Re: Subject: [PATCH v14 1/3] scsi: ufs: Introduce HPB feature

[Stanley Chu]

Hi Daejun,

On Wed, 2020-12-16 at 11:45 +0900, Daejun Park wrote:
> This is a patch for the HPB initialization and adds HPB function calls to
> UFS core driver.
> 
> NAND flash-based storage devices, including UFS, have mechanisms to
> translate logical addresses of IO requests to the corresponding physical
> addresses of the flash storage.
> In UFS, Logical-address-to-Physical-address (L2P) map data, which is
> required to identify the physical address for the requested IOs, can only
> be partially stored in SRAM from NAND flash. Due to this partial loading,
> accessing the flash address area where the L2P information for that address
> is not loaded in the SRAM can result in serious performance degradation.
> 
> The basic concept of HPB is to cache L2P mapping entries in host system
> memory so that both physical block address (PBA) and logical block address
> (LBA) can be delivered in HPB read command.
> The HPB READ command allows to read data faster than a read command in UFS
> since it provides the physical address (HPB Entry) of the desired logical
> block in addition to its logical address. The UFS device can access the
> physical block in NAND directly without searching and uploading L2P mapping
> table. This improves read performance because the NAND read operation for
> uploading L2P mapping table is removed.
> 
> In HPB initialization, the host checks if the UFS device supports HPB
> feature and retrieves related device capabilities. Then, some HPB
> parameters are configured in the device.
> 
> Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
> Reviewed-by: Can Guo <cang@xxxxxxxxxxxxxx>
> Acked-by: Avri Altman <Avri.Altman@xxxxxxx>
> Tested-by: Bean Huo <beanhuo@xxxxxxxxxx>
> Signed-off-by: Daejun Park <daejun7.park@xxxxxxxxxxx>
> ---
>  Documentation/ABI/testing/sysfs-driver-ufs |  80 +++
>  drivers/scsi/ufs/Kconfig                   |   9 +
>  drivers/scsi/ufs/Makefile                  |   1 +
>  drivers/scsi/ufs/ufs-sysfs.c               |  18 +
>  drivers/scsi/ufs/ufs.h                     |  13 +
>  drivers/scsi/ufs/ufshcd.c                  |  48 ++
>  drivers/scsi/ufs/ufshcd.h                  |  23 +-
>  drivers/scsi/ufs/ufshpb.c                  | 562 +++++++++++++++++++++
>  drivers/scsi/ufs/ufshpb.h                  | 167 ++++++
>  9 files changed, 920 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/scsi/ufs/ufshpb.c
>  create mode 100644 drivers/scsi/ufs/ufshpb.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-driver-ufs b/Documentation/ABI/testing/sysfs-driver-ufs
> index d1a352194d2e..8b16a353392c 100644
> --- a/Documentation/ABI/testing/sysfs-driver-ufs
> +++ b/Documentation/ABI/testing/sysfs-driver-ufs
> @@ -1019,3 +1019,83 @@ Contact:	Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
>  Description:	This entry shows the configured size of WriteBooster buffer.
>  		0400h corresponds to 4GB.
>  		The file is read only.
> +
> +What:		/sys/bus/platform/drivers/ufshcd/*/device_descriptor/hpb_version
> +Date:		December 2020
> +Contact:	Daejun Park <daejun7.park@xxxxxxxxxxx>
> +Description:	This entry shows the HPB specification version.
> +		The full information about the descriptor could be found at UFS
> +		HPB (Host Performance Booster) Extension specifications.
> +		Example: version 1.2.3 = 0123h
> +		The file is read only.
> +
> +What:		/sys/bus/platform/drivers/ufshcd/*/device_descriptor/hpb_control
> +Date:		December 2020
> +Contact:	Daejun Park <daejun7.park@xxxxxxxxxxx>
> +Description:	This entry shows an indication of the HPB control mode.
> +		00h: Host control mode
> +		01h: Device control mode
> +		The file is read only.
> +
> +What:		/sys/bus/platform/drivers/ufshcd/*/geometry_descriptor/hpb_region_size
> +Date:		December 2020
> +Contact:	Daejun Park <daejun7.park@xxxxxxxxxxx>
> +Description:	This entry shows the bHPBRegionSize which can be calculated
> +		as in the following (in bytes):
> +		HPB Region size = 512B * 2^bHPBRegionSize
> +		The file is read only.
> +
> +What:		/sys/bus/platform/drivers/ufshcd/*/geometry_descriptor/hpb_number_lu
> +Date:		December 2020
> +Contact:	Daejun Park <daejun7.park@xxxxxxxxxxx>
> +Description:	This entry shows the maximum number of HPB LU supported	by
> +		the device.
> +		00h: HPB is not supported by the device.
> +		01h ~ 20h: Maximum number of HPB LU supported by the device
> +		The file is read only.
> +
> +What:		/sys/bus/platform/drivers/ufshcd/*/geometry_descriptor/hpb_number_lu
> +Date:		December 2020
> +Contact:	Daejun Park <daejun7.park@xxxxxxxxxxx>
> +Description:	This entry shows the maximum number of HPB LU supported	by
> +		the device.
> +		00h: HPB is not supported by the device.
> +		01h ~ 20h: Maximum number of HPB LU supported by the device
> +		The file is read only.

Please remove above duplicated item.

Thanks,
Stanley Chu