From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 179BD2AE74; Fri, 8 Aug 2025 09:39:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754645966; cv=none; b=nHXSWggWkFWzIvqZA4+FeAbeRzZIXFQHiKdItbEY4eTHMeHPdHJUwjMrlReCVxdMAbZD79ROr7WFuN0iNds99R0l/AcSyVfINiHbe/zgV0tIZLMW+hlNacoyQJvKBOU+P9SjyyqkNwpgR4pRbCI6A+RoprsCXtXSbBSdC29hoDE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754645966; c=relaxed/simple; bh=2ZfGe5j/wyjBFLdMrPOZgs+eBxwkgsC8XOn4yjPUPlc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EdI98rh0GJA9+J30LGyQ/k9jKNfnJVCA22XgQkRfkvespHIYipEd94zVPKwxnBL+3DHo/N7e/bdbT3fSh5OGmitb7b0uZoT8u+kzfnLFbcimyqpbToqekoFtuvV5A49m7QysrlP2Zg1nYqHJqM3bmQ8qzoU6eE4KIW6VcJ/jrgA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qomvNQ/N; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qomvNQ/N" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0DF30C4CEED; Fri, 8 Aug 2025 09:39:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754645965; bh=2ZfGe5j/wyjBFLdMrPOZgs+eBxwkgsC8XOn4yjPUPlc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=qomvNQ/NxywIDtXIjXPrrQ03yu9zW+90DeVin/d5GWQ4L+isCsmjrubnkqMOQbNWF J/6tokkj2r0/6P5PCy7kynjBGwhd8jCn7iszKchLdwyJfGP5MS3tiqDjlrKLCLiTr3 YI2F5EbIBu6OMZwlamL/dGJClQvAda+Hw8cxWSB/JIVH8sw1wuLLY3TIMCDBfrMdQ2 8IP1SUsDxEBuC+1qCunTZPk3PwGHjJH8mqNPN5ghjLEGCG4fNCWDkQLXwGRd2kCnZX XuCW+KcAjh9bJgwfo0jNYANdUokXDEvJFglQGLw9RAA3DJS7xUMnmAiyaCbFKrgNGI KJp6L2SH93mIQ== Message-ID: <292907f3-25d6-40d9-be6e-b6b83e646d73@kernel.org> Date: Fri, 8 Aug 2025 11:39:20 +0200 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 V1 2/4] arm64: dts: qcom: sm8750: add max-microamp for UFS PHY and PLL supplies To: Konrad Dybcio , Nitin Rawat Cc: vkoul@kernel.org, kishon@kernel.org, mani@kernel.org, conor+dt@kernel.org, bvanassche@acm.org, andersson@kernel.org, neil.armstrong@linaro.org, dmitry.baryshkov@oss.qualcomm.com, konradybcio@kernel.org, krzk+dt@kernel.org, linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org References: <20250806154340.20122-1-quic_nitirawa@quicinc.com> <20250806154340.20122-3-quic_nitirawa@quicinc.com> <20250808-calm-boa-of-swiftness-a4a7ce@kuoka> <9af71063-0629-4ccc-bc76-3fb588677bf4@oss.qualcomm.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 08/08/2025 10:58, Konrad Dybcio wrote: > On 8/8/25 9:29 AM, Krzysztof Kozlowski wrote: >> On Wed, Aug 06, 2025 at 09:13:38PM +0530, Nitin Rawat wrote: >>> Add `vdda-phy-max-microamp` and `vdda-pll-max-microamp` properties to >>> the UFS PHY node in the device tree. >>> >>> These properties define the maximum current (in microamps) expected >>> from the PHY and PLL regulators. This allows the PHY driver to >>> configure regulator load accurately and ensure proper regulator >>> mode based on load requirements. >> >> That's not the property of phy, but regulator. >> >> Also reasoning is here incomplete - you just post downstream code. :/ > > The reason for this change is good, but perhaps not explained clearly > > All of these values refer to the maximum current draw that needs to be > allocated on a shared voltage supply for this peripheral (because the It sounds very different than how much it can be drawn. How much can be drawn is the property of the regulator. The regulator knows how much current it can support. > supply's capabilities change depending on the maximum potential load > at any given time, which the regulator driver must be aware of) > > This is a property of a regulator *consumer*, i.e. if we had a chain > of LEDs hanging off of this supply, we'd need to specify NUM_LEDS * > MAX_CURR under the "led chain" device, to make sure that if the > aggregated current requirements go over a certain threshold (which is > unknown to Linux and hidden in RPMh fw), the regulator can be > reconfigured to allow for a higher current draw (likely at some > downgrade to efficiency) The problem is that rationale is downstream. Instead I want to see some reason: e.g. datasheets, spec, type of UFS device (that was the argument in the driver patch discussion). The only argument here for given value is: downstream has it. Best regards, Krzysztof