From: Avri Altman <Avri.Altman@wdc.com>
To: Stanley Chu <stanley.chu@mediatek.com>,
Bart Van Assche <bvanassche@acm.org>
Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"alim.akhtar@samsung.com" <alim.akhtar@samsung.com>,
"jejb@linux.ibm.com" <jejb@linux.ibm.com>,
"beanhuo@micron.com" <beanhuo@micron.com>,
"asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
"cang@codeaurora.org" <cang@codeaurora.org>,
"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
"linux-mediatek@lists.infradead.org"
<linux-mediatek@lists.infradead.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kuohong.wang@mediatek.com" <kuohong.wang@mediatek.com>,
"peter.wang@mediatek.com" <peter.wang@mediatek.com>,
"chun-hung.wu@mediatek.com" <chun-hung.wu@mediatek.com>,
"andy.teng@mediatek.com" <andy.teng@mediatek.com>,
"chaotian.jing@mediatek.com" <chaotian.jing@mediatek.com>,
"cc.chou@mediatek.com" <cc.chou@mediatek.com>
Subject: RE: [PATCH v3] scsi: ufs: Cleanup completed request without interrupt notification
Date: Mon, 13 Jul 2020 08:10:29 +0000 [thread overview]
Message-ID: <SN6PR04MB46409838AE9D4BD63797E26DFC600@SN6PR04MB4640.namprd04.prod.outlook.com> (raw)
In-Reply-To: <1594607245.22878.8.camel@mtkswgap22>
>
> Hi Bart and Avri,
>
> On Sun, 2020-07-12 at 18:39 -0700, Bart Van Assche wrote:
> > On 2020-07-06 06:21, Stanley Chu wrote:
> > > If somehow no interrupt notification is raised for a completed request
> > > and its doorbell bit is cleared by host, UFS driver needs to cleanup
> > > its outstanding bit in ufshcd_abort().
> >
> > How is it possible that no interrupt notification is raised for a completed
> > request? Is this the result of a hardware shortcoming or rather the result
> > of how the UFS driver works? In the latter case, is this patch perhaps a
> > workaround? If so, has it been considered to fix the root cause instead of
> > implementing a workaround?
>
> Actually this fail is triggered by "error injection" to produce a
> command timeout event for checking if anything can be improved or fixed.
>
> I agree that "no interrupt notification" may be something wrong in
> hardware and the root cause shall be fixed in the highest priority.
> However from this injection, we found ufshcd_abort() indeed has a defect
> flow for a corner case, so we are looking for the solution to fix the
> "hole".
>
> What would you think if Linux driver shall consider this case? If this
> is not necessary, I would drop this patch : )
Artificially injecting errors is a very common validation mechanism,
Provided that you are not breaking anything of the upper-layers,
Which I don't think you are doing.
Can you refer please to my last comment?
>
> Thanks a lot,
> Stanley Chu
>
> >
> > In section 7.2.3 of the UFS specification I found the following about how
> > to process request completions: "Software determines if new TRs have
> > completed since step #2, by repeating one of the two methods described in
> > step #2. If new TRs have completed, software repeats the sequence from
> step
> > #3." Is such a loop perhaps missing from the Linux UFS driver?
Could not find that citation.
What version of the spec are you using?
Thanks,
Avri
> >
> > Thanks,
> >
> > Bart.
next prev parent reply other threads:[~2020-07-13 8:10 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 13:21 [PATCH v3] scsi: ufs: Cleanup completed request without interrupt notification Stanley Chu
2020-07-09 8:31 ` Avri Altman
2020-07-12 1:26 ` Stanley Chu
2020-07-12 10:04 ` Avri Altman
2020-07-14 8:48 ` Stanley Chu
2020-07-14 9:29 ` Avri Altman
2020-07-14 10:00 ` Stanley Chu
2020-07-13 1:39 ` Bart Van Assche
2020-07-13 2:27 ` Stanley Chu
2020-07-13 8:10 ` Avri Altman [this message]
2020-07-15 4:00 ` Bart Van Assche
2020-07-22 10:07 ` Stanley Chu
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