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    SubjectRe: [PATCH v1] scsi: ufs-mediatek: Enable UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL
    On 2020-12-24 21:47, Stanley Chu wrote:
    > Hi Avri, Bean,
    >
    > On Thu, 2020-12-24 at 13:01 +0100, Bean Huo wrote:
    >> On Thu, 2020-12-24 at 11:03 +0000, Avri Altman wrote:
    >> > > > Do you see any substantial benefit of having
    >> > > > fWriteBoosterBufferFlushEn
    >> > > > disabled?
    >> > >
    >> > > 1. The definition of fWriteBoosterBufferFlushEn is that host allows
    >> > > device to do flush in anytime after fWriteBoosterBufferFlushEn is
    >> > > set as
    >> > > on. This is not what we want.
    >> > >
    >> > > Just Like BKOP, We do not want flush happening beyond host's
    >> > > expected
    >> > > timing that device performance may be "randomly" dropped.
    >> >
    >> > Explicit flush takes place only when the device is idle:
    >> > if fWriteBoosterBufferFlushEn is set, the device is idle, and before
    >> > h8 received.
    >> > If a request arrives, the flush operation should be halted.
    >> > So no performance degradation is expected.
    >>
    >> Hi Stanley
    >>
    >> Avri's comment is correct, fWriteBoosterBufferFlushEn==1, device will
    >> flush only when it is in idle, once there is new incoming request, the
    >> flush will be suspended. You should be very careful when you want to
    >> skip this stetting of this flag.
    >
    > Very appreciate your the clarification.
    >
    > However similar to "Background Operations Termination Latency", while
    > the next request comes, device may need some time to suspend on-going
    > flush operations. This delay may "randomly" degrade the performance
    > right?

    That can be case by case (or vendor by vendor), but generally I agree
    with you on this.

    >
    > Since the configuration, i.e., enable
    > fWriteBoosterBufferFlushDuringHibernate only with
    > fWriteBoosterBufferFlushEn disabled, has been applied in many of our
    > mass-produced products these yeas, we would like to keep it unless the
    > new setting has obvious benefits.

    Thanks for sharing the info. I will leave the decision to Asutosh on
    this.

    Thanks,
    Can Guo.

    >
    > Thanks,
    > Stanley Chu
    >
    >>
    >> Bean
    >>

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