[PATCH RFC 2/3] mmc: core: add new cap for 3.3V only DDR MMCs

From: stefan.wahren@i2se.com (Stefan Wahren)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH RFC 2/3] mmc: core: add new cap for 3.3V only DDR MMCs
Date: Sat, 6 Aug 2016 16:18:25 +0200 (CEST)	[thread overview]
Message-ID: <16443443.114784.752d0f22-93a7-46e8-bb14-c884787aaea3.open-xchange@email.1und1.de> (raw)
In-Reply-To: <0e38d62a-b3d0-30ca-fca9-bb740ae54d0a@denx.de>

Hi Marek,

> Marek Vasut <marex@denx.de> hat am 6. August 2016 um 15:14 geschrieben:
> 
> 
> On 08/06/2016 02:55 PM, Stefan Wahren wrote:
> > This patch based on the work of Fabio Estevam:
> > "[PATCH v2] mmc: core: Do not set mmc voltage to 1.8V when
> > 'no-1-8-v' is present"
> > 
> > It adds the support for 3.3V only DDR MMC hosts.
> 
> Do such cards even exist ? Do you have a link where I can find some ?

i never said anything about SD cards. I mean eMMC modules which usually have 8
data pins like this one [1].

Please don't blame me if it's not compatible to i.MX28. It's only an example.

[1] -
http://datasheet.octopart.com/THGBM3G4D1FBAIGH2H-Toshiba-datasheet-20748880.pdf

> 
> > Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> > ---
> >  drivers/mmc/core/host.c  |    2 ++
> >  drivers/mmc/core/mmc.c   |    6 ++++++
> >  include/linux/mmc/host.h |    1 +
> >  3 files changed, 9 insertions(+)
> > 
> > Changes to Fabio's patch:
> