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Date:   Tue, 29 Oct 2019 10:37:45 +0800
From:   cang@codeaurora.org
To:     Avri Altman <Avri.Altman@wdc.com>
Cc:     "Winkler, Tomas" <tomas.winkler@intel.com>,
        asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        rnayak@codeaurora.org, linux-scsi@vger.kernel.org,
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        Alim Akhtar <alim.akhtar@samsung.com>,
        Pedro Sousa <pedrom.sousa@synopsys.com>,
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        Bean Huo <beanhuo@micron.com>,
        Subhash Jadavani <subhashj@codeaurora.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 1/1] scsi: ufs: Add command logging infrastructure
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On 2019-10-23 18:33, Avri Altman wrote:
>> 
>> > Add the necessary infrastructure to keep timestamp history of
>> > commands, events and other useful info for debugging complex issues.
>> > This helps in diagnosing events leading upto failure.
>> 
>> Why not use tracepoints, for that?
> Ack on Tomas's comment.
> Are there any pieces of information that you need not provided by the
> upiu tracer?
> 
> Thanks,
> Avri

In extreme cases, when the UFS runs into bad state, system may crash. 
There may not be a chance to collect trace. If trace is not collected 
and failure is hard to be reproduced, some command logs prints would be 
very helpful to help understand what was going on before we run into 
failure.

Thanks,
Can Guo