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From:   Rob Clark <robdclark@gmail.com>
Date:   Sun, 21 Jun 2020 09:50:43 -0700
Message-ID: <CAF6AEGuG3XAqN_sedxk9GRm_9yK+a4OH56CZPmbHx+SW-FNVPQ@mail.gmail.com>
Subject: Re: [PATCH v1 1/3] scsi: ufs: add write booster feature support
To:     Bjorn Andersson <bjorn.andersson@linaro.org>
Cc:     Avri Altman <Avri.Altman@wdc.com>,
        Asutosh Das <asutoshd@codeaurora.org>,
        "cang@codeaurora.org" <cang@codeaurora.org>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        Subhash Jadavani <subhashj@codeaurora.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        Bean Huo <beanhuo@micron.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Tomas Winkler <tomas.winkler@intel.com>,
        Colin Ian King <colin.king@canonical.com>,
        Bart Van Assche <bvanassche@acm.org>,
        open list <linux-kernel@vger.kernel.org>
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On Sun, Jun 21, 2020 at 12:58 AM Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> On Sun 21 Jun 00:40 PDT 2020, Avri Altman wrote:
>
> >
> > >
> > > On Wed, Apr 8, 2020 at 3:00 PM Asutosh Das <asutoshd@codeaurora.org>
> > > wrote:
> > > >
> > > > The write performance of TLC NAND is considerably
> > > > lower than SLC NAND. Using SLC NAND as a WriteBooster
> > > > Buffer enables the write request to be processed with
> > > > lower latency and improves the overall write performance.
> > > >
> > > > Adds support for shared-buffer mode WriteBooster.
> > > >
> > > > WriteBooster enable: SW enables it when clocks are
> > > > scaled up, thus it's enabled only in high load conditions.
> > > >
> > > > WriteBooster disable: SW will disable the feature,
> > > > when clocks are scaled down. Thus writes would go as normal
> > > > writes.
> > >
> > > btw, in v5.8-rc1 (plus handful of remaining patches for lenovo c630
> > > laptop (sdm850)), I'm seeing a lot of:
> > >
> > >   ufshcd-qcom 1d84000.ufshc: ufshcd_query_flag: Sending flag query for
> > > idn 14 failed, err = 253
> > >   ufshcd-qcom 1d84000.ufshc: ufshcd_query_flag: Sending flag query for
> > > idn 14 failed, err = 253
> > >   ufshcd-qcom 1d84000.ufshc: ufshcd_query_flag_retry: query attribute,
> > > opcode 6, idn 14, failed with error 253 after 3 retires
> > >   ufshcd-qcom 1d84000.ufshc: ufshcd_wb_ctrl write booster enable failed 253
> > >
> > > and at least subjectively, compiling mesa seems slower, which seems
> > > like it might be related?
> > This looks like a device issue to be taken with the flash vendor:
>
> There's no way for a end-user to file a bug report with the flash vendor
> on a device bought from an OEM and even if they would accept the bug
> report they wouldn't re-provision the flash in an shipped device.
>
> So you will have to work around this in the driver.

oh, ugg.. well I think these msgs from dmesg identify the part if we
end up needing to use a denylist:

scsi 0:0:0:49488: Well-known LUN    SKhynix  H28S8Q302CMR     A102 PQ: 0 ANSI: 6
scsi 0:0:0:49476: Well-known LUN    SKhynix  H28S8Q302CMR     A102 PQ: 0 ANSI: 6
scsi 0:0:0:49456: Well-known LUN    SKhynix  H28S8Q302CMR     A102 PQ: 0 ANSI: 6
scsi 0:0:0:0: Direct-Access     SKhynix  H28S8Q302CMR     A102 PQ: 0 ANSI: 6
scsi 0:0:0:1: Direct-Access     SKhynix  H28S8Q302CMR     A102 PQ: 0 ANSI: 6
sd 0:0:0:0: [sda] 29765632 4096-byte logical blocks: (122 GB/114 GiB)
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Mode Sense: 00 32 00 10
sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, supports
DPO and FUA
sd 0:0:0:0: [sda] Optimal transfer size 786432 bytes
scsi 0:0:0:2: Direct-Access     SKhynix  H28S8Q302CMR     A102 PQ: 0 ANSI: 6
scsi 0:0:0:3: Direct-Access     SKhynix  H28S8Q302CMR     A102 PQ: 0 ANSI: 6


(otoh I guess the driver could just notice that writeboost keeps
failing and stop trying to use it)

BR,
-R


> Regards,
> Bjorn
>
> > The device reports that it supports wd, but returns inalid idn for flag 0xe...
> >
> > Thanks,
> > Avri