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;
IronPort-SDR: nVlAcVRZjvj3gwmUMAZTPgKidJIpnjZocU2uXPk/GuVVe1oNwBbjA3FHTzX6YF+VdZ2e6zFpUg
 EgknvMid/g02GAkZSsIjmkJ6gim6wZNaGfl9ullFoZ6b9WiQpPOTSyDqmqSv8TkeF2izWVwNxD
 nnndbFAAVXOxv/Acu/03tHN1jwFM/0bfB0+1c1IKys3Xn643x1BtkU7l+Ab5KslPjPX+UxMBA8
 lLZdMqnVb94E+uqs2ZozbsndqPFbu23Hr/G8DA/O2QhtPLhvNJYZL3M54A7M3aOr5yHPIj8SYS
 C7E=
From:   Avri Altman <Avri.Altman@wdc.com>
To:     Stanley Chu <stanley.chu@mediatek.com>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "alim.akhtar@samsung.com" <alim.akhtar@samsung.com>,
        "jejb@linux.ibm.com" <jejb@linux.ibm.com>
CC:     "beanhuo@micron.com" <beanhuo@micron.com>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
        "cang@codeaurora.org" <cang@codeaurora.org>,
        "matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
        "bvanassche@acm.org" <bvanassche@acm.org>,
        "linux-mediatek@lists.infradead.org" 
        <linux-mediatek@lists.infradead.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "nguyenb@codeaurora.org" <nguyenb@codeaurora.org>,
        "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "kuohong.wang@mediatek.com" <kuohong.wang@mediatek.com>,
        "peter.wang@mediatek.com" <peter.wang@mediatek.com>,
        "chun-hung.wu@mediatek.com" <chun-hung.wu@mediatek.com>,
        "andy.teng@mediatek.com" <andy.teng@mediatek.com>,
        "chaotian.jing@mediatek.com" <chaotian.jing@mediatek.com>,
        "cc.chou@mediatek.com" <cc.chou@mediatek.com>,
        "jiajie.hao@mediatek.com" <jiajie.hao@mediatek.com>,
        "alice.chao@mediatek.com" <alice.chao@mediatek.com>
Subject: RE: [PATCH v2] scsi: ufs: Remove pre-defined initial voltage values
 of device powers
Thread-Topic: [PATCH v2] scsi: ufs: Remove pre-defined initial voltage values
 of device powers
Thread-Index: AQHWx65onxXE/o6nwEmQABYecW9/fKnhz+9A
Date:   Tue, 1 Dec 2020 07:01:23 +0000
Message-ID: <DM6PR04MB6575D146BBE580B0EF1F995EFCF40@DM6PR04MB6575.namprd04.prod.outlook.com>
References: <20201201065114.1001-1-stanley.chu@mediatek.com>
In-Reply-To: <20201201065114.1001-1-stanley.chu@mediatek.com>
Accept-Language: en-US
Content-Language: en-US
wdcipoutbound: EOP-TRUE
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 5336c9b3-b5ec-4c30-4319-08d895c6e9fc
X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Dec 2020 07:01:23.3795
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: rE0QYkk3ue8qX5NQR0XEuqagc5uf8/tEtrfXEK45DCeZFEd11QmdNRoQ3xIlHmEJGP4sSAcKcfsTQCTw27q00g==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR04MB6140
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

>=20
> UFS specficication allows different VCC configurations for UFS devices,
> for example,
>         (1). 2.70V - 3.60V (Activated by default in UFS core driver)
>         (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)
>=20
> With the introduction of UFS 3.x products, an issue is happening that
> UFS driver will use wrong "min_uV-max_uV" values to configure the
> voltage of VCC regulator on UFU 3.x products with the configuration (3)
> used.
>=20
> To solve this issue, we simply remove pre-defined initial VCC voltage
> values in UFS core driver with below reasons,
>=20
> 1. UFS specifications do not define how to detect the VCC configuration
>    supported by attached device.
>=20
> 2. Device tree already supports standard regulator properties.
>=20
> Therefore VCC voltage shall be defined correctly in device tree, and
> shall not changed by UFS driver. What UFS driver needs to do is simply
> enable or disable the VCC regulator only.
>=20
> Similar change is applied to VCCQ and VCCQ2 as well.
>=20
> Note that we keep struct ufs_vreg unchanged. This is allow vendors to
> configure proper min_uV and max_uV of any regulators to make
> regulator_set_voltage() works during regulator toggling flow.
> Without specific vendor configurations, min_uV and max_uV will be NULL
> by default and UFS core driver will enable or disable the regulator
> only without adjusting its voltage.
>=20
> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Acked-by: Avri Altman <avri.altman@wdc.com>