linux-kernel - Re: LKFT: arm x15: mmc1: cache flush error -110

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Date:   Tue, 10 Mar 2020 16:10:08 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
CC:     Jon Hunter <jonathanh@...dia.com>,
        Bitan Biswas <bbiswas@...dia.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        Jens Axboe <axboe@...nel.dk>,
        Alexei Starovoitov <ast@...nel.org>,
        linux-block <linux-block@...r.kernel.org>,
        <lkft-triage@...ts.linaro.org>,
        open list <linux-kernel@...r.kernel.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        John Stultz <john.stultz@...aro.org>,
        Faiz Abbas <faiz_abbas@...com>,
        Thierry Reding <treding@...dia.com>,
        Anders Roxell <anders.roxell@...aro.org>,
        Kishon <kishon@...com>
Subject: Re: LKFT: arm x15: mmc1: cache flush error -110


On 3/10/20 2:59 PM, Sowjanya Komatineni wrote:
>
> On 3/10/20 10:27 AM, Sowjanya Komatineni wrote:
>>
>> On 3/10/20 10:09 AM, Ulf Hansson wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> [...]
>>>
>>>>>>> I would like to get the regression fixed asap, but I also would 
>>>>>>> like
>>>>>>> to avoid reverting patches, unless really necessary. May I 
>>>>>>> propose the
>>>>>>> following two options.
>>>>>>>
>>>>>>> 1. Find out why polling with ->card_busy() or CMD13, for a CMD6 
>>>>>>> with
>>>>>>> an R1 response doesn't work - and then fix that behaviour.
>>>>>>>
>>>>>>> 2. Set the mmc->max_busy_timeout to zero for sdhci-tegra, which 
>>>>>>> makes
>>>>>>> the core to always use R1B for CMD6 (and erase). This also means 
>>>>>>> that
>>>>>>> when the cmd->busy_timeout becomes longer than 11s, sdhci-tegra 
>>>>>>> must
>>>>>>> disable the HW busy timeout and just wait "forever".
>>>>>>>
>>>>>>> If you decide for 2, you can add the software timeout support on 
>>>>>>> top,
>>>>>>> but make that can be considered as a next step of an improvement,
>>>>>>> rather than needed as fix. Note that, I believe there are some 
>>>>>>> support
>>>>>>> for software timeout already in the sdhci core, maybe you need to
>>>>>>> tweak it a bit for your case, I don't know.
>>>>>>>
>>>>>>> Kind regards
>>>>>>> Uffe
>>>>>> Hi Uffe
>>>>>>
>>>>>> Will go with 2nd option and will send patches out when ready.
>>>>> Okay, good.
>>>>>
>>>>>> BTW, Tegra host also supports SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK 
>>>>>> for
>>>>>> data timeout based on host clock when using finite mode (HW busy
>>>>>> detection based on DATA TIMEOUT count value when cmd operation 
>>>>>> timeout
>>>>>> is < 11s for tegra host).
>>>>>>
>>>>>> So, looks like we cant set host max_busy_timeout to 0 for Tegra 
>>>>>> host to
>>>>>> force R1B during SWITCH and SLEEP_AWAKE.
>>>>>>
>>>>>> So, was thinking to introduce host capability 
>>>>>> MMC_CAP2_LONG_WAIT_HW_BUSY
>>>>>> which can be used for hosts supporting long or infinite HW busy wait
>>>>>> detection and will update mmc and mmc_ops drivers to not allow 
>>>>>> convert
>>>>>> R1B to R1B for hosts with this capability during SLEEP_AWAKE and 
>>>>>> SWITCH.
>>>>> That seems reasonable, it becomes probably both easier and clearer by
>>>>> adding a new host cap.
>>>>>
>>>>> In any case, let me help out and cook a patch for this for the core
>>>>> part (I leave the sdhci change to you). It may be a bit tricky,
>>>>> especially since I have currently queued a bunch of new changes for
>>>>> v5.7, that enables more users of mmc_poll_for_busy() in the core.
>>>>> Maybe I need to temporarily drop them, so we can fix these problems
>>>>> first. I will check.
>>>>>
>>>>> Probably, I would also name the cap MMC_CAP_HW_NEED_RSP_BUSY, as that
>>>>> seems to be describing the common problem we have for sdhci
>>>>> omap/tegra.
>>>>>
>>>>> Finally, it seems like MMC_CAP_WAIT_WHILE_BUSY should be set for
>>>>> sdhci- tegra, so while at it, perhaps you can cook a patch for 
>>>>> that as
>>>>> well.
>>>>>
>>>>> Kind regards
>>>>> Uffe
>>>> OK, I sent v1 yesterday. Please ignore them then.
>>> Oh, I haven't seen them. In any case, I am ignoring them.
>>>
>>>> Will send out patches only for HW busy wait modes program based on cmd
>>>> timeout and WAIT_WHILE_BUSY enabled.
>>> Great, thanks!
>>>
>>> Please help test the series I just posted as well, if you have the
>>> time ofcourse.
>>>
>>> Kind regards
>>> Uffe
>>
>> Sure,
>>
>> Thanks
>>
>> Sowjanya
>
>
> mmc_sleep() also needs update to force R1B when host sets capability 
> MMC_CAP_NEED_RSP_BUSY
>
>
Tested patches and they work good.