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From:   "Alim Akhtar" <alim.akhtar@samsung.com>
To:     "'jongmin jeong'" <jjmin.jeong@samsung.com>, <jejb@linux.ibm.com>,
        <martin.petersen@oracle.com>
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        <linux-kernel@vger.kernel.org>
In-Reply-To: <20210527030901.88403-1-jjmin.jeong@samsung.com>
Subject: RE: [PATCH 0/3] Add quirk to support exynos ufshci
Date:   Thu, 27 May 2021 13:47:05 +0530
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References: <CGME20210527031217epcas2p44b9d999edcc55b345dfd0749acefeaec@epcas2p4.samsung.com>
        <20210527030901.88403-1-jjmin.jeong@samsung.com>
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Hi Jongmin

> -----Original Message-----
> From: jongmin jeong <jjmin.jeong=40samsung.com>
> Sent: 27 May 2021 08:39
> To: jejb=40linux.ibm.com; martin.petersen=40oracle.com
> Cc: alim.akhtar=40samsung.com; avri.altman=40wdc.com;
> cang=40codeaurora.org; beanhuo=40micron.com; adrian.hunter=40intel.com;
> linux-scsi=40vger.kernel.org; linux-kernel=40vger.kernel.org;
> jjmin.jeong=40samsung.com
> Subject: =5BPATCH 0/3=5D Add quirk to support exynos ufshci
>=20
> In ExynosAuto(variant of the Exynos for automotive), the UFS Storage need=
s
> to be accessed from multi-OS.
> To increase IO performance and reduce SW complexity, we implemented
> UFS-IOV to support storage IO virtualization feature on UFS.
>=20
> IO virtualization increases IO performance and reduce SW complexity with
> small area cost. And IO virtualization supports virtual machine isolation=
 for
> Security and Safety which are requested by Multi-OS system such as
> automotive application.
>=20
> Below figure is the conception of UFS-IOV architeture.
>=20
>     +------+          +------+
>     =7C OS=231 =7C          =7C OS=232 =7C
>     +------+          +------+
>        =7C                 =7C
>  +------------+     +------------+
>  =7C  Physical  =7C     =7C   Virtual  =7C
>  =7C    Host    =7C     =7C    Host    =7C
>  +------------+     +------------+
>    =7C      =7C              =7C <-- UTP_CMD_SAP, UTP_TM_SAP
>    =7C   +-------------------------+
>    =7C   =7C    Function Arbitor     =7C
>    =7C   +-------------------------+
>  +-------------------------------+
>  =7C           UTP Layer           =7C
>  +-------------------------------+
>  +-------------------------------+
>  =7C           UIC Layer           =7C
>  +-------------------------------+
>=20
> There are two types of host controllers on the UFS host controller that w=
e
> designed.
> The UFS device has a Function Arbitor that arranges commands of each host=
.
> When each host transmits a command to the Arbitor, the Arbitor transmits =
it
> to the UTP layer.
> Physical Host(PH) support all UFSHCI functions(all SAPs) same as
> conventional UFSHCI.
> Virtual Host(VH) support only data transfer function(UTP_CMD_SAP and
> UTP_TM_SAP).
>=20
> In an environment where multiple OSs are used, the OS that has the
> leadership of the system is called System OS. This system OS uses PH and
> controls error handling.
>=20
> Since VH can only use less functions than PH, it is necessary to send a r=
equest
> to PH for Detected Error Handling in VH. To interface among PH and VHs,
> UFSHCI HW supports mailbox. PH can broadcast mail to other VH at the same
> time with arguments and VH can mail to PH with arguments.
> PH and VH generate interrupts when mails from PH or VH.
>=20
> In this structure, the virtual host can't support some feature and need t=
o skip
> the some part of ufshcd code by using quirk.
> This patchs add quirks so that the UIC command is ignored and the ufshcd =
init
> process can be skipped for VH. Also, according to our UFS-IOV policy, we
> added a quirk to the abort handler or device reset handler to call the ho=
st
> reset handler.
>=20
> jongmin jeong (3):
>   scsi: ufs: add quirk to handle broken UIC command
>   scsi: ufs: add quirk to enable host controller without interface
>     configuration
>   scsi: ufs: add quirk to support host reset only
>=20
>  drivers/scsi/ufs/ufshcd.c =7C 13 +++++++++++++  drivers/scsi/ufs/ufshcd.=
h =7C
> 18 ++++++++++++++++++
>  2 files changed, 31 insertions(+)
>=20
We do not encourage adding QUIRKs without having actual code that sets thes=
e quirks, so that we understand how these are actually getting used.
So better you post the all the changes, not just quirks.
> --
> 2.31.1