Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
IronPort-SDR: u6ND7yk97Jawc4pIbDZFI33TpyG/X+1jutlTa7kioOm43gwm+w0jniogSKxFpYN+faG1otxoe8
 QvIPzzNEGvPs7ccQYhb79Eou+s+jo/hA9bSy+9ir7giEtG1bZqh/poPu6OTqhGHUDqkkJXhDkO
 Ju1rEOXaKV3mX9SAotnYQUKF2fZS1hVrgLP9FgaORK2hxH9L7myCaEwaQ9CkbjfJDmfTm3iK55
 FuR8jfPn+OwVlN/apDyKoeuq5q6lQG+JgC0KDb2qNZlTg9IbgTv1odHxiehKXmLF+GqjEisVOZ
 LnU=
From:   Avri Altman <Avri.Altman@wdc.com>
To:     Can Guo <cang@codeaurora.org>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
        "nguyenb@codeaurora.org" <nguyenb@codeaurora.org>,
        "hongwus@codeaurora.org" <hongwus@codeaurora.org>,
        "rnayak@codeaurora.org" <rnayak@codeaurora.org>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "kernel-team@android.com" <kernel-team@android.com>,
        "saravanak@google.com" <saravanak@google.com>,
        "salyzyn@google.com" <salyzyn@google.com>
CC:     Alim Akhtar <alim.akhtar@samsung.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Bean Huo <beanhuo@micron.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Venkat Gopalakrishnan <venkatg@codeaurora.org>,
        Tomas Winkler <tomas.winkler@intel.com>,
        open list <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v3 1/1] scsi: ufs: Enable block layer runtime PM for
 well-known logical units
Thread-Topic: [PATCH v3 1/1] scsi: ufs: Enable block layer runtime PM for
 well-known logical units
Thread-Index: AQHWApnW8d/lojckW0+fOnV7WNzy26hZ8Txw
Date:   Wed, 25 Mar 2020 23:18:59 +0000
Message-ID: <SN6PR04MB464005D38551AFBCBBA72E2BFCCE0@SN6PR04MB4640.namprd04.prod.outlook.com>
References: <1585136153-24852-1-git-send-email-cang@codeaurora.org>
In-Reply-To: <1585136153-24852-1-git-send-email-cang@codeaurora.org>
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: 086dd241-ce40-4bda-9d89-08d7d112e5eb
X-MS-Exchange-CrossTenant-originalarrivaltime: 25 Mar 2020 23:18:59.1503
 (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: Qw6R05iSUujVU4q0RtLd4qMc/863z7h/iPYkDI+Gj7lA3/tIW91ghxvcE1/ap6blIUEN9ivOw+d/2xbKbVmG0w==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR04MB4446
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

=20
>=20
> Block layer RPM is enabled for the genernal UFS SCSI devices when they ar=
e
> probed by their driver. However block layer RPM is not enabled for UFS
> well-known SCSI devices.
>=20
> As UFS SCSI devices have their corresponding BSG char devices, accessing
> a BSG char device via IOCTL may send requests to its corresponding SCSI
> device through its request queue. If BSG IOCTL sends a request to a
> well-known SCSI device when hba is not runtime active, due to block layer
> RPM is not eanbled for the well-known SCSI devices, hba, which is at the
> top of a scsi device's parent chain, shall not be resumed, then unexpecte=
d
> error would happen.
>=20
> This change enables block layer RPM for the well-known SCSI devices, so
> that block layer can handle RPM for the well-known SCSI devices just like
> for the general SCSI devices.
>=20
> Signed-off-by: Can Guo <cang@codeaurora.org>
Reviewed-by: Avri Altman <avri.altman@wdc.com>