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Subject: Re: [PATCH v3 5/5] Revert "scsi: ufs: disable vccq if it's not needed
 by UFS device"
To:     Alim Akhtar <alim.akhtar@samsung.com>,
        Marc Gonzalez <marc.w.gonzalez@free.fr>,
        MSM <linux-arm-msm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Andy Gross <andy.gross@linaro.org>,
        David Brown <david.brown@linaro.org>,
        Evan Green <evgreen@chromium.org>,
        Douglas Anderson <dianders@chromium.org>,
        Avri Altman <avri.altman@wdc.com>,
        Pedro Sousa <pedrom.sousa@synopsys.com>,
        Subhash Jadavani <subhashj@codeaurora.org>,
        Bart Van Assche <bvanassche@acm.org>,
        SCSI <linux-scsi@vger.kernel.org>, Hannes Reinecke <hare@suse.de>
References: <e3c82a49-c601-effc-348f-f768656c659f@free.fr>
 <CGME20190204174549epcas4p4682667176f55101f69cc24cc455c9f3c@epcas4p4.samsung.com>
 <70618c25-83f0-b9db-51a3-c1d74b605a45@free.fr>
 <5f2a8378-1f22-6a52-356d-56d3b393ab1d@samsung.com>
 <05d2d193-4181-12ce-b4fb-4e8dec5aef27@free.fr>
 <7610c262-1451-9bb2-48a6-4daf6f534f6c@free.fr>
 <42c86292-22e9-4c5e-d64d-bc6107af45bf@free.fr>
 <740e6332-b54f-ab62-915a-0aec6be450d3@samsung.com>
 <2a59c11a-037f-c8c3-235a-9b21183a0801@free.fr>
 <90f24b35-89b0-cea0-1ab3-13c2a419b138@samsung.com>
 <81b85f39-49b5-901b-ec79-19708509965e@codeaurora.org>
 <2c0e5f03-0bb8-e5db-b5de-790da439fcfe@samsung.com>
From:   Jeffrey Hugo <jhugo@codeaurora.org>
Message-ID: <349da668-6bb5-fcf4-c3f2-f7f7e113ed67@codeaurora.org>
Date:   Fri, 8 Feb 2019 07:59:57 -0700
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On 2/8/2019 2:09 AM, Alim Akhtar wrote:
> Hi Jeffrey,
> 
> On 07/02/19 8:22 PM, Jeffrey Hugo wrote:
>> On 2/7/2019 1:50 AM, Alim Akhtar wrote:
>>> Hi Marc,
>>>
>>> On 06/02/19 9:22 PM, Marc Gonzalez wrote:
>>>> On 06/02/2019 16:27, Alim Akhtar wrote:
>>>>
>>>>> On 06/02/19 8:29 PM, Marc Gonzalez wrote:
>>>>>
>>>>>> [    2.405734] regulator_disable: ENTER vdd_l26
>>>>>> [    2.405958] regulator_disable: EXIT vdd_l26
>>>>>> [    2.406032]   regulator_set_load: vdd_l26 = 0 uA
>>>>>> [    3.930447] ufshcd-qcom 1da4000.ufshc: ufshcd_query_attr: opcode
>>>>>> 0x04 for idn 13 failed, index 0, err = -11
>>>>>> [    5.434358] ufshcd-qcom 1da4000.ufshc: ufshcd_query_attr: opcode
>>>>>> 0x04 for idn 13 failed, index 0, err = -11
>>>>>> [    6.938318] ufshcd-qcom 1da4000.ufshc: ufshcd_query_attr: opcode
>>>>>> 0x04 for idn 13 failed, index 0, err = -11
>>>>>> [    6.938414] ufshcd-qcom 1da4000.ufshc: ufshcd_query_attr_retry:
>>>>>> query attribute, idn 13, failed with error -11 after 3 retires
>>>>>> [    6.946959] ufshcd-qcom 1da4000.ufshc:
>>>>>> ufshcd_disable_auto_bkops: failed to enable exception event -11
>>>>>> [    6.958523] ufshcd-qcom 1da4000.ufshc: dme-peer-get: attr-id
>>>>>> 0x1587 failed 3 retries
>>>>>> [    6.967730] ufshcd-qcom 1da4000.ufshc: dme-peer-get: attr-id
>>>>>> 0x1586 failed 3 retries
>>>>>> [    6.975576] ufshcd-qcom 1da4000.ufshc: ufshcd_get_max_pwr_mode:
>>>>>> invalid max pwm tx gear read = 0
>>>>>> [    6.983306] ufshcd-qcom 1da4000.ufshc: ufshcd_probe_hba: Failed
>>>>>> getting max supported power mode
>>>>>> [    8.506314] ufshcd-qcom 1da4000.ufshc: ufshcd_query_flag:
>>>>>> Sending flag query for idn 3 failed, err = -11
>>>>>> [   10.010352] ufshcd-qcom 1da4000.ufshc: ufshcd_query_flag:
>>>>>> Sending flag query for idn 3 failed, err = -11
>>>>>> [   11.514313] ufshcd-qcom 1da4000.ufshc: ufshcd_query_flag:
>>>>>> Sending flag query for idn 3 failed, err = -11
>>>>>> [   11.514412] ufshcd-qcom 1da4000.ufshc: ufshcd_query_flag_retry:
>>>>>> query attribute, opcode 5, idn 3, failed with error -11 after 3
>>>>>> retires
>>>>>> [   13.050354] ufshcd-qcom 1da4000.ufshc:
>>>>>> __ufshcd_query_descriptor: opcode 0x01 for idn 8 failed, index 0,
>>>>>> err = -11
>>>>>> [   14.554313] ufshcd-qcom 1da4000.ufshc:
>>>>>> __ufshcd_query_descriptor: opcode 0x01 for idn 8 failed, index 0,
>>>>>> err = -11
>>>>>> [   16.058313] ufshcd-qcom 1da4000.ufshc:
>>>>>> __ufshcd_query_descriptor: opcode 0x01 for idn 8 failed, index 0,
>>>>>> err = -11
>>>>>> [   16.058421] ufshcd-qcom 1da4000.ufshc: ufshcd_read_desc_param:
>>>>>> Failed reading descriptor. desc_id 8, desc_index 0, param_offset 0,
>>>>>> ret -11
>>>>>> [   16.067654] ufshcd-qcom 1da4000.ufshc: ufshcd_init_icc_levels:
>>>>>> Failed reading power descriptor.len = 98 ret = -11
>>>>>> [   37.074334] ufshcd-qcom 1da4000.ufshc: link startup failed 1
>>>>>
>>>>> Can you check if your UFS device RESET_N is asserted correctly. It
>>>>> might
>>>>> be connected to some regulator and may be you can try keeping that
>>>>> regulator as "regulator-always-on" from your DT node.
>>>>
>>>> How do I check RESET_N? In software or hardware?
>>>>
>>> RST_N is the reset logic for UFS device core logic and it is input to
>>> the device from UFS host controller.So, in your platform please check if
>>> this line somehow connected to (pulled up) a PMIC supply. If that is the
>>> case, please keep that regulator ON and see if this issue is resolved.
>>
>> The reset line is routed though the global clock controller (GCC), and
>> must be explicitly asserted within the GCC to trigger a reset.  As far
>> as I am aware, Linux is not touching this.
>>
>> Additionally, I fail to see how if this was a reset issue, reverting
>> 60f0187031c0 would have any impact (which doing so addresses our issue)
>>
> OK, that's again implementation dependent and your platform used that
> way. My point was to make sure that reset part is ok, if reset/power is
> not proper to the UFS device core logic this kind of issues comes.

