Date:   Tue, 25 Feb 2020 12:50:36 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Asutosh Das <asutoshd@...eaurora.org>,
        "subhashj@...eaurora.org" <subhashj@...eaurora.org>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "rnayak@...eaurora.org" <rnayak@...eaurora.org>,
        "vinholikatti@...il.com" <vinholikatti@...il.com>,
        "jejb@...ux.vnet.ibm.com" <jejb@...ux.vnet.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>
CC:     "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Tomas Winkler <tomas.winkler@...el.com>,
        Colin Ian King <colin.king@...onical.com>,
        Bart Van Assche <bvanassche@....org>,
        Venkat Gopalakrishnan <venkatg@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: RE: [<RFC PATCH v1> 1/2] scsi: ufs: add write booster feature support

> +/*
> + * ufshcd_get_wb_alloc_units - returns
> "dLUNumWriteBoosterBufferAllocUnits"
> + * @hba: per-adapter instance
> + * @lun: UFS device lun id
> + * @d_lun_wbb_au: pointer to buffer to hold the LU's alloc units info
> + *
> + * Returns 0 in case of success and d_lun_wbb_au would be returned
> + * Returns -ENOTSUPP if reading d_lun_wbb_au is not supported.
> + * Returns -EINVAL in case of invalid parameters passed to this function.
> + */
> +static int ufshcd_get_wb_alloc_units(struct ufs_hba *hba,
> +                           u8 lun,
> +                           u8 *d_lun_wbb_au)
> +{
> +       int ret;
> +
> +       if (!d_lun_wbb_au)
> +               ret = -EINVAL;
> +
> +       /* WB can be supported only from LU0..LU7 */
> +       else if (lun >= UFS_UPIU_MAX_GENERAL_LUN)
> +               ret = -ENOTSUPP;
> +       else
> +               ret = ufshcd_read_unit_desc_param(hba,
> +                                         lun,
> +                                         UNIT_DESC_PARAM_WB_BUF_ALLOC_UNITS,
> +                                         d_lun_wbb_au,
> +                                         sizeof(*d_lun_wbb_au));
You are reading here a single byte, instead of 4

> +       return ret;
> +}
> +
>  /**
>   * ufshcd_get_lu_power_on_wp_status - get LU's power on write protect
>   * status
> @@ -5194,6 +5267,165 @@ static void
> ufshcd_bkops_exception_event_handler(struct ufs_hba *hba)
>                                 __func__, err);
>  }
> 
> +static bool ufshcd_wb_sup(struct ufs_hba *hba)
> +{
> +       return ((hba->dev_info.d_ext_ufs_feature_sup &
> +                  UFS_DEV_WRITE_BOOSTER_SUP) &&
Don't you want to have a vendor cap as well,
to allow the platform vendor to control this feature?

> +                 (hba->dev_info.b_wb_buffer_type
> +                  || hba->dev_info.wb_config_lun));
> +}
> +
> +



> +static bool ufshcd_wb_is_buf_flush_needed(struct ufs_hba *hba)
> +{
> +       int ret;
> +       u32 cur_buf, status, avail_buf;
> +
> +       if (!ufshcd_wb_sup(hba))
> +               return false;
> +
> +       ret = ufshcd_query_attr_retry(hba,
> UPIU_QUERY_OPCODE_READ_ATTR,
> +                                     QUERY_ATTR_IDN_AVAIL_WB_BUFF_SIZE,
> +                                     0, 0, &avail_buf);
> +       if (ret) {
> +               dev_warn(hba->dev, "%s dAvailableWriteBoosterBufferSize read
> failed %d\n",
> +                        __func__, ret);
> +               return false;
> +       }
> +
> +       ret = ufshcd_vops_get_user_cap_mode(hba);
> +       if (ret <= 0) {
> +               dev_dbg(hba->dev, "Get user-cap reduction mode: failed: %d\n",
> +                       ret);
> +               /* Most commonly used */
> +               ret = UFS_WB_BUFF_PRESERVE_USER_SPACE;
> +       }
> +
> +       hba->dev_info.keep_vcc_on = false;
> +       if (ret == UFS_WB_BUFF_USER_SPACE_RED_EN) {
> +               if (avail_buf <= UFS_WB_10_PERCENT_BUF_REMAIN) {
> +                       hba->dev_info.keep_vcc_on = true;
> +                       return true;
> +               }
> +               return false;
> +       } else if (ret == UFS_WB_BUFF_PRESERVE_USER_SPACE) {
> +               ret = ufshcd_query_attr_retry(hba,
> UPIU_QUERY_OPCODE_READ_ATTR,
> +                                             QUERY_ATTR_IDN_CURR_WB_BUFF_SIZE,
> +                                             0, 0, &cur_buf);
> +               if (ret) {
> +                       dev_err(hba->dev, "%s dCurWriteBoosterBufferSize read failed
> %d\n",
> +                                __func__, ret);
> +                       return false;
> +               }
> +
> +               if (!cur_buf) {
> +                       dev_info(hba->dev, "dCurWBBuf: %d WB disabled until free-
> space is available\n",
> +                                cur_buf);
> +                       return false;
> +               }
> +
> +               ret = ufshcd_get_ee_status(hba, &status);
> +               if (ret) {
> +                       dev_err(hba->dev, "%s: failed to get exception status %d\n",
> +                               __func__, ret);
> +                       if (avail_buf < UFS_WB_40_PERCENT_BUF_REMAIN) {
> +                               hba->dev_info.keep_vcc_on = true;
> +                               return true;
> +                       }
> +                       return false;
> +               }
> +
> +               status &= hba->ee_ctrl_mask;
> +
> +               if ((status & MASK_EE_URGENT_BKOPS) ||
So you are getting the status, but not the bkops level.
And what about WRITEBOOSTER_EVENT_EN? After all it was invented specifically for WB...

> +                   (avail_buf < UFS_WB_40_PERCENT_BUF_REMAIN)) {
> +                       hba->dev_info.keep_vcc_on = true;
> +                       return true;
> +               }
> +       }
> +       return false;
> +}

Thanks,
Avri

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