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[23.128.96.18]) by mx.google.com with ESMTP id dt1si246936ejc.558.2020.11.30.21.08.47; Mon, 30 Nov 2020 21:09:09 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@mg.codeaurora.org header.s=smtp header.b=uFBlTyer; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727694AbgLAD37 (ORCPT + 99 others); Mon, 30 Nov 2020 22:29:59 -0500 Received: from m42-4.mailgun.net ([69.72.42.4]:25505 "EHLO m42-4.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726841AbgLAD37 (ORCPT ); Mon, 30 Nov 2020 22:29:59 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1606793373; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=3e5O5WzuaYMeaQ05gvvQ0q7C+TOB0SwgYc2NPdP+STo=; b=uFBlTyerJaSEtVrVojQKBn4eCD+sVR6jxCuYmP0cHj2nTEmCuGexGpNtnrsUBcAlpNBF7jRB ofawV0huJRy/QZXaQwJwFNHc3a5KE9doKjYW6w8pgHWFIlMNIGEG6lEUMPPywl/cYGN3cA3d NZ0enpREUkNSobar5NFkbzw0ZZw= X-Mailgun-Sending-Ip: 69.72.42.4 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n03.prod.us-east-1.postgun.com with SMTP id 5fc5b89c51762b1886534495 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 01 Dec 2020 03:29:32 GMT Sender: cang=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id D637DC43463; Tue, 1 Dec 2020 03:29:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-caf-mail-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=ALL_TRUSTED,BAYES_00, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: cang) by smtp.codeaurora.org (Postfix) with ESMTPSA id 44E0AC433C6; Tue, 1 Dec 2020 03:29:29 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 01 Dec 2020 11:29:29 +0800 From: Can Guo To: "Asutosh Das (asd)" Cc: Bjorn Andersson , Stanley Chu , linux-scsi@vger.kernel.org, martin.petersen@oracle.com, avri.altman@wdc.com, alim.akhtar@samsung.com, jejb@linux.ibm.com, beanhuo@micron.com, matthias.bgg@gmail.com, bvanassche@acm.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, nguyenb@codeaurora.org, kuohong.wang@mediatek.com, peter.wang@mediatek.com, chun-hung.wu@mediatek.com, andy.teng@mediatek.com, chaotian.jing@mediatek.com, cc.chou@mediatek.com, jiajie.hao@mediatek.com, alice.chao@mediatek.com Subject: Re: [RFC PATCH v1] scsi: ufs: Remove pre-defined initial VCC voltage values In-Reply-To: References: <20201130091610.2752-1-stanley.chu@mediatek.com> <568660cd-80e6-1b8f-d426-4614c9159ff4@codeaurora.org> <4335d590-0506-d920-8e7f-f0f0372780f9@codeaurora.org> Message-ID: X-Sender: cang@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-12-01 11:19, Asutosh Das (asd) wrote: > On 11/30/2020 6:53 PM, Bjorn Andersson wrote: >> On Mon 30 Nov 17:54 CST 2020, Asutosh Das (asd) wrote: >> >>> On 11/30/2020 3:14 PM, Bjorn Andersson wrote: >>>> On Mon 30 Nov 16:51 CST 2020, Asutosh Das (asd) wrote: >>>> >>>>> On 11/30/2020 1:16 AM, Stanley Chu wrote: >>>>>> UFS specficication allows different VCC configurations for UFS >>>>>> devices, >>>>>> for example, >>>>>> (1). 2.70V - 3.60V (By default) >>>>>> (2). 1.70V - 1.95V (Activated if "vcc-supply-1p8" is declared in >>>>>> device tree) >>>>>> (3). 2.40V - 2.70V (Supported since UFS 3.x) >>>>>> >>>>>> With the introduction of UFS 3.x products, an issue is happening >>>>>> that >>>>>> UFS driver will use wrong "min_uV/max_uV" configuration to toggle >>>>>> VCC >>>>>> regulator on UFU 3.x products with VCC configuration (3) used. >>>>>> >>>>>> To solve this issue, we simply remove pre-defined initial VCC >>>>>> voltage >>>>>> values in UFS driver with below reasons, >>>>>> >>>>>> 1. UFS specifications do not define how to detect the VCC >>>>>> configuration >>>>>> supported by attached device. >>>>>> >>>>>> 2. Device tree already supports standard regulator properties. >>>>>> >>>>>> Therefore VCC voltage shall be defined correctly in device tree, >>>>>> and >>>>>> shall not be changed by UFS driver. What UFS driver needs to do is >>>>>> simply >>>>>> enabling or disabling the VCC regulator only. >>>>>> >>>>>> This is a RFC conceptional patch. Please help review this and feel >>>>>> free to feedback any ideas. Once this concept is accepted, and >>>>>> then >>>>>> I would post a