We are following the Hardware Programming Guide written by the platform 
designers with regard to UFS, including the reset logic.  I really don't 
think the reset logic is an issue here.

> 
>>>> Do you think it is not a good idea to revert
>>>> 60f0187031c05e04cbadffb62f557d0ff3564490 ?
>>>>
>>> Please hold on till we understand the real cause of this issue. Or we
>>> have a consensuses for reverting the said commit.
>>> Thanks!
>>
>> Did you see https://lkml.org/lkml/2019/2/5/659 where I indicated VCCQ
>> powers components within the host controller, and by not setting load on
>> the regulator properly, we are likely undervolting those components due
>> to the current draw?
>>
> In theory may be true. But looks like we dont have a solid evidence yet
> (correct me if I am wrong or misunderstood anything here
The evidence seems simple.  We have properly described in DT all the 
regulators that are consumed by the UFS host controller, and by 
extension, the UFS storage chip as well.

By default, with no kernel changes, UFS does not work.

Marc and I debugged the issue, and found that the VCCQ regulator was not 
being handled properly, and reverting the change we are discussing fixes 
the the VCCQ regulator issue, and as a result UFS works.

Again, despite the fact that we may have a Samsung UFS storage chip, 
which triggers the quirk, the UFS host controller which talks to that 
chip requires VCCQ, therefore this quirk breaks us.

> So that means its some short of hardware/board quirk, right?

No

> Can you please recheck the schematic and see what Bjorn is telling
> (about having right entries in the DT for regulator) resolve your issue?

Already done.  The schematic defines vcc, vccq, and vccq2.  All of those 
are listed in DT, and have been since Marc and I have been trying to 
utilize UFS.

> 
> Marc, Can you disabled pmic on that board (hope your board boots with
> default PMIC supply) and see if this issue still occurs?

The PMIC is required the boot the board.  I doubt the board will be 
functional with the PMIC disabled.

> I am just trying to understand and see what is the real cause.

Our analysis is that VCCQ is required and 
60f0187031c05e04cbadffb62f557d0ff3564490 prevents the proper 
configuration of VCCQ, thus a required resource (VCCQ) is not in the 
proper state.

> 
> @Yaniv Gardi, will you be able to comment on reason for adding
> 60f0187031c05e04cbadffb62f557d0ff3564490 (any issue faced)?
> 


-- 
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm 
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.