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Message-ID: <eee9f5b0a1f9e52a1ea569403cc183fb48dd77a9.camel@gmail.com>
Subject: Re: [PATCH v5 1/7] scsi: ufs: Add "wb_on" sysfs node to control WB
 on/off
From:   Bean Huo <huobean@gmail.com>
To:     Stanley Chu <stanley.chu@mediatek.com>
Cc:     alim.akhtar@samsung.com, avri.altman@wdc.com,
        asutoshd@codeaurora.org, jejb@linux.ibm.com,
        martin.petersen@oracle.com, beanhuo@micron.com, bvanassche@acm.org,
        tomas.winkler@intel.com, cang@codeaurora.org,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Tue, 22 Dec 2020 22:08:56 +0100
In-Reply-To: <4c15956660bd7305b0c095603bfa0e30c7f1610e.camel@gmail.com>
References: <20201215230519.15158-1-huobean@gmail.com>
         <20201215230519.15158-2-huobean@gmail.com>
         <1608617307.14045.3.camel@mtkswgap22>
         <4c15956660bd7305b0c095603bfa0e30c7f1610e.camel@gmail.com>
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On Tue, 2020-12-22 at 21:50 +0100, Bean Huo wrote:
> > 
> > May this operation race with UFS shutdown flow?
> > 
> > To be more clear, ufshcd_wb_ctrl() here may be executed after host
> > clock
> > is disabled by shutdown flow?
> > 
> > If yes, we need to avoid it.
> > 
> > Thanks,
> > Stanley Chu
> 
> Yes, it is quite possible, but who will mess up this on purpose?
> 
> ok, to counterbalance our concerns, I can add checkup:
> 
> 
> /* UFS device & link must be active before we change WB status */
> if (!ufshcd_is_ufs_dev_active(hba) || !ufshcd_is_link_active(hba))
>         return -EINVAL;
> 
> 
> how do you think about?
> 
> Bean

seems there are only auto_hibern8 and wb will issue command to UFS
device. if you think auto_hibern8 also needs this protection.

I will add in the next version patch, otherwise, just add this checkup
in the WB.

Look forward to your feedback!

Thanks,
Bean