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Date: Wed, 20 May 2020 15:23:28 +0800
From: Stanley Chu <stanley.chu@...iatek.com>
To: "Asutosh Das (asd)" <asutoshd@...eaurora.org>
CC: <linux-scsi@...r.kernel.org>, <martin.petersen@...cle.com>,
<avri.altman@....com>, <alim.akhtar@...sung.com>,
<jejb@...ux.ibm.com>, <beanhuo@...ron.com>, <cang@...eaurora.org>,
<matthias.bgg@...il.com>, <bvanassche@....org>,
<linux-mediatek@...ts.infradead.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <kuohong.wang@...iatek.com>,
<peter.wang@...iatek.com>, <chun-hung.wu@...iatek.com>,
<andy.teng@...iatek.com>
Subject: Re: [PATCH v3 5/5] scsi: ufs: Fix possible VCC power drain during
runtime suspend
Hi, Asutosh,
Thanks for your review.
On Tue, 2020-05-19 at 09:27 -0700, Asutosh Das (asd) wrote:
> Hi Stanley,
>
> On 5/16/2020 10:46 AM, Stanley Chu wrote:
> > The commit "scsi: ufs: Fix WriteBooster flush during runtime
> > suspend" promises essential resource, i.e., for UFS devices doing
> > WriteBooster buffer flush and Auto BKOPs. However if device
> > finishes its job but not resumed for a very long time, system
> > will have unnecessary power drain because VCC is still supplied.
> >
> > To fix this, a method to recheck the threshold of keeping VCC
> > supply is required. However, the threshold recheck needs to
> > re-activate the link because the decision depends on the device
> > status.
> >
> > Introduce a delayed work to force runtime resume after a certain
> > delay during runtime suspend. This makes threshold recheck simpler
> > which will be done in the next runtime-suspend.
> >
> > Signed-off-by: Stanley Chu <stanley.chu@...iatek.com>
> > ---
>
> Is there a reason to have this code as a separate patch?
> [1] Commit: "scsi: ufs: Fix WriteBooster flush during runtime suspend"
> introduces 'keep_curr_dev_pwr_mode' and the very next change (this one)
> removes it.
> Do you think this change and [1] should be merged?
Yes, these 2 patches shall be merged. I will do it in next version.
>
> > drivers/scsi/ufs/ufs.h | 1 +
> > drivers/scsi/ufs/ufshcd.c | 43 ++++++++++++++++++++++++++++++++++-----
> > drivers/scsi/ufs/ufshcd.h | 1 +
> > 3 files changed, 40 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
> > index db07eedfed96..c70845d41449 100644
> > --- a/drivers/scsi/ufs/ufs.h
> > +++ b/drivers/scsi/ufs/ufs.h
> > @@ -574,6 +574,7 @@ struct ufs_dev_info {
> > u32 d_ext_ufs_feature_sup;
> > u8 b_wb_buffer_type;
> > u32 d_wb_alloc_units;
> > + bool b_rpm_dev_flush_capable;
> > u8 b_presrv_uspc_en;
> > };
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index f4f2c7b5ab0a..a137553f9b41 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -94,6 +94,9 @@
> > /* default delay of autosuspend: 2000 ms */
> > #define RPM_AUTOSUSPEND_DELAY_MS 2000
> >
> > +/* Default delay of RPM device flush delayed work */
> > +#define RPM_DEV_FLUSH_RECHECK_WORK_DELAY_MS 5000
> > +
> > /* Default value of wait time before gating device ref clock */
> > #define UFSHCD_REF_CLK_GATING_WAIT_US 0xFF /* microsecs */
> >
> > @@ -5310,7 +5313,7 @@ static bool ufshcd_wb_presrv_usrspc_keep_vcc_on(struct ufs_hba *hba,
> > return false;
> > }
> >
> > -static bool ufshcd_wb_keep_vcc_on(struct ufs_hba *hba)
> > +static bool ufshcd_wb_need_flush(struct ufs_hba *hba)
> > {
> > int ret;
> > u32 avail_buf;
> > @@ -5348,6 +5351,21 @@ static bool ufshcd_wb_keep_vcc_on(struct ufs_hba *hba)
> > return ufshcd_wb_presrv_usrspc_keep_vcc_on(hba, avail_buf);
> > }
> >
> > +static void ufshcd_rpm_dev_flush_recheck_work(struct work_struct *work)
> > +{
> > + struct ufs_hba *hba = container_of(to_delayed_work(work),
> > + struct ufs_hba,
> > + rpm_dev_flush_recheck_work);
> > + /*
> > + * To prevent unnecessary VCC power drain after device finishes
> > + * WriteBooster buffer flush or Auto BKOPs, force runtime resume
> > + * after a certain delay to recheck the threshold by next runtime
> > + * supsend.
