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Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tLJPZ-0000000EUs0-0RoD; Wed, 11 Dec 2024 09:53:41 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tLJOF-0000000EUbx-3e5s for linux-phy@lists.infradead.org; Wed, 11 Dec 2024 09:52:21 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id E2F8C5C10A1; Wed, 11 Dec 2024 09:51:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A2E1CC4CEDE; Wed, 11 Dec 2024 09:52:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733910739; bh=1MvPVOm2KT4I3D3hDmh8qUenmdswE/c+r2gVB3m84Fk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=BZCNOb9F091Lge08SDZcjO25UI/Ji+Hkv0ozwWHtSXP/7LtzkHkpCUVpxB3+JuWG8 cBw41kTpv9gpt99Iy4Rq/4rurBdoeAdifDKR+N39lQBudF6QMu43DndXVIj7184C7i i84xVfDLYCc2jjjxnAQ9478drcrZl5ciES4jDCXk+kC190/WUygReGVB67YL4EyGAZ kfDb/uo/pbXmwgKVXXUH1MRLpSf24mp5BY1lTmnpvwsexZRZhd1LaR4krT9l5lOnqk IiZKKYSPChXvKAABvVqKb+/ChHWLoH63DCwpCE1S7cA62X1mjTaIv3wrdaBXKkX0wc PuDnMGpPriC/g== Message-ID: <3c7ddb08-38db-44b3-a7a7-ec7b270a408f@kernel.org> Date: Wed, 11 Dec 2024 10:52:11 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] dt-bindings: phy: qcom,qmp-pcie: add optional current load properties To: Manivannan Sadhasivam Cc: Ziyue Zhang , vkoul@kernel.org, kishon@kernel.org, dmitry.baryshkov@linaro.org, abel.vesa@linaro.org, neil.armstrong@linaro.org, andersson@kernel.org, konradybcio@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org References: <20241204105249.3544114-1-quic_ziyuzhan@quicinc.com> <20241204105249.3544114-2-quic_ziyuzhan@quicinc.com> <20241211062053.vxdpovlmetvyx3za@thinkpad> <33697bd9-02f4-4a9a-b8c0-4930d7fdaee2@kernel.org> <20241211082404.p7fbmhooikmipxvm@thinkpad> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org On 11/12/2024 09:24, Manivannan Sadhasivam wrote: > On Wed, Dec 11, 2024 at 09:09:18AM +0100, Krzysztof Kozlowski wrote: >> On 11/12/2024 07:20, Manivannan Sadhasivam wrote: >>> On Thu, Dec 05, 2024 at 11:23:11AM +0100, Krzysztof Kozlowski wrote: >>>> On Wed, Dec 04, 2024 at 06:52:47PM +0800, Ziyue Zhang wrote: >>>>> On some platforms, the power supply for PCIe PHY is not able to provide >>>>> enough current when it works in LPM mode. Hence, PCIe PHY driver needs to >>>>> set current load to vote the regulator to HPM mode. >>>>> >>>>> Document the current load as properties for each power supply PCIe PHY >>>>> required, namely vdda-phy-max-microamp, vdda-pll-max-microamp and >>>>> vdda-qref-max-microamp, respectively.PCIe PHY driver should parse them to >>>>> set appropriate current load during PHY power on. >>>>> >>>>> This three properties are optional and not mandatory for those platforms >>>>> that PCIe PHY can still work with power supply. >>>> >>>> >>>> Uh uh, so the downstream comes finally! >>>> >>>> No sorry guys, use existing regulator bindings for this. >>>> >>> >>> Maybe they got inspired by upstream UFS bindings? >>> Documentation/devicetree/bindings/ufs/ufs-common.yaml: >>> >>> vcc-max-microamp >>> vccq-max-microamp >>> vccq2-max-microamp >> >> And it is already an ABI, so we cannot do anything about it. >> >>> >>> Regulator binding only describes the min/max load for the regulators and not >> >> No, it exactly describes min/max consumers can use. Let's quote: >> "largest current consumers may set" >> It is all about consumers. >> >>> consumers. What if the consumers need to set variable load per platform? Should >> >> Then each platform uses regulator API or regulator bindings to set it? I >> don't see the problem here. >> >>> they hardcode the load in driver? (even so, the load should not vary for each >>> board). >> >> The load must vary per board, because regulators vary per board. Of >> course in practice most designs could be the same, but regulators and >> their limits are always properties of the board, not the SoC. >> > > How the consumer drivers are supposed to know the optimum load? > > I don't see how the consumer drivers can set the load without hardcoding the > values. And I could see from UFS properties that each board has different > values. Drivers do not need to know, it's not the driver's responsibility. If these are constraints per board, then regulator properties apply and there is no difference between this "vdd-max-microamp = 10" and "regulator-max-microamp". If this varies runtime, then your property is already not suitable and very limited and you should use OPP table. Best regards, Krzysztof -- linux-phy mailing list linux-phy@lists.infradead.org https://lists.infradead.org/mailman/listinfo/linux-phy