From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from madrid.collaboradmins.com (madrid.collaboradmins.com [46.235.227.194]) (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 D17B4568C; Tue, 2 Jan 2024 09:09:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="P94UWCDe" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1704186572; bh=0IJc2UOGZ6oMEAmRyC8mL1X+nZIu6VgIRz8xHSvM2KI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=P94UWCDeEk5DKNB6KMkv3dEvRD8cI6BmKuy/6krHuaJB+1o+zwQoDoGEVvPdZdaaD 8VcqkRQfLaqEvHgRFs7agU3FTdKAfkJlamVTamOQVIwdt3uSITjLpAetWlPu80wFZf uehhpHxvakYiX8ZVTA1yaTuC+CnAk83nY9E6433BXB/8Dj76LWc+nBQLEpnvdL5FFT 3jCWAxT7A9JLv4GDNjxCiZ6usIkmyBpWZEdnPCvRwBIpdEYsPeyeyrZd+Wafw3eb3T Fjk8QOqTY53UaB+3ahZDRfpHG77yfGQfiQNVSI+HHhO2EY4wYIXPvZ5runNQEXVMxp B0uah6DH1q7vg== Received: from [100.113.186.2] (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by madrid.collaboradmins.com (Postfix) with ESMTPSA id 4C3C237804B2; Tue, 2 Jan 2024 09:09:31 +0000 (UTC) Message-ID: Date: Tue, 2 Jan 2024 10:09:30 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] arm64: dts: mediatek: cherry: Add CPU supply dependency to cpufreq-hw To: Viresh Kumar , =?UTF-8?B?TsOtY29sYXMgRi4gUi4gQS4gUHJhZG8=?= Cc: "Rafael J . Wysocki" , kernel@collabora.com, Conor Dooley , Krzysztof Kozlowski , Matthias Brugger , Rob Herring , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org References: <20231229212853.277334-1-nfraprado@collabora.com> <20231229212853.277334-2-nfraprado@collabora.com> <20240102061123.frvwltggqqh6m7pm@vireshk-i7> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: <20240102061123.frvwltggqqh6m7pm@vireshk-i7> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Il 02/01/24 07:11, Viresh Kumar ha scritto: > On 29-12-23, 18:28, Nícolas F. R. A. Prado wrote: >> When the mediatek-cpufreq-hw driver enables the hardware (by >> writing to REG_FREQ_ENABLE), if the regulator supplying the voltage to >> the big CPUs hasn't probed yet, the platform hangs shortly after and >> "rcu: INFO: rcu_preempt detected stalls on CPUs/tasks" are printed in >> the log. >> >> To prevent this from happening, describe the big CPUs regulator in the >> performance-controller DT node, so that devlink ensures the regulator >> has been probed and configured before the frequency scaling hardware is >> probed and enabled. >> >> Signed-off-by: Nícolas F. R. A. Prado >> >> --- >> >> arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi >> index dd5b89b73190..505da60eee90 100644 >> --- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi >> +++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi >> @@ -502,6 +502,10 @@ &pcie1 { >> pinctrl-0 = <&pcie1_pins_default>; >> }; >> >> +&performance { >> + big-cpus-supply = <&mt6315_6_vbuck1>; >> +}; >> + >> &pio { >> mediatek,rsel-resistance-in-si-unit; >> pinctrl-names = "default"; > > I think the regulator needs to be mentioned in the CPU's node and not > here ? > Even if the regulator voltage is being changed by firmware with cpufreq-hw, the actual regulators should go to each CPU node and not in the cpufreq driver node, I agree with Viresh. Besides, that's the same thing that we're doing with mediatek-cpufreq as well... and since we're talking about that, we should also do something about this such that we stop declaring `regulator-always-on` for CPU cores in devicetree, but this is probably slightly out of context for what you're trying to do here, so, read that as an "extra consideration" :-) Cheers, Angelo