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[104.57.184.186]) by smtp.gmail.com with ESMTPSA id e5sm9218917otl.75.2020.11.30.15.14.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Nov 2020 15:14:39 -0800 (PST) Date: Mon, 30 Nov 2020 17:14:37 -0600 From: Bjorn Andersson To: "Asutosh Das (asd)" Cc: 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, cang@codeaurora.org, 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 Message-ID: References: <20201130091610.2752-1-stanley.chu@mediatek.com> <568660cd-80e6-1b8f-d426-4614c9159ff4@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <568660cd-80e6-1b8f-d426-4614c9159ff4@codeaurora.org> Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org 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