Re: [<RFC PATCH v1> 1/2] scsi: ufs: add write booster feature support

[Asutosh Das (asd)]

On 2/25/2020 4:50 AM, Avri Altman wrote:
> > +/*
> > + * 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

Thanks Avri/Bart for the comments.
I'll wait for a couple of more days, if anyone else has any comments.

I'd respond/address the comments thereafter.

Thanks,
asd

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