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Subject: Re: [PATCH v2 5/5] scsi: ufs: UFS Host Performance Booster(HPB)
 driver
To:     Avri Altman <Avri.Altman@wdc.com>,
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From:   Bart Van Assche <bvanassche@acm.org>
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Date:   Sat, 25 Apr 2020 10:51:52 -0700
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On 2020-04-25 01:59, Avri Altman wrote:
> One last word for the community members that are not into ufs day-to-day:
> 
> HPB implementation made its first public appearance around 2018 as part of Google's Pixel3 and some VIVO models.
> Since then, more and more mobile platforms are publically using HPB: Galaxy Note10,
> Galaxy S20 and VIVO NEX3 (that is already using HPB2.0), some Xiaomi models etc.
> 
> On the other hand, HPB1.0 spec was just recently closed - not even as part of UFS3.1,
> but only after - about 2 months ago. The industry is rushing forward, we've seen this many times.
> 
> The fact is that HPB is here to stay - either as a horde of out-of-tree implementations,
> or as a standard acceptable mainline driver.

Hi Avri,

Thanks for the additional clarification. I think we need HPB support in
the upstream kernel. A possible approach is to start a discussion about
how to integrate HPB support in the upstream kernel and to defer posting
new implementations until agreement about an approach has been achieved.
Is there e.g. an alternative for avoiding deadlocks other than using the
blk-mq reserved tag feature for the commands that manage the L2P tables?

Thanks,

Bart.