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

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Date:   Tue, 10 Mar 2020 18:09:10 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Sowjanya Komatineni <skomatineni@...dia.com>
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

[...]

> >>>
> >>> 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