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From:   Avri Altman <Avri.Altman@wdc.com>
To:     "Bean Huo (beanhuo)" <beanhuo@micron.com>,
        "hch@infradead.org" <hch@infradead.org>
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Subject: RE: [EXT] Re: [PATCH v2 0/5] UFS Host Performance Booster (HPB v1.0)
 driver
Thread-Topic: [EXT] Re: [PATCH v2 0/5] UFS Host Performance Booster (HPB v1.0)
 driver
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Date:   Thu, 23 Apr 2020 08:26:27 +0000
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=20
>=20
> Hi, Christoph
> Thanks for your feedback.
>=20
> > > To avoid touching the traditional SCSI core, the HPB driver in this
> > > series HPB patch chooses to develop under SCSI sub-system layer, and
> > > sits the same layer with UFSHCD. At the same time, to minimize change=
s
> > > to UFSHCD driver, the HPB driver submits its HPB READ BUFFER and HPB
> > > WRITE BUFFER requests to the scsi
> > > device->request_queueu to execute, rather than that directly go
> > > device->through
> > > raw UPIU request path.
> >
> > This feature is completley broken, and rather dangerous due to feeding
> > "physical" addresses looked up by the host in.  I do not think we shoul=
d
> support
> > something that broken in Linux.
> >
>=20
> It Is not plain physical address,  has been encrypted before loading from=
 UFS
> to
> HPB memory, I think we don't worry about its safety.
>=20
> > Independent of that using two requests in the I/O path is not going to =
fly
> either.
> > The whole thing seems like an exercise in benchmarketing.
>=20
> I agree with you. This is my major concern. I have been thinking about HP=
B
> implementation in SCSI layer.
> That will let SCSI layer manage HPB by calling UFS helper interface.
> If you don't consider UFS HPB is an idiot design,  I want to  change in a=
nother
> version.  Firstly, we really
> want to hear your suggestion.
> Thanks,
>=20
> //Bean

If indeed this will move forward, please publish your patches as a RFC,
To allow competing approaches to be published as well.

Thanks,
Avri