RE: [PATCH v5 6/8] scsi: ufs: add LU Dedicated buffer mode support for WriteBooster

Avri Altman
2020-05-03T14:27:10Z

> According to UFS specification, there are two WriteBooster mode of
> operations: "LU dedicated buffer" mode and "shared buffer" mode.
> In the "LU dedicated buffer" mode, the WriteBooster Buffer is
> dedicated to a logical unit.
>
> If the device supports the "LU dedicated buffer" mode, this mode is
> configured by setting bWriteBoosterBufferType to 00h. The logical
> unit WriteBooster Buffer size is configured by setting the
> dLUNumWriteBoosterBufferAllocUnits field of the related Unit
> Descriptor. Only a value greater than zero enables the WriteBooster
> feature in the logical unit.
>
> Modify ufshcd_wb_probe() as above description to support LU Dedicated
> buffer mode.
>
> Note that according to UFS 3.1 specification, the valid value of
> bDeviceMaxWriteBoosterLUs parameter in Geometry Descriptor is 1,
> which means at most one LUN can have WriteBooster buffer in "LU
> dedicated buffer mode". Therefore this patch supports only one
> LUN with WriteBooster enabled. All WriteBooster related sysfs nodes
> are specifically mapped to the LUN with WriteBooster enabled in
> LU Dedicated buffer mode.
>
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>