> > + */
> > + pm_runtime_get_sync(hba->dev);
> > + pm_runtime_put_sync(hba->dev);
> > +}
> > +
> > /**
> > * ufshcd_exception_event_handler - handle exceptions raised by device
> > * @work: pointer to work data
> > @@ -8164,7 +8182,6 @@ 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)) {
> > @@ -8224,11 +8241,12 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
> > * Hibern8, keep device power mode as "active power mode"
> > * and VCC supply.
> > */
> > - keep_curr_dev_pwr_mode = hba->auto_bkops_enabled ||
> > + hba->dev_info.b_rpm_dev_flush_capable =
> > + hba->auto_bkops_enabled ||
> > (((req_link_state == UIC_LINK_HIBERN8_STATE) ||
> > ((req_link_state == UIC_LINK_ACTIVE_STATE) &&
> > ufshcd_is_auto_hibern8_enabled(hba))) &&
> > - ufshcd_wb_keep_vcc_on(hba));
> > + ufshcd_wb_need_flush(hba));
> > }
> >
> > if (req_dev_pwr_mode != hba->curr_dev_pwr_mode) {
> > @@ -8238,7 +8256,7 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
> > ufshcd_disable_auto_bkops(hba);
> > }
> >
> > - if (!keep_curr_dev_pwr_mode) {
> > + if (!hba->dev_info.b_rpm_dev_flush_capable) {
> > ret = ufshcd_set_dev_pwr_mode(hba, req_dev_pwr_mode);
> > if (ret)
> > goto enable_gating;
> > @@ -8295,9 +8313,16 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
> > if (hba->clk_scaling.is_allowed)
> > ufshcd_resume_clkscaling(hba);
> > hba->clk_gating.is_suspended = false;
> > + hba->dev_info.b_rpm_dev_flush_capable = false;
> > ufshcd_release(hba);
> > out:
> > + if (hba->dev_info.b_rpm_dev_flush_capable) {
> > + schedule_delayed_work(&hba->rpm_dev_flush_recheck_work,
> > + msecs_to_jiffies(RPM_DEV_FLUSH_RECHECK_WORK_DELAY_MS));
> > + }
> > +
> > hba->pm_op_in_progress = 0;
> > +
> Nitpick; newline, perhaps?
Thanks, I Will remove it.
>
> > if (ret)
> > ufshcd_update_reg_hist(&hba->ufs_stats.suspend_err, (u32)ret);
> > return ret;
> > @@ -8386,6 +8411,11 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
> > /* Enable Auto-Hibernate if configured */
> > ufshcd_auto_hibern8_enable(hba);
> >
> > + if (hba->dev_info.b_rpm_dev_flush_capable) {
> > + hba->dev_info.b_rpm_dev_flush_capable = false;
> > + cancel_delayed_work(&hba->rpm_dev_flush_recheck_work);
> > + }
> > +
> > /* Schedule clock gating in case of no access to UFS device yet */
> > ufshcd_release(hba);
> >
> > @@ -8859,6 +8889,9 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
> > UFS_SLEEP_PWR_MODE,
> > UIC_LINK_HIBERN8_STATE);
> >
> > + INIT_DELAYED_WORK(&hba->rpm_dev_flush_recheck_work,
> > + ufshcd_rpm_dev_flush_recheck_work);
> > +
> > /* Set the default auto-hiberate idle timer value to 150 ms */
> > if (ufshcd_is_auto_hibern8_supported(hba) && !hba->ahit) {
> > hba->ahit = FIELD_PREP(UFSHCI_AHIBERN8_TIMER_MASK, 150) |
> > diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> > index 8db7a6101892..9acd437037e8 100644
> > --- a/drivers/scsi/ufs/ufshcd.h
> > +++ b/drivers/scsi/ufs/ufshcd.h
> > @@ -745,6 +745,7 @@ struct ufs_hba {
> > struct request_queue *bsg_queue;
> > bool wb_buf_flush_enabled;
> > bool wb_enabled;
> > + struct delayed_work rpm_dev_flush_recheck_work;
> > };
> >
> > /* Returns true if clocks can be gated. Otherwise false */
> >
>
>
Thanks,
Stanley Chu
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