linux-kernel - RE: Re: [PATCH v31 2/4] scsi: ufs: L2P map management for HPB read

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Date:   Tue, 23 Mar 2021 14:37:31 +0900
From:   Daejun Park <daejun7.park@...sung.com>
To:     Can Guo <cang@...eaurora.org>, Bean Huo <huobean@...il.com>
CC:     Daejun Park <daejun7.park@...sung.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        "avri.altman@....com" <avri.altman@....com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        ALIM AKHTAR <alim.akhtar@...sung.com>,
        JinHwan Park <jh.i.park@...sung.com>,
        Javier Gonzalez <javier.gonz@...sung.com>,
        Sung-Jun Park <sungjun07.park@...sung.com>,
        Jinyoung CHOI <j-young.choi@...sung.com>,
        Dukhyun Kwon <d_hyun.kwon@...sung.com>,
        Keoseong Park <keosung.park@...sung.com>,
        Jaemyung Lee <jaemyung.lee@...sung.com>,
        Jieon Seol <jieon.seol@...sung.com>
Subject: RE: Re: [PATCH v31 2/4] scsi: ufs: L2P map management for HPB read

>On 2021-03-23 12:22, Can Guo wrote:
>> On 2021-03-22 17:11, Bean Huo wrote:
>>> On Mon, 2021-03-22 at 15:54 +0900, Daejun Park wrote:
>>>> +       switch (rsp_field->hpb_op) {
>>>> 
>>>> +       case HPB_RSP_REQ_REGION_UPDATE:
>>>> 
>>>> +               if (data_seg_len != DEV_DATA_SEG_LEN)
>>>> 
>>>> +                       dev_warn(&hpb->sdev_ufs_lu->sdev_dev,
>>>> 
>>>> +                                "%s: data seg length is not
>>>> same.\n",
>>>> 
>>>> +                                __func__);
>>>> 
>>>> +               ufshpb_rsp_req_region_update(hpb, rsp_field);
>>>> 
>>>> +               break;
>>>> 
>>>> +       case HPB_RSP_DEV_RESET:
>>>> 
>>>> +               dev_warn(&hpb->sdev_ufs_lu->sdev_dev,
>>>> 
>>>> +                        "UFS device lost HPB information during
>>>> PM.\n");
>>>> 
>>>> +               break;
>>> 
>>> Hi Deajun,
>>> This series looks good to me. Just here I have one question. You 
>>> didn't
>>> handle HPB_RSP_DEV_RESET, just a warning.  Based on your SS UFS, how 
>>> to
>>> handle HPB_RSP_DEV_RESET from the host side? Do you think we shoud
>>> reset host side HPB entry as well or what else?
>>> 
>>> 
>>> Bean
>> 
>> Same question here - I am still collecting feedbacks from flash vendors 
>> about
>> what is recommanded host behavior on reception of HPB Op code 0x2, 
>> since it
>> is not cleared defined in HPB2.0 specs.
>> 
>> Can Guo.
> 
>I think the question should be asked in the HPB2.0 patch, since in 
>HPB1.0 device
>control mode, a HPB reset in device side does not impact anything in 
>host side -
>host is not writing back any HPB entries to device anyways and HPB Read 
>cmd with
>invalid HPB entries shall be treated as normal Read(10) cmd without any 
>problems.

Yes, UFS device will process read command even the HPB entries are valid or
not. So it is warning about read performance drop by dev reset.

Thanks,
Daejun

>Please correct me if I am wrong.



>Thanks,
>Can Guo.
> 
> 
>