Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH] scsi: ufshpb: Opt out pre-reqs from HPB2.0 flows
To:     Avri Altman <avri.altman@wdc.com>,
        "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>
Cc:     linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        Adrian Hunter <adrian.hunter@intel.com>,
        Bean Huo <beanhuo@micron.com>,
        Daejun Park <daejun7.park@samsung.com>,
        James Bottomley <James.Bottomley@HansenPartnership.com>
References: <20211029155754.3287-1-avri.altman@wdc.com>
From:   Bart Van Assche <bvanassche@acm.org>
Message-ID: <52dbffa7-6549-1f1d-cc2d-9022e65b59a9@acm.org>
Date:   Fri, 29 Oct 2021 09:10:10 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.14.0
MIME-Version: 1.0
In-Reply-To: <20211029155754.3287-1-avri.altman@wdc.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 10/29/21 8:57 AM, Avri Altman wrote:
> HPB allows its read commands to carry the physical addresses along with
> the LBAs, thus allowing less internal L2P-table switches in the device.
> HPB1.0 allowed a single LBA, while HPB2.0 increases this capacity up to
> 255 blocks.
> 
> Carrying more than a single record, the read operation is no longer
> purly of type "read" per-se, but some sort of a "hybrid" command -
   ^^^^^
   purely?
> writing the physical address to the device and reading the required
> payload.
> 
> The HPB JEDEC spec came-up with a dual-command for that operation:
> HPB-WRITE-BUFFER (0x2) to write the physical addresses to device, and
> HPB-READ to read the payload.
> 
> Alas, the current HPB driver design - a single-scsi-LLD-module, has no
> other alternative but to spawn the READ10 command into 2 commands:
> HPB-WRITE-BUFFER and HPB-READ.
> This causes a grat deal of aggrevation to the block layer guys, up to a
> point, in which that they were willing to revert the entire HPB driver,
> regardless of the huge amount of corporate effort already inversted in
> it.
> 
> Therefore, remove the pre-req API for now, as a matter of urgency to get
> it done before the closing of the merge window.

Anyway:

Reviewed-by: Bart Van Assche <bvanassche@acm.org>