linux-kernel - Re: [PATCH v2 2/3] scsi: ufs: Keep device active mode only fWriteBoosterBufferFlushDuringHibernate == 1

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Date:   Mon, 7 Dec 2020 23:19:22 +0800
From:   Stanley Chu <stanley.chu@...iatek.com>
To:     Bean Huo <huobean@...il.com>
CC:     <alim.akhtar@...sung.com>, <avri.altman@....com>,
        <asutoshd@...eaurora.org>, <jejb@...ux.ibm.com>,
        <martin.petersen@...cle.com>, <beanhuo@...ron.com>,
        <bvanassche@....org>, <tomas.winkler@...el.com>,
        <cang@...eaurora.org>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] scsi: ufs: Keep device active mode only
 fWriteBoosterBufferFlushDuringHibernate == 1

On Mon, 2020-12-07 at 13:36 +0800, Stanley Chu wrote:
> On Sun, 2020-12-06 at 11:13 +0100, Bean Huo wrote:
> > From: Bean Huo <beanhuo@...ron.com>
> > 
> > According to the JEDEC UFS 3.1 Spec, If fWriteBoosterBufferFlushDuringHibernate
> > is set to one, the device flushes the WriteBooster Buffer data automatically
> > whenever the link enters the hibernate (HIBERN8) state. While the flushing
> > operation is in progress, the device should be kept in Active power mode.
> > Currently, we set this flag during the UFSHCD probe stage, but we didn't deal
> > with its programming failure. Even this failure is less likely to occur, but
> > still it is possible.
> > This patch is to add checkup of fWriteBoosterBufferFlushDuringHibernate setting,
> > keep the device as "active power mode" only when this flag be successfully set
> > to 1.
> > 
> > Fixes: 51dd905bd2f6 ("scsi: ufs: Fix WriteBooster flush during runtime suspend")
> > Signed-off-by: Bean Huo <beanhuo@...ron.com>
> > ---
> >  drivers/scsi/ufs/ufs.h    |  2 ++
> >  drivers/scsi/ufs/ufshcd.c | 20 +++++++++++++++-----
> >  2 files changed, 17 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
> > index d593edb48767..311d5f7a024d 100644
> > --- a/drivers/scsi/ufs/ufs.h
> > +++ b/drivers/scsi/ufs/ufs.h
> > @@ -530,6 +530,8 @@ struct ufs_dev_info {
> >  	bool f_power_on_wp_en;
> >  	/* Keeps information if any of the LU is power on write protected */
> >  	bool is_lu_power_on_wp;
> > +	/* Indicates if flush WB buffer during hibern8 successfully enabled */
> > +	bool is_hibern8_wb_flush;
> 
> Perhaps a more comprehensive name?
> For example, wb_flush_during_hibern8?
> >  	/* Maximum number of general LU supported by the UFS device */
> >  	u8 max_lu_supported;
> >  	u8 wb_dedicated_lu;
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index 30332592e624..da38d760944b 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -285,10 +285,16 @@ static inline void ufshcd_wb_config(struct ufs_hba *hba)
> >  		dev_err(hba->dev, "%s: Enable WB failed: %d\n", __func__, ret);
> >  	else
> >  		dev_info(hba->dev, "%s: Write Booster Configured\n", __func__);
> > +
> >  	ret = ufshcd_wb_toggle_flush_during_h8(hba, true);
> > -	if (ret)
> > +	if (ret) {
> >  		dev_err(hba->dev, "%s: En WB flush during H8: failed: %d\n",
> >  			__func__, ret);
> > +		hba->dev_info.is_hibern8_wb_flush = false;
> 
> Perhaps this statement could be dummy because
> hba->dev_info.is_hibern8_wb_flush is zero-initialized and
> ufshcd_wb_config() is invoked only once during ufs initialization.

Hi Bean,
Sorry to mislead you. ufshcd_wb_config() may be called multiple times by
both initialization and error recovery. Please ignore above suggestion.

Thanks,
Stanley Chu

> 
> Thanks,
> Stanley Chu
> 
> > +	} else {
> > +		hba->dev_info.is_hibern8_wb_flush = true;
> > +	}
> > +
> >  	ufshcd_wb_toggle_flush(hba, true);
> >  }
> >  
> > @@ -5448,6 +5454,7 @@ static bool ufshcd_wb_need_flush(struct ufs_hba *hba)
> >  
> >  	if (!ufshcd_is_wb_allowed(hba))
> >  		return false;
> > +
> >  	/*
> >  	 * The ufs device needs the vcc to be ON to flush.
> >  	 * With user-space reduction enabled, it's enough to enable flush
> > @@ -8540,6 +8547,7 @@ 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 hibern8;
> >  
> >  	hba->pm_op_in_progress = 1;
> >  	if (!ufshcd_is_shutdown_pm(pm_op)) {
> > @@ -8599,11 +8607,13 @@ 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.
> >  		 */
> > +		hibern8 = req_link_state == UIC_LINK_HIBERN8_STATE ||
> > +			(req_link_state == UIC_LINK_ACTIVE_STATE &&
> > +			 ufshcd_is_auto_hibern8_enabled(hba));
> > +
> >  		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))) &&
> > +			hba->auto_bkops_enabled || (hibern8 &&
> > +			hba->dev_info.is_hibern8_wb_flush &&
> >  			ufshcd_wb_need_flush(hba));
> >  	}
> >  
>