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Subject: Re: [PATCH v3] scsi: ufs: Cleanup completed request without interrupt
 notification
To:     Stanley Chu <stanley.chu@mediatek.com>, linux-scsi@vger.kernel.org,
        martin.petersen@oracle.com, avri.altman@wdc.com,
        alim.akhtar@samsung.com, jejb@linux.ibm.com
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References: <20200706132113.21096-1-stanley.chu@mediatek.com>
From:   Bart Van Assche <bvanassche@acm.org>
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Date:   Sun, 12 Jul 2020 18:39:26 -0700
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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?

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.