From: Ulf Hansson <ulf.hansson@linaro.org>
To: Sarthak Garg <quic_sartgarg@quicinc.com>
Cc: Andy Gross <agross@kernel.org>,
Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
Adrian Hunter <adrian.hunter@intel.com>,
linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-msm@vger.kernel.org, quic_cang@quicinc.com,
quic_nguyenb@quicinc.com, quic_rampraka@quicinc.com,
quic_pragalla@quicinc.com, quic_sayalil@quicinc.com,
quic_nitirawa@quicinc.com, quic_sachgupt@quicinc.com,
quic_bhaskarv@quicinc.com, quic_narepall@quicinc.com,
kernel@quicinc.com,
Veerabhadrarao Badiganti <quic_vbadigan@quicinc.com>
Subject: Re: [PATCH V3 1/3] mmc: core: Add partial initialization support
Date: Fri, 27 Oct 2023 11:53:26 +0200 [thread overview]
Message-ID: <CAPDyKFrVNfqUxU2iGEDXrshOEKm1KROCHTPpSyDAgZPMPojfsg@mail.gmail.com> (raw)
In-Reply-To: <21208de0-79bc-42c7-b32f-355daf5b09f0@quicinc.com>
[...]
> >> +{
> >> + int err = 0;
> >> + struct mmc_card *card = host->card;
> >> +
> >> + mmc_set_bus_width(host, host->cached_ios.bus_width);
> >> + mmc_set_timing(host, host->cached_ios.timing);
> >> + if (host->cached_ios.enhanced_strobe) {
> >> + host->ios.enhanced_strobe = true;
> >> + if (host->ops->hs400_enhanced_strobe)
> >> + host->ops->hs400_enhanced_strobe(host, &host->ios);
> >> + }
> >> + mmc_set_clock(host, host->cached_ios.clock);
> >> + mmc_set_bus_mode(host, host->cached_ios.bus_mode);
> >> +
> >
> > Rather than re-using the above APIs and the ->set_ios() callback in
> > the host, I believe it would be better to add a new host ops to manage
> > all of the above at once instead. Something along the lines of the
> > below, would then replace all of the above.
> >
> > host->ops->restore_ios(host, &host->cached_ios)
> > memcpy(&host->ios, &host->cached_ios, sizeof(host->ios));
> >
> > Would that make sense to you too?
> >
>
>
> I didn't get this completely. Do you mean that we should implement a new
> restore_ios callback (e.g. sdhci_restore_ios) similar to sdhci_set_ios
> and removing all the redundant code from sdhci_set_ios which should
> achieve the behaviour same as calling all the above mmc_set_* API's ?
Correct. Would it not simply the things in the driver too?
>
>
> >> + if (!mmc_card_hs400es(card) &&
> >> + (mmc_card_hs200(card) || mmc_card_hs400(card))) {
> >> + err = mmc_execute_tuning(card);
> >> + if (err) {
> >> + pr_err("%s: %s: Tuning failed (%d)\n",
> >> + mmc_hostname(host), __func__, err);
> >
> > There is already a print being done in mmc_execute_tuning() at
> > failure. So, let's drop the above print.
> >
>
> Sure will take care in V4.
>
> >> + goto out;
> >> + }
> >> + }
> >> +
> >> + err = mmc_test_awake_ext_csd(host);
> >
> > Again, I don't get why this is needed, so let's discuss this more.
> >
>
> This is just a safety check added because ext_csd has some W/E_P or
> W/C_P registers which gets reset if any HW reset happens to the card.
> So this will check for those cases if any other vendor is doing reset as
> part of suspend and compare a subset of those W/E_P and W/C_P registers
> and if they are changed then we will bail out of this partial init
> feature and go for full initialization.
> We are also fine with removing this function but just added for the
> above mentioned case.
In that case, I would rather remove it as I think it's superfluous.
More precisely, I would expect that we fail to wake up the card with a
CMD5 (get an error response for the CMD) if there has been a HW reset
somewhere done before.
Another reason to *not* read the ext_csd would be to further improve
the resume time, as reading it takes time too. I would be curious to
know how much though. :-)
[...]
Kind regards
Uffe
next prev parent reply other threads:[~2023-10-27 9:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-19 5:46 [PATCH V3 0/3] mmc: Add partial initialization support Sarthak Garg
2023-10-19 5:46 ` [PATCH V3 1/3] mmc: core: " Sarthak Garg
2023-10-19 15:00 ` Ulf Hansson
2023-10-27 8:41 ` Sarthak Garg
2023-10-27 9:53 ` Ulf Hansson [this message]
2024-01-29 6:50 ` Sarthak Garg
2023-10-19 5:46 ` [PATCH V3 2/3] mmc: sdhci-msm: Enable MMC_CAP_AGGRESSIVE_PM for Qualcomm controllers Sarthak Garg
2023-10-19 5:46 ` [PATCH V3 3/3] mmc: sdhci-msm: Enable MMC_CAP2_SLEEP_AWAKE " Sarthak Garg
-- strict thread matches above, loose matches on Subject: below --
2023-10-17 6:13 [PATCH V3 0/3] mmc: Add partial initialization support Sarthak Garg
2023-10-17 6:13 ` [PATCH V3 1/3] mmc: core: " Sarthak Garg
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