From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A7F5C00528 for ; Fri, 4 Aug 2023 09:43:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231127AbjHDJna (ORCPT ); Fri, 4 Aug 2023 05:43:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48598 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230267AbjHDJn2 (ORCPT ); Fri, 4 Aug 2023 05:43:28 -0400 Received: from mail-ej1-x629.google.com (mail-ej1-x629.google.com [IPv6:2a00:1450:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14B3B30EA for ; Fri, 4 Aug 2023 02:43:27 -0700 (PDT) Received: by mail-ej1-x629.google.com with SMTP id a640c23a62f3a-997c4107d62so265375466b.0 for ; Fri, 04 Aug 2023 02:43:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1691142205; x=1691747005; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=1eXbT/KalONwMKPKZfZFiDNuA7l+qr3D7lfU+28kCBQ=; b=tMxDCZWY4gGhkYmTyR60h5DpxZNyiNEUht4LfLAAdA11c0Kqdw3ikJKKMIyM896WAt gDMhvRVATOEUC5X/iVQRbktG4S9VmMu3Bi9mN08wC9qnclDiiwdJWl+Wi+qPPlCH8xgl HEm4PDd9L4OfgCxWsotTw2FhEcWsz/i4dO4C3Rh/z6mZuNW0G4pCALsb19iNHwvuZCnk KfDIUzh5b7jXddXqr7bTXpzCg3MMTe27rZvrEBqZrIEyK5c9VHWxa8yguOIbQg4bFtIG lFY2dZXiwIoP45xY5V2dnJb7/0MofSxb838NMEldTDg9Aa0fNmak4J/mbo+VRtocfJoW PBdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691142205; x=1691747005; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1eXbT/KalONwMKPKZfZFiDNuA7l+qr3D7lfU+28kCBQ=; b=UvI6yQ0MuG00XC3daxUR6XyxdCe6DDA3KtW9RmCzi1Hw8izo7KJV06k+QfFhFLr82g D0LTTuB8N82TfHd19YLLyqEB+0wgKUM81rTg5PZ+kNISBRtAJpuc2TnFxCDtW4nCG5Mi hmqOmgmMIhj0+YaxQpmhP+7PVYJ6ijxHZm8LNIJB7pY14DQUL5ASXwHqn343xepgNZDl xOTEpEzgobLPGQBKB7JkBgRmdDTWs/HSoWmZ/iyeHDPbLF/jwpePKUnxmRX0zk0uK3Pq liAMiiDMxj1CSN0AqUbE8wntvs3VZJxnPPKa3tNZ4l8068ipDEBBe0qi99jUyftrzQns FQqA== X-Gm-Message-State: AOJu0YzX+WO/eu/6CAH4iiYVdwoWEarHa7iRbEHHL1995fW03TFBI+fD o/OBeLObFcLgBhpAAry6rN1qaA== X-Google-Smtp-Source: AGHT+IGC9mA7LPO2N64IIl+Xk6+A/e9ohIrzJGE8pgrJFcZhD7dVNL2lN7+hweJBbOWw01HxcF6Slg== X-Received: by 2002:a17:906:28a:b0:99b:d178:f051 with SMTP id 10-20020a170906028a00b0099bd178f051mr893587ejf.64.1691142205545; Fri, 04 Aug 2023 02:43:25 -0700 (PDT) Received: from [192.168.1.20] ([178.197.222.245]) by smtp.gmail.com with ESMTPSA id gs10-20020a170906f18a00b0097404f4a124sm1059389ejb.2.2023.08.04.02.43.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Aug 2023 02:43:25 -0700 (PDT) Message-ID: Date: Fri, 4 Aug 2023 11:43:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: [PATCH V1] arm64: dts: qcom: sa8775p-ride: Remove min and max voltages for L8A Content-Language: en-US To: "Naveen Kumar Goud Arepalli (QUIC)" , Andrew Halaney Cc: "Nitin Rawat (QUIC)" , "agross@kernel.org" , "andersson@kernel.org" , "konrad.dybcio@linaro.org" , "robh+dt@kernel.org" , "krzysztof.kozlowski+dt@linaro.org" , "conor+dt@kernel.org" , "linux-arm-msm@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20230725100007.14775-1-quic_narepall@quicinc.com> <516a54da44724001895f7e50634ad884@quicinc.com> <33232e22-1014-2670-47f6-712b0acc929d@linaro.org> <78e6233799f54428b6601896b8bd7b5c@quicinc.com> From: Krzysztof Kozlowski In-Reply-To: <78e6233799f54428b6601896b8bd7b5c@quicinc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 04/08/2023 10:04, Naveen Kumar Goud Arepalli (QUIC) wrote: >>> diff --git a/arch/arm64/boot/dts/qcom/sa8775p-ride.dts >>> b/arch/arm64/boot/dts/qcom/sa8775p-ride.dts >>> index ed76680410b4..6f3891a09e59 100644 >>> --- a/arch/arm64/boot/dts/qcom/sa8775p-ride.dts >>> +++ b/arch/arm64/boot/dts/qcom/sa8775p-ride.dts >>> @@ -98,8 +98,6 @@ >>> >>> vreg_l8a: ldo8 { >>> regulator-name = "vreg_l8a"; >>> - regulator-min-microvolt = <2504000>; >>> - regulator-max-microvolt = <3300000>; >>> regulator-initial-mode = ; >>> regulator-allow-set-load; >>> regulator-allowed-modes = >> -- >>> 2.17.1 >>> >> >> Reviewing with very little expertise in the area.... >> A few questions below that would help me understand this a bit better. >> >> Does it make sense to *not* set the range of the regulator at all?: >>>>> Yes, we are removing the range of the regulator. >> >> 1. A board dts knows its UFS device >> 2. Is UFS backwards compatible with respect to UFS2/UFS3? >> I don't know how the version is determined, but if it's a >> "start at UFS2, go to UFS3" should it be scaled as that goes? >> >>>> For a UFS device 3.x, we cannot start as UFS 2.0. vcc has to be as per UFS 3.x recommendations. >> >> Relying on the bootloader to set up the device before the kernel >> starts seems like a direction that should be actively avoided instead >> of depended on in my opinion. > > I have trouble finding which part is your reply and which is quote of Andrew. Please reconfigure your mail client. Who said this? Me or you? I am pretty sure I *said this*. Not only you pasted it as your reply, but you also re-wrapped lines. That's not how email communication works outside of corporate structure. Please, don't bring Outlook style to our lives... > >>>>>> As per upstream UFS driver, voltage voting is not there and we vote only for enable/disable . >> Since UFS is the only client in Linux for this rail (L8A ), we don't >> need min and max range to support UFS 2.x and 3.x cards. > > I would assume some reasonable range is always desired. Why it cannot be the wider range from both? 2.4 - 3.6? Again - who said that? I am 100% sure that me, not you. > > Wider range cannot be mentioned in DT, For UFS 2.x range is 2.7 V to 3.6 V and for UFS 3.x range is 2.4V to 2.7V. > Giving the wider range will not set the correct voltage. So is this your reply? I don't see a problem in wider range... > > For example: > If the range is mentioned as 2.4V to 3.6V in DT and we have connected UFS 2.x device, Since UFS driver is voting only for > regulator_enable(voltage is not being set) the voltage will be 2.4V(min voltage) from pmic driver which is wrong voltage for > UFS 2.x devices, which is violation of spec. So what is your solution? Remove constraints? Then who configures them? You rely on bootloader which is not what we want. Best regards, Krzysztof