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From:   Avri Altman <Avri.Altman@wdc.com>
To:     Stanley Chu <stanley.chu@mediatek.com>,
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Subject: RE: [PATCH v4 6/8] scsi: ufs: add LU Dedicated buffer mode support
 for WriteBooster
Thread-Topic: [PATCH v4 6/8] scsi: ufs: add LU Dedicated buffer mode support
 for WriteBooster
Thread-Index: AQHWIRCrXRqrbU2HS02FXUAKk3v6OKiV+eag
Date:   Sun, 3 May 2020 08:00:13 +0000
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References: <20200503060351.10572-1-stanley.chu@mediatek.com>
 <20200503060351.10572-7-stanley.chu@mediatek.com>
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> -       if (!(hba->dev_info.b_wb_buffer_type &&
> -             hba->dev_info.d_wb_alloc_units))
> -               goto wb_disabled;
> +       if (hba->dev_info.b_wb_buffer_type =3D=3D WB_BUF_MODE_SHARED) {
> +               hba->dev_info.d_wb_alloc_units =3D
> +               get_unaligned_be32(desc_buf +
> +                                  DEVICE_DESC_PARAM_WB_SHARED_ALLOC_UNIT=
S);
> +               if (!hba->dev_info.d_wb_alloc_units)
> +                       goto wb_disabled;
> +       } else {
> +               for (lun =3D 0; lun < hba->dev_info.max_lu_supported; lun=
++) {
max_lu_supported is determined according to bMaxNumberLU in the geometry de=
scriptor,
which can be 32. WB buffer however, is only valid only for LU 0, ..., LU7.
Better to add this new limit to ufs.h.

> +                       ret =3D ufshcd_read_unit_desc_param(hba,
> +                                       lun,
> +                                       UNIT_DESC_PARAM_WB_BUF_ALLOC_UNIT=
S,
> +                                       (u8 *)&d_lu_wb_buf_alloc,
> +                                       sizeof(d_lu_wb_buf_alloc));
> +                       if (ret)
> +                               goto wb_disabled;
I think you should just continue here, as it is ok for the query to fail.
The spec says:
The WriteBooster Buffer is available only for the logical units from 0 to 7=
 which are configured as
"normal memory type" (bMemoryType =3D 00h) and "not Boot well known logical=
 unit" (bBootLunID =3D
00h), otherwise the Query Request shall fail and the Query Response field s=
hall be set to "General
Failure".

Sorry for not noticing this earlier.

Thanks,
Avri
> +                       if (d_lu_wb_buf_alloc) {
> +                               hba->dev_info.wb_dedicated_lu =3D lun;
> +                               break;
> +                       }
> +               }
>=20
> +               if (!d_lu_wb_buf_alloc)
> +                       goto wb_disabled;
> +       }
>         return;
>=20
>  wb_disabled:
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 898883058e3a..f232a67fd9b3 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -861,6 +861,13 @@ static inline bool
> ufshcd_keep_autobkops_enabled_except_suspend(
>         return hba->caps &
> UFSHCD_CAP_KEEP_AUTO_BKOPS_ENABLED_EXCEPT_SUSPEND;
>  }
>=20
> +static inline u8 ufshcd_wb_get_flag_index(struct ufs_hba *hba)
> +{
> +       if (hba->dev_info.b_wb_buffer_type =3D=3D
> WB_BUF_MODE_LU_DEDICATED)
> +               return hba->dev_info.wb_dedicated_lu;
> +       return 0;
> +}
> +
>  extern int ufshcd_runtime_suspend(struct ufs_hba *hba);
>  extern int ufshcd_runtime_resume(struct ufs_hba *hba);
>  extern int ufshcd_runtime_idle(struct ufs_hba *hba);
> --
> 2.18.0