Hi Asutosh, On Thu, 2020-05-14 at 10:23 +0800, Stanley Chu wrote: > Hi Asutosh, > > On Wed, 2020-05-13 at 12:31 -0700, Asutosh Das (asd) wrote: > > On 5/12/2020 3:47 AM, Stanley Chu wrote: > > > Currently UFS host driver promises VCC supply if UFS device > > > needs to do WriteBooster flush during runtime suspend. > > > > > > However the UFS specification mentions, > > > > > > "While the flushing operation is in progress, the device is > > > in Active power mode." > > > > > > Therefore UFS host driver needs to promise more: Keep UFS > > > device as "Active power mode", otherwise UFS device shall not > > > do any flush if device enters Sleep or PowerDown power mode. > > > > > > Fix this by not changing device power mode if WriteBooster > > > flush is required in ufshcd_suspend(). > > > > > > Signed-off-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx> > > > --- > > > drivers/scsi/ufs/ufs.h | 1 - > > > drivers/scsi/ufs/ufshcd.c | 39 +++++++++++++++++++-------------------- > > > 2 files changed, 19 insertions(+), 21 deletions(-) > > > > > > diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h > > > index b3135344ab3f..9e4bc2e97ada 100644 > > > --- a/drivers/scsi/ufs/ufs.h > > > +++ b/drivers/scsi/ufs/ufs.h > > > @@ -577,7 +577,6 @@ struct ufs_dev_info { > > > u32 d_ext_ufs_feature_sup; > > > u8 b_wb_buffer_type; > > > u32 d_wb_alloc_units; > > > - bool keep_vcc_on; > > > u8 b_presrv_uspc_en; > > > }; > > > > > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > > > index 169a3379e468..2d0aff8ac260 100644 > > > --- a/drivers/scsi/ufs/ufshcd.c > > > +++ b/drivers/scsi/ufs/ufshcd.c > > > @@ -8101,8 +8101,7 @@ static void ufshcd_vreg_set_lpm(struct ufs_hba *hba) > > > !hba->dev_info.is_lu_power_on_wp) { > > > ufshcd_setup_vreg(hba, false); > > > } else if (!ufshcd_is_ufs_dev_active(hba)) { > > > - if (!hba->dev_info.keep_vcc_on) > > > - ufshcd_toggle_vreg(hba->dev, hba->vreg_info.vcc, false); > > > + ufshcd_toggle_vreg(hba->dev, hba->vreg_info.vcc, false); > > > if (!ufshcd_is_link_active(hba)) { > > > ufshcd_config_vreg_lpm(hba, hba->vreg_info.vccq); > > > ufshcd_config_vreg_lpm(hba, hba->vreg_info.vccq2); > > > @@ -8172,6 +8171,7 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op) > > > enum ufs_pm_level pm_lvl; > > > enum ufs_dev_pwr_mode req_dev_pwr_mode; > > > enum uic_link_state req_link_state; > > > + bool keep_curr_dev_pwr_mode = false; > > > > > > hba->pm_op_in_progress = 1; > > > if (!ufshcd_is_shutdown_pm(pm_op)) { > > > @@ -8226,28 +8226,27 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op) > > > /* make sure that auto bkops is disabled */ > > > ufshcd_disable_auto_bkops(hba); > > > } > > > + > > Unnecessary newline, perhaps? > > Yap, I will remove it in next version. > > > > /* > > > - * With wb enabled, if the bkops is enabled or if the > > > - * configured WB type is 70% full, keep vcc ON > > > - * for the device to flush the wb buffer > > > + * If device needs to do BKOP or WB buffer flush, keep device > > > + * power mode as "active power mode" and its VCC supply. > > > */ > > > - if ((hba->auto_bkops_enabled && ufshcd_is_wb_allowed(hba)) || > > > - ufshcd_wb_keep_vcc_on(hba)) > > > - hba->dev_info.keep_vcc_on = true; > > > - else > > > - hba->dev_info.keep_vcc_on = false; > > > - } else { > > > - hba->dev_info.keep_vcc_on = false; > > > + keep_curr_dev_pwr_mode = hba->auto_bkops_enabled || > > > + ufshcd_wb_keep_vcc_on(hba); > > Should the device be in UFS_ACTIVE_PWR_MODE to perform auto-bkops? > > > > Also, is it needed to keep the device in UFS_ACTIVE_PWR_MODE , if flush > > on hibern8 is enabled and the link is being put to hibern8 mode during > > runtime-suspend? Perhaps