linux-kernel - Re: [PATCH RESEND v2] scsi: ufs: clear doorbell for hibern8 errors when using ah8

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Date:   Mon, 25 Oct 2021 08:38:40 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Kiwoong Kim <kwmad.kim@...sung.com>, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, alim.akhtar@...sung.com,
        avri.altman@....com, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, beanhuo@...ron.com,
        cang@...eaurora.org, sc.suh@...sung.com, hy50.seo@...sung.com,
        sh425.lee@...sung.com, bhoon95.kim@...sung.com,
        vkumar.1997@...sung.com
Cc:     Bart Van Assche <bvanassche@....org>
Subject: Re: [PATCH RESEND v2] scsi: ufs: clear doorbell for hibern8 errors
 when using ah8

On 21/10/2021 14:04, Kiwoong Kim wrote:
>> On 19/10/2021 07:57, Kiwoong Kim wrote:
>>> Changes from v1:
>>> * Change the time to requeue pended commands
>>>
>>> When an scsi command is dispatched right after host complete all the
>>> pended requests and ufs driver tries to ring a doorbell, host might be
>>> still during entering into hibern8.
>>> If the hibern8 error occurrs during that period, the doorbell might
>>> not be zero and clearing it should have done.
>>> But, current ufshcd_err_handler goes directly to reset w/o clearing
>>> the doorbell when the driver's link state is broken.
>>
>> So you mean HCE 1->0 does not clear the doorbell register?
>>
>>> This patch is to requeue pended commands after host reset.
>>
>> So you mean HCE 0->1 does clear the doorbell register?
> 
> 
> I talked about this again and maybe he didn't seem to accept its description like that
> Because he just focused on the term 'disable' in the description.
> Instead, there is an vendor sfr to clear all the contexts.
> 
> Yes, the description contains like this, but I think he could think it's done when setting one.
> --
> When HCE is ‘0’ and software writes ‘1’, the host 
> controller hardware shall execute the step 2 described in 7.1.1 of this standard, 
> including >>>>> reset <<<<< of the host UTP and UIC layers.
> 
> Of course, some statements, such as 8.2.2. UIC Error Handling, seems to show setting zero means clearing.
> But speaking the description, it's not quite clear to me.
> 
> Anyway, let me know how to deal with this.

It seems vendor-specific.  Perhaps export ufshcd_complete_requests()
and call it from vendor ops->hce_enable_notify(hba, POST_CHANGE) ?

Note that Bart submitted a patch to remove ufshcd_retry_aborted_requests().