linux-kernel - Re: [PATCH 3/4] scsi: ufs-debugfs: Add user-defined exception_event

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Message-ID: <b7a812ed-8965-76cf-3d05-be2486fcaed2@intel.com>
Date:   Wed, 3 Feb 2021 11:56:05 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Bean Huo <huobean@...il.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Can Guo <cang@...eaurora.org>,
        Stanley Chu <stanley.chu@...iatek.com>
Subject: Re: [PATCH 3/4] scsi: ufs-debugfs: Add user-defined
 exception_event_mask

On 3/02/21 11:45 am, Bean Huo wrote:
> On Tue, 2021-01-19 at 16:15 +0200, Adrian Hunter wrote:
>> Allow users to enable specific exception events via debugfs.
>>
>> The bits enabled by the driver ee_drv_ctrl are separated from the
>> bits
>> enabled by the user ee_usr_ctrl. The control mask ee_mask_ctrl is the
>> logical-or of those two. A mutex is needed to ensure that the masks
>> match
>> what was written to the device.
> 
> Hallo Adrian

Hi Bean

Thanks for the review

> 
> Would you like sharing the advantage of this debugfs node comparing to
> sysfs node "attributes/exception_event_control(if it is writable)"?

Primarily this is being done as a debug interface, but the user's exception
events also need to be kept separate from the driver's ones.

> what is the value of this?

To be able to determine if the UFS device is being affected by exception events.

> Also, now I can disable/enable UFS event over ufs-bsg.

That will be overwritten by the driver when it updates the e.g. bkops
control, or sometimes also suspend/resume.