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Subject: Re: [PATCH v3 2/3] scsi: ufs: Keep device active mode only
 fWriteBoosterBufferFlushDuringHibernate == 1
From:   Bean Huo <huobean@gmail.com>
To:     Avri Altman <Avri.Altman@wdc.com>,
        "alim.akhtar@samsung.com" <alim.akhtar@samsung.com>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
        "jejb@linux.ibm.com" <jejb@linux.ibm.com>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "stanley.chu@mediatek.com" <stanley.chu@mediatek.com>,
        "beanhuo@micron.com" <beanhuo@micron.com>,
        "bvanassche@acm.org" <bvanassche@acm.org>,
        "tomas.winkler@intel.com" <tomas.winkler@intel.com>,
        "cang@codeaurora.org" <cang@codeaurora.org>
Cc:     "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Date:   Wed, 09 Dec 2020 23:03:59 +0100
In-Reply-To: <DM6PR04MB6575B928898B319E8ACF1395FCCC0@DM6PR04MB6575.namprd04.prod.outlook.com>
References: <20201208210941.2177-1-huobean@gmail.com>
         <20201208210941.2177-3-huobean@gmail.com>
         <DM6PR04MB6575B928898B319E8ACF1395FCCC0@DM6PR04MB6575.namprd04.prod.outlook.com>
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On Wed, 2020-12-09 at 07:40 +0000, Avri Altman wrote:
> > 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.
> 
> How about reading it on every ufshcd_wb_need_flush?
> 
> Thanks,
> Avri


Hi Avri
I was using that way, no different from the current my way. Instead,
reading on every time will add some delay. As long as the UFS device
returns the successful, we assume that this flag has been properly
set.  so, just keeping is_hibern8_wb_flush if set, I think it is
enough.

Thanks,
Bean