RE: [PATCH 0/3] Add quirk to support exynos ufshci

["Alim Akhtar" <alim.akhtar@samsung.com>]

Hi Jongmin

> -----Original Message-----
> From: jongmin jeong <jjmin.jeong@samsung.com>
> Sent: 27 May 2021 08:39
> To: jejb@linux.ibm.com; martin.petersen@oracle.com
> Cc: alim.akhtar@samsung.com; avri.altman@wdc.com;
> cang@codeaurora.org; beanhuo@micron.com; adrian.hunter@intel.com;
> linux-scsi@vger.kernel.org; linux-kernel@vger.kernel.org;
> jjmin.jeong@samsung.com
> Subject: [PATCH 0/3] Add quirk to support exynos ufshci
> 
> In ExynosAuto(variant of the Exynos for automotive), the UFS Storage needs
> 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.
> 
> 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.
> 
> Below figure is the conception of UFS-IOV architeture.
> 
>     +------+          +------+
>     | OS#1 |          | OS#2 |
>     +------+          +------+
>        |                 |
>  +------------+     +------------+
>  |  Physical  |     |   Virtual  |
>  |    Host    |     |    Host    |
>  +------------+     +------------+
>    |      |              | <-- UTP_CMD_SAP, UTP_TM_SAP
>    |   +-------------------------+
>    |   |    Function Arbitor     |
>    |   +-------------------------+
>  +-------------------------------+
>  |           UTP Layer           |
>  +-------------------------------+
>  +-------------------------------+
>  |           UIC Layer           |
>  +-------------------------------+
> 
> There are two types of host controllers on the UFS host controller that we
> 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).
> 
> 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.
> 
> Since VH can only use less functions than PH, it is necessary to send a request
> 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.
> 
> In this structure, the virtual host can't support some feature and need to 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 host
> reset handler.
> 
> 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
> 
>  drivers/scsi/ufs/ufshcd.c | 13 +++++++++++++  drivers/scsi/ufs/ufshcd.h |
> 18 ++++++++++++++++++
>  2 files changed, 31 insertions(+)
> 
We do not encourage adding QUIRKs without having actual code that sets these 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