more completed patch series to fix this issue. >>>>>> >>>>>> Signed-off-by: Stanley Chu >>>>>> --- >>>>>> drivers/scsi/ufs/ufshcd-pltfrm.c | 10 +--------- >>>>>> 1 file changed, 1 insertion(+), 9 deletions(-) >>>>>> >>>>>> diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c >>>>>> b/drivers/scsi/ufs/ufshcd-pltfrm.c >>>>>> index a6f76399b3ae..3965be03c136 100644 >>>>>> --- a/drivers/scsi/ufs/ufshcd-pltfrm.c >>>>>> +++ b/drivers/scsi/ufs/ufshcd-pltfrm.c >>>>>> @@ -133,15 +133,7 @@ static int ufshcd_populate_vreg(struct device >>>>>> *dev, const char *name, >>>>>> vreg->max_uA = 0; >>>>>> } >>>>>> - if (!strcmp(name, "vcc")) { >>>>>> - if (of_property_read_bool(np, "vcc-supply-1p8")) { >>>>>> - vreg->min_uV = UFS_VREG_VCC_1P8_MIN_UV; >>>>>> - vreg->max_uV = UFS_VREG_VCC_1P8_MAX_UV; >>>>>> - } else { >>>>>> - vreg->min_uV = UFS_VREG_VCC_MIN_UV; >>>>>> - vreg->max_uV = UFS_VREG_VCC_MAX_UV; >>>>>> - } >>>>>> - } else if (!strcmp(name, "vccq")) { >>>>>> + if (!strcmp(name, "vccq")) { >>>>>> vreg->min_uV = UFS_VREG_VCCQ_MIN_UV; >>>>>> vreg->max_uV = UFS_VREG_VCCQ_MAX_UV; >>>>>> } else if (!strcmp(name, "vccq2")) { >>>>>> >>>>> >>>>> Hi Stanley >>>>> >>>>> Thanks for the patch. Bao (nguyenb) was also working towards >>>>> something >>>>> similar. >>>>> Would it be possible for you to take into account the scenario in >>>>> which the >>>>> same platform supports both 2.x and 3.x UFS devices? >>>>> >>>>> These've different voltage requirements, 2.4v-3.6v. >>>>> I'm not sure if standard dts regulator properties can support this. >>>>> >>>> >>>> What is the actual voltage requirement for these devices and how >>>> does >>>> the software know what voltage to pick in this range? >>>> >>>> Regards, >>>> Bjorn >>>> >>>>> -asd >>>>> >>>>> >>>>> -- The Qualcomm Innovation Center, Inc. is a member of the Code >>>>> Aurora Forum, >>>>> Linux Foundation Collaborative Project >>> >>> For platforms that support both 2.x (2.7v-3.6v) and 3.x (2.4v-2.7v), >>> the >>> voltage requirements (Vcc) are 2.4v-3.6v. The software initializes >>> the ufs >>> device at 2.95v & reads the version and if the device is 3.x, it may >>> do the >>> following: >>> - Set the device power mode to SLEEP >>> - Disable the Vcc >>> - Enable the Vcc and set it to 2.5v >>> - Set the device power mode to ACTIVE >>> >>> All of the above may be done at HS-G1 & moved to max supported gear >>> based on >>> the device version, perhaps? >>> >>> Am open to other ideas though. >>> >> >> But that means that for a board where we don't know (don't want to >> know) >> if we have a 2.x or 3.x device we need to set: >> >> regulator-min-microvolt = <2.4V> >> regulator-max-microvolt = <3.6V> >> >> And the 2.5V and the two ranges should be hard coded into the ufshcd >> (in >> particular if they come from the specification). >> >> For devices with only 2.x or 3.x devices, >> regulator-{min,max}-microvolt >> should be adjusted accordingly. >> >> Note that driving the regulators outside these ranges will either >> damage >> the hardware or cause it to misbehave, so these values should be >> defined >> in the board.dts anyways. >> >> Also note that regulator_set_voltage(2.4V, 3.6V) won't give you "a >> voltage between 2.4V and 3.6V, it will most likely give either 2.4V or >> any more specific voltage that we've specified in the board file >> because >> the regulator happens to be shared with some other consumer and >> changing >> it in runtime would be bad. >> >> Regards, >> Bjorn >> > > Understood. > I also understand that assumptions on the regulator limits in the > driver is a bad idea. I'm not sure how it's designed, but I should > think the power-grid design should take care of regulator sharing; if > it's being shared and the platform supports both 2.x and 3.x. Perhaps, > such platforms be identified using a dts flag - not sure if that's > such a good idea though. > > I like Stanley's proposal of a vops and let vendors handle it, until > specs or someone has a better suggestion. Agree, vops is all we need as of now, please upload a change to add one properly. Thanks, Can Guo. > > -asd