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

From: Can Guo <cang@codeaurora.org>
To: daejun7.park@samsung.com
Cc: Bean Huo <huobean@gmail.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	avri.altman@wdc.com, jejb@linux.ibm.com,
	martin.petersen@oracle.com, asutoshd@codeaurora.org,
	stanley.chu@mediatek.com, bvanassche@acm.org,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
	ALIM AKHTAR <alim.akhtar@samsung.com>,
	JinHwan Park <jh.i.park@samsung.com>,
	Javier Gonzalez <javier.gonz@samsung.com>,
	Sung-Jun Park <sungjun07.park@samsung.com>,
	Jinyoung CHOI <j-young.choi@samsung.com>,
	Dukhyun Kwon <d_hyun.kwon@samsung.com>,
	Keoseong Park <keosung.park@samsung.com>,
	Jaemyung Lee <jaemyung.lee@samsung.com>,
	Jieon Seol <jieon.seol@samsung.com>
Subject: Re: [PATCH v31 2/4] scsi: ufs: L2P map management for HPB read
Date: Tue, 23 Mar 2021 14:07:00 +0800	[thread overview]
Message-ID: <1df7bb51dc481c3141cdcf85105d3a5b@codeaurora.org> (raw)
In-Reply-To: <20210323053731epcms2p70788f357b546e9ca21248175a8884554@epcms2p7>

On 2021-03-23 13:37, Daejun Park wrote:
>> 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.

Yeah, but still I am 100% sure about what should host do in case of 
HPB2.0
when it receives HPB Op code 0x2, I am waiting for feedbacks.

Thanks,
Can Guo.

> 
> Thanks,
> Daejun
> 
>> Please correct me if I am wrong.
> 
> 
> 
>> Thanks,
>> Can Guo.
>> 
>> 
>> 