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 0C046C001B0 for ; Wed, 26 Jul 2023 13:07:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232246AbjGZNHH (ORCPT ); Wed, 26 Jul 2023 09:07:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232142AbjGZNHF (ORCPT ); Wed, 26 Jul 2023 09:07:05 -0400 Received: from mail-lj1-x234.google.com (mail-lj1-x234.google.com [IPv6:2a00:1450:4864:20::234]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92B6A1FEC for ; Wed, 26 Jul 2023 06:07:04 -0700 (PDT) Received: by mail-lj1-x234.google.com with SMTP id 38308e7fff4ca-2b74fa5e7d7so98667761fa.2 for ; Wed, 26 Jul 2023 06:07:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1690376823; x=1690981623; 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=3wsh3ywboypSR9IxavTMFwQ0boo9RTAm9WcxI76p9a0=; b=On8Lm3TQuDsqs6FLqYifzbrx1zVIb+8FK1Wv7zFU5QCkStu92wqu6+CMBrGHeYZW5c tAiUG+PXvQXlNbeHJWd6SkUYcCQAZAOoa/iZvt/sRsck7Vuw0Qh3ncJqqPePGuOUtLMT QhsxYyH6w3YUVSCdczi36mv0wzLS2nE5UNOcptd5nj2xpa3zZ8XQfAyz0/46BtgY+oQL zCZ6GHdSxSBp8LeqTifhQEDSM2kjcmn7EGM+zPhK21VyhmNCuQcYEim/+I98JnorxdOs oZ6Axsst7JUaUZx3Sgh6ff+BHpVawV0bsR5GVe47oLeHAd6hOT+d0hEae92AqxovWzeT xrog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690376823; x=1690981623; 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=3wsh3ywboypSR9IxavTMFwQ0boo9RTAm9WcxI76p9a0=; b=LZNV3zGxs+tLkp7y3svT7/6nk0UJrRo+lPYBzfKaLeIp6gBWwefxM/MFiP7qz96gKq qI9Lqz10GGbUyuILdniRzhTMLoU9JQ2cUzxwAw+ov0MnfxznNaTIQG/F1S7hWa1m87AM cZBEO3oDZUN5+w4REk8ks7OSx4WDGd2s0J+d33UWqnU8k/5OPs6M5OYOywVGnbVRMn/W 6MPr5PnhGPVyydn88KIXNUFeTKzjLGo8s8R94UQjpVf4137a1pNZlTmf2+3JMQ3DkPvp TnNQNPRiwxEHAHJa2fuMPO0KCj3GndkvDIazVTrnIkxRJZ31pvN0SLJpQCvUgU931fbM EQIA== X-Gm-Message-State: ABy/qLZW4vqd3U/FN3cUxSF7l/eSN0dGi9dInlypNyn3osWNKUEVkrUC YfDc4/o0L0Uj+SMSJb+A5uVlMg== X-Google-Smtp-Source: APBJJlG98W5tRZK9vG8UqmQ9KZqEsLF80l499aQXx/tbGOR5Yk1+QO2D3mq3YniowdDSnIVOuAT7JQ== X-Received: by 2002:a2e:95c6:0:b0:2b6:da88:a2d0 with SMTP id y6-20020a2e95c6000000b002b6da88a2d0mr1449694ljh.47.1690376822773; Wed, 26 Jul 2023 06:07:02 -0700 (PDT) Received: from [192.168.1.20] ([178.197.223.104]) by smtp.gmail.com with ESMTPSA id r27-20020a17090638db00b009786c8249d6sm9661395ejd.175.2023.07.26.06.07.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 Jul 2023 06:07:02 -0700 (PDT) Message-ID: <33232e22-1014-2670-47f6-712b0acc929d@linaro.org> Date: Wed, 26 Jul 2023 15:07:00 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 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> From: Krzysztof Kozlowski In-Reply-To: <516a54da44724001895f7e50634ad884@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 26/07/2023 14:32, Naveen Kumar Goud Arepalli (QUIC) wrote: > On Tue, Jul 25, 2023 at 03:30:07PM +0530, Naveen Kumar Goud Arepalli wrote: >> L8A is the supply for UFS VCC, UFS specification allows different VCC >> configurations for UFS devices. >> -UFS 2.x devices: 2.70V - 3.60V >> -UFS 3.x devices: 2.40V - 2.70V >> >> As sa8775p-ride supports both ufs 2.x and ufs 3.x devices, remove >> min/max voltages for L8A regulator. Initial voltage of L8A will be set >> to 2.504v or 2.952v during PON depending on the UFS device type. On >> sa8775, UFS is the only client in Linux for L8A and this regulator >> will be voted only for enabling/disabling. >> >> Signed-off-by: Naveen Kumar Goud Arepalli >> --- >> arch/arm64/boot/dts/qcom/sa8775p-ride.dts | 2 -- >> 1 file changed, 2 deletions(-) >> >> 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. >>>>> 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? Best regards, Krzysztof