linux-kernel - RE: [PATCH v4 4/4] scsi: ufs: add compatibility with 3.1 UFS unit descriptor length

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Message-ID: <SN6PR04MB46404D5B77121B367C17AEA2FC8C0@SN6PR04MB4640.namprd04.prod.outlook.com>
Date:   Sat, 30 May 2020 06:56:37 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Bean Huo <huobean@...il.com>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "beanhuo@...ron.com" <beanhuo@...ron.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "tomas.winkler@...el.com" <tomas.winkler@...el.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>
CC:     "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4 4/4] scsi: ufs: add compatibility with 3.1 UFS unit
 descriptor length

 
> 
> From: Bean Huo <beanhuo@...ron.com>
> 
> For UFS 3.1, the normal unit descriptor is 10 bytes larger
> than the RPMB unit, however, both descriptors share the same
> desc_idn, to cover both unit descriptors with one length, we
> choose the normal unit descriptor length by desc_index.
This is not what your code is doing.
For RPMB - desc size will not be 0x2d but remain 256.

Your strategy is still correct IMO - if you assign the larger size,
The device will not reply with error, but with the proper buffer.

You can also rely that reading the rpmb unit descriptor will not happen before
Reading regular luns, because this is happening in the first slave_alloc.
 
Hence, I think you can drop the extra if, and just add the comment.

Thanks,
Avri 

> 
> Signed-off-by: Bean Huo <beanhuo@...ron.com>
> ---
>  drivers/scsi/ufs/ufs.h    |  1 +
>  drivers/scsi/ufs/ufshcd.c | 11 ++++++++---
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
> index 6548ef102eb9..332ae09e6238 100644
> --- a/drivers/scsi/ufs/ufs.h
> +++ b/drivers/scsi/ufs/ufs.h
> @@ -63,6 +63,7 @@
>  #define UFS_UPIU_MAX_UNIT_NUM_ID       0x7F
>  #define UFS_MAX_LUNS           (SCSI_W_LUN_BASE +
> UFS_UPIU_MAX_UNIT_NUM_ID)
>  #define UFS_UPIU_WLUN_ID       (1 << 7)
> +#define UFS_RPMB_UNIT          0xC4
> 
>  /* WriteBooster buffer is available only for the logical unit from 0 to 7 */
>  #define UFS_UPIU_MAX_WB_LUN_ID 8
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 951e52babf65..3cdc585d0095 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -3070,11 +3070,16 @@ void ufshcd_map_desc_id_to_length(struct
> ufs_hba *hba, enum desc_idn desc_id,
>  EXPORT_SYMBOL(ufshcd_map_desc_id_to_length);
> 
>  static void ufshcd_update_desc_length(struct ufs_hba *hba,
> -                                     enum desc_idn desc_id,
> +                                     enum desc_idn desc_id, int desc_index,
>                                       unsigned char desc_len)
>  {
>         if (hba->desc_size[desc_id] == QUERY_DESC_MAX_SIZE &&
> -           desc_id != QUERY_DESC_IDN_STRING)
> +           desc_id != QUERY_DESC_IDN_STRING && desc_index !=
> UFS_RPMB_UNIT)
> +               /* For UFS 3.1, the normal unit descriptor is 10 bytes larger
> +                * than the RPMB unit, however, both descriptors share the same
> +                * desc_idn, to cover both unit descriptors with one length, we
> +                * choose the normal unit descriptor length by desc_index.
> +                */
>                 hba->desc_size[desc_id] = desc_len;
>  }
> 
> @@ -3141,7 +3146,7 @@ int ufshcd_read_desc_param(struct ufs_hba *hba,
>                 goto out;
>         }
> 
> -       ufshcd_update_desc_length(hba, desc_id,
> +       ufshcd_update_desc_length(hba, desc_id, desc_index,
>                                   desc_buf[QUERY_DESC_LENGTH_OFFSET]);
> 
>         /* Check wherher we will not copy more data, than available */
> --
> 2.17.1