Messages in this thread | | | Subject | Re: [PATCH v1 4/4] scsi: ufs: Fix WriteBooster flush during runtime suspend | From | "Asutosh Das (asd)" <> | Date | Thu, 14 May 2020 09:59:19 -0700 |
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On 5/14/2020 7:49 AM, Stanley Chu wrote: > 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@mediatek.com> >>>> --- >>>> 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@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-mediatek >
Hi Stanley, I think that'd work, but there's definitely a penalty of keeping Vcc ON. And if we do want to keep it ON, then we'd have to measure how much excess power is being used - after the flush is done.
I think setting keep_curr_dev_pwr_mode to true iff h8 and ah8 are enabled is a good idea. In addition to that, adding a timer to check flush status if keep_curr_dev_pwr_mode is set to true would keep the power consumption to a minimum. So I suggest to have the delayed check of flush status as well.
Thanks, -asd
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