7kpqm@airbuntu> <20250915100207.5amkmknirijnvuoh@airbuntu> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250915100207.5amkmknirijnvuoh@airbuntu> X-CM-TRANSID:Mc8vCgB3b7qDBMhoodmEBA--.36439S3 X-Coremail-Antispam: 1Uf129KBjvJXoW7try8Ww1fWrWDKFyDAw48Crg_yoW8GF43pF W7K3W2kF1kGF4Dtws2yw4Uuw1Ykwn5tr4UGry8WF1rA398Wrn0gw4Iga1Y9FW3Jr4DCw1q qr40g3srZayYyaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07Ut9N3UUUUU= X-CM-SenderInfo: pvkd40hjxrjqh1hdxhhqhw/1tbiEh3JZWjHo9vN3AABsk On Mon, Sep 15, 2025 at 11:02:07AM +0100, Qais Yousef wrote: > On 09/15/25 15:29, Shawn Guo wrote: > > On Sun, Sep 14, 2025 at 06:43:26PM +0100, Qais Yousef wrote: > > > > > Why do you want to address the issue in the cpufreq core instead of > > > > > doing that in the cpufreq-dt driver? > > > > > > > > My intuition was to fix the regression at where the regression was > > > > introduced by recovering the code behavior. > > > > > > Isn't the right fix here is at the driver level still? We can only give drivers > > > what they ask for. If they ask for something wrong and result in something > > > wrong, it is still their fault, no? > > > > I'm not sure. The cpufreq-dt driver is following suggestion to use > > CPUFREQ_ETERNAL, which has the implication that core will figure out > > a reasonable default value for platforms where the latency is unknown. > > And that was exactly the situation before the regression. How does it > > become the fault of cpufreq-dt driver? > > Rafael and Viresh would know better, but amd-pstate chooses to fallback to > specific values if cppc returned CPUFREQ_ETERNAL. > > Have you tried to look why dev_pm_opp_get_max_transition_latency() returns > 0 for your platform? I think this is the problem that was being masked before. My platform doesn't scale voltage along with frequency, and the platform DT doesn't specify 'clock-latency-ns' which is an optional property after all. Shawn