From: Ulf Hansson <ulf.hansson@linaro.org>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: Chris Ruehl <chris.ruehl@gtsys.com.hk>,
Adrian Hunter <adrian.hunter@intel.com>,
Haibo Chen <haibo.chen@nxp.com>,
Rob Herring <robh+dt@kernel.org>,
NXP Linux Team <linux-imx@nxp.com>,
Sascha Hauer <kernel@pengutronix.de>,
linux-mmc <linux-mmc@vger.kernel.org>,
DTML <devicetree@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 3/3] mmc: core: add support for disabling HS400 mode via DT
Date: Tue, 11 May 2021 14:19:36 +0200 [thread overview]
Message-ID: <CAPDyKFpii+q+oLqtt7he+qjqyzeUY39Oy0Wqq4cn5rXfEB6KiA@mail.gmail.com> (raw)
In-Reply-To: <0aa51fabade743fbaac70a149a771f37e7d05165.camel@pengutronix.de>
On Tue, 11 May 2021 at 13:54, Lucas Stach <l.stach@pengutronix.de> wrote:
>
> Hi Ulf,
>
> Am Dienstag, dem 11.05.2021 um 13:14 +0200 schrieb Ulf Hansson:
> > + Chris Ruehl
> >
> > On Mon, 10 May 2021 at 21:04, Lucas Stach <l.stach@pengutronix.de> wrote:
> > >
> > > From: Lucas Stach <dev@lynxeye.de>
> > >
> > > On some boards the data strobe line isn't wired up, rendering HS400
> > > support broken, even if both the controller and the eMMC claim to
> > > support it. Allow to disable HS400 mode via DT.
> >
> > Before I review the series, I just wanted to highlight that quite
> > recently we got a related series posted from Chris [1]. I made some
> > comments, but he hasn't replied yet.
> >
> > In any case, if I understood it correctly, it looks like some
> > controllers may support HS400 ES, but not HS200. Could that be the
> > case here as well? Or is this a different problem?
> >
> >
> That's not the issue I'm trying to solve here. HS400 modes, whether ES
> nor not, require the data strobe line to work. ES mode just defines how
> this line is used. I know for a fact that the board I'm dealing with
> here, just hasn't wired up this line between the SoC and the eMMC. Thus
> HS400 modes fail to work, even though both controller and eMMC support
> this mode.
>
> When HS400 is disabled, like in this series, communication falls back
> to HS200 mode and works fine this way.
Alright, thanks for clarifying. I will look into the series soon.
Kind regards
Uffe
>
> Regards,
> Lucas
>
> > Kind regards
> > Uffe
> >
> > [1]
> > https://patchwork.kernel.org/project/linux-mmc/patch/20201208061839.21163-7-chris.ruehl@gtsys.com.hk/
> >
> > >
> > > Signed-off-by: Lucas Stach <dev@lynxeye.de>
> > > ---
> > > v2:
> > > - move to core
> > > - actually disable all HS400 modes
> > > ---
> > > drivers/mmc/core/host.c | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> > > index 9b89a91b6b47..0e066c5f5243 100644
> > > --- a/drivers/mmc/core/host.c
> > > +++ b/drivers/mmc/core/host.c
> > > @@ -351,6 +351,9 @@ int mmc_of_parse(struct mmc_host *host)
> > > host->caps2 |= MMC_CAP2_NO_SD;
> > > if (device_property_read_bool(dev, "no-mmc"))
> > > host->caps2 |= MMC_CAP2_NO_MMC;
> > > + if (device_property_read_bool(dev, "no-mmc-hs400"))
> > > + host->caps2 &= ~(MMC_CAP2_HS400_1_8V | MMC_CAP2_HS400_1_2V |
> > > + MMC_CAP2_HS400_ES);
> > >
> > > /* Must be after "non-removable" check */
> > > if (device_property_read_u32(dev, "fixed-emmc-driver-type", &drv_type) == 0) {
> > > --
> > > 2.31.1
> > >
>
>
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next prev parent reply other threads:[~2021-05-11 13:21 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 19:03 [PATCH v2 1/3] dt-bindings: mmc: add no-mmc-hs400 flag Lucas Stach
2021-05-10 19:03 ` [PATCH v2 2/3] mmc: sdhci-esdhc-imx: advertise HS400 mode through MMC caps Lucas Stach
2021-05-11 3:00 ` Bough Chen
2021-05-11 8:18 ` Lucas Stach
2021-05-11 12:40 ` Adrian Hunter
2021-05-12 2:23 ` Bough Chen
2021-05-24 14:10 ` Ulf Hansson
2021-05-10 19:04 ` [PATCH v2 3/3] mmc: core: add support for disabling HS400 mode via DT Lucas Stach
2021-05-11 11:14 ` Ulf Hansson
2021-05-11 11:54 ` Lucas Stach
2021-05-11 12:19 ` Ulf Hansson [this message]
2021-05-24 14:10 ` Ulf Hansson
2021-05-24 14:10 ` [PATCH v2 1/3] dt-bindings: mmc: add no-mmc-hs400 flag Ulf Hansson
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