From: Stanley Chu <stanley.chu@mediatek.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: <linux-scsi@vger.kernel.org>, <martin.petersen@oracle.com>,
<avri.altman@wdc.com>, <alim.akhtar@samsung.com>,
<jejb@linux.ibm.com>, <beanhuo@micron.com>,
<asutoshd@codeaurora.org>, <cang@codeaurora.org>,
<matthias.bgg@gmail.com>, <linux-mediatek@lists.infradead.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <kuohong.wang@mediatek.com>,
<peter.wang@mediatek.com>, <chun-hung.wu@mediatek.com>,
<andy.teng@mediatek.com>, <chaotian.jing@mediatek.com>,
<cc.chou@mediatek.com>
Subject: Re: [PATCH v3] scsi: ufs: Cleanup completed request without interrupt notification
Date: Mon, 13 Jul 2020 10:27:25 +0800 [thread overview]
Message-ID: <1594607245.22878.8.camel@mtkswgap22> (raw)
In-Reply-To: <3d509c4b-d66d-2a4a-5fbd-a50a0610ad31@acm.org>
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 : )
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?
>
> Thanks,
>
> Bart.
next prev parent reply other threads:[~2020-07-13 2:27 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 [this message]
2020-07-13 8:10 ` Avri Altman
2020-07-15 4:00 ` Bart Van Assche
2020-07-22 10:07 ` Stanley Chu
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