From: Chunyan Zhang <zhang.lyra@gmail.com>
To: Baolin Wang <baolin.wang@linaro.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Orson Zhai <orsonzhai@gmail.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming
Date: Tue, 23 Jul 2019 11:21:03 +0800 [thread overview]
Message-ID: <CAAfSe-s=Lae-JV_ogAyd355U6X2q0Zr-fhHcMm1=y=So=UTpxw@mail.gmail.com> (raw)
In-Reply-To: <CAMz4kuKraOb_o0LFWnqkS7m0Xd3QGrw1P+md0YBNbbbp1967OA@mail.gmail.com>
On Tue, 23 Jul 2019 at 11:05, Baolin Wang <baolin.wang@linaro.org> wrote:
>
> Hi Ulf,
>
> On Mon, 22 Jul 2019 at 19:54, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >
> > On Wed, 17 Jul 2019 at 04:29, Baolin Wang <baolin.wang@linaro.org> wrote:
> > >
> > > In sdhci_runtime_resume_host() function, we will always do software reset
> > > for all, which will cause Spreadtrum host controller work abnormally after
> > > resuming.
> >
> > What does "software reset for all" means?
>
> The SD host controller specification defines 3 types software reset:
> software reset for data line, software reset for command line and
> software reset for all.
> Software reset for all means this reset affects the entire Host
> controller except for the card detection circuit.
>
> >
> > >
> > > Thus for Spreadtrum platform that will not power down the SD/eMMC card during
> > > runtime suspend, we should not do software reset for all.
> >
> > Normally, sdhci hosts that enters runtime suspend doesn't power off
> > the card (there are some exceptions like PCI variants).
>
> Yes, same as our controller.
>
> >
> > So, what's so special here and how does the reset come into play? I
> > don't see sdhci doing a reset in sdhci_runtime_suspend|resume_host()
> > and nor doesn the callback from the sdhci-sprd.c variant doing it.
>
> In sdhci_runtime_resume_host(), it will issue sdhci_init(host, 0) to
> issue software reset for all.
>
> >
> > > To fix this
> > > issue, adding a specific reset operation that adds one condition to validate
> > > the power mode to decide if we can do software reset for all or just reset
> > > command and data lines.
> > >
> > > Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> > > ---
> > > Changess from v3:
> > > - Use ios.power_mode to validate if the card is power down or not.
> > >
> > > Changes from v2:
> > > - Simplify the sdhci_sprd_reset() by issuing sdhci_reset().
> > >
> > > Changes from v1:
> > > - Add a specific reset operation instead of changing the core to avoid
> > > affecting other hardware.
> > > ---
> > > drivers/mmc/host/sdhci-sprd.c | 19 ++++++++++++++++++-
> > > 1 file changed, 18 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/mmc/host/sdhci-sprd.c b/drivers/mmc/host/sdhci-sprd.c
> > > index 603a5d9..94f9726 100644
> > > --- a/drivers/mmc/host/sdhci-sprd.c
> > > +++ b/drivers/mmc/host/sdhci-sprd.c
> > > @@ -373,6 +373,23 @@ static unsigned int sdhci_sprd_get_max_timeout_count(struct sdhci_host *host)
> > > return 1 << 31;
> > > }
> > >
> > > +static void sdhci_sprd_reset(struct sdhci_host *host, u8 mask)
> > > +{
> > > + struct mmc_host *mmc = host->mmc;
> > > +
> > > + /*
> > > + * When try to reset controller after runtime suspend, we should not
> > > + * reset for all if the SD/eMMC card is not power down, just reset
> > > + * command and data lines instead. Otherwise will meet some strange
> > > + * behaviors for Spreadtrum host controller.
> > > + */
> > > + if (host->runtime_suspended && (mask & SDHCI_RESET_ALL) &&
> > > + mmc->ios.power_mode == MMC_POWER_ON)
> > > + mask = SDHCI_RESET_CMD | SDHCI_RESET_DATA;
> >
> > Can sdhci_sprd_reset() be called when the host is runtime suspended?
>
> When host tries to runtime resume in sdhci_runtime_resume_host(), it
> will call reset operation to do software reset.
>
> > That sounds like a bug to me, no?
>
> Since our controller will meet some strange behaviors if we do
> software reset for all in sdhci_runtime_resume_host(), and try to
> avoid changing the core logic of sdhci_runtime_resume_host() used by
> other hardware controllers, thus I introduced a specific reset ops and
> added some condition to make sure we just do software reset command
> and data lines from runtime suspend state.
I can make a verification on sprd's SC9863A, but that would take a
little time, since I need to make sd card registered with sdhci-sprd.c
first :)
Thanks,
Chunyan
next prev parent reply other threads:[~2019-07-23 3:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 2:28 [PATCH v4] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming Baolin Wang
2019-07-17 6:07 ` Adrian Hunter
2019-07-22 11:54 ` Ulf Hansson
2019-07-23 3:05 ` Baolin Wang
2019-07-23 3:21 ` Chunyan Zhang [this message]
2019-07-23 3:30 ` Baolin Wang
2019-07-23 12:38 ` Ulf Hansson
2019-07-24 2:21 ` Baolin Wang
2019-07-24 12:55 ` Adrian Hunter
2019-07-25 3:05 ` Baolin Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAAfSe-s=Lae-JV_ogAyd355U6X2q0Zr-fhHcMm1=y=So=UTpxw@mail.gmail.com' \
--to=zhang.lyra@gmail.com \
--cc=adrian.hunter@intel.com \
--cc=baolin.wang@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=orsonzhai@gmail.com \
--cc=ulf.hansson@linaro.org \
--cc=vincent.guittot@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).