that should also be factored in here? > > Both auto-bkops and WriteBooster flush during Hibern8 need device power > mode to be "Active Power Mode". > > For auto-bkops, the spec mentions, > > "If the background operations enable bit is set and the device is in > Active power mode or Idle power mode, then the device is allowed to > execute any internal operations." > > For WriteBooster flush during Hibern8, the spec mentions, > > "While the flushing operation is in progress, the device is in Active > power mode." > > Therefore here we can use an unified "keep_curr_dev_pwr_mode" to > indicate the same requirements of above both features. > > Besides, both operations may access flash array inside UFS device thus > VCC supply shall be also kept. > > Before this patch, the original code will keep device power mode (stay > in Active Power Mode) if hba->auto_bkops_enabled is set as true during > runtime-suspend with UFSHCD_CAP_AUTO_BKOPS_SUSPEND capability is > enabled. This patch will not change this decision, just add > "WriteBooster flush during Hibern8" feature as another condition to do > so. > > Thank you so much to remind me that "Link shall be put in Hibern8" is a > necessary condition for "WriteBooster flush during Hibern8". I will add > more checking for keep_curr_dev_pwr_mode to prevent unnecessary power > drain. > > > > } > > > > > > - if ((req_dev_pwr_mode != hba->curr_dev_pwr_mode) && > > > - ((ufshcd_is_runtime_pm(pm_op) && !hba->auto_bkops_enabled) || > > > - !ufshcd_is_runtime_pm(pm_op))) { > > > - /* ensure that bkops is disabled */ > > > - ufshcd_disable_auto_bkops(hba); > > > - ret = ufshcd_set_dev_pwr_mode(hba, req_dev_pwr_mode); > > > - if (ret) > > > - goto enable_gating; > > > + if (req_dev_pwr_mode != hba->curr_dev_pwr_mode) { > > > + if ((ufshcd_is_runtime_pm(pm_op) && !hba->auto_bkops_enabled) || > > > + !ufshcd_is_runtime_pm(pm_op)) { > > > + /* ensure that bkops is disabled */ > > > + ufshcd_disable_auto_bkops(hba); > > > + } > > > + > > > + if (!keep_curr_dev_pwr_mode) { > > > + ret = ufshcd_set_dev_pwr_mode(hba, req_dev_pwr_mode); > > > > Now, when the WB buffer is completely flushed out, the device should be > > put back into UFS_SLEEP_PWR_MODE or UFS_POWERDOWN_PWR_MODE. Say, the > > device buffer has to be flushed and during runtime-suspend, the device > > is put to UFS_ACTIVE_PWR_MODE and Vcc is kept ON; the device doesn't > > resume nor does the system enters suspend for a very long time, and with > > AH8 and hibern8 disabled, there will be an unnecessary power drain for > > that much time. Another thought is that if keep_curr_dev_pwr_mode will be set as true only if link is put in Hibern8 or Auto-Hibern8 is enabled. By this way, the power consumption shall be very small after flush or auto-bkop is finished. Then the checking of flush status during runtime-suspend may be not necessary. > > > > How about a periodic interval checking of flush status if > > keep_curr_dev_pwr_mode evaluates to be true? > > This is a good point! > > The same thing also happens for auto-bkops. How about add a timer to > leave runtime suspend if keep_curr_dev_pwr_mode is set as true? This is > simple and also favors power. The timeout value could be adjustable > according to the available WriteBooster buffer size. > > A periodic interval checking of flush status needs to re-activate link > to communicate with the device. This would be tricky and the > re-activation flow is just like runtime-resume. > > What would you think? > > Thanks. > Stanley Chu > > > _______________________________________________ > Linux-mediatek mailing list > Linux-mediatek@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-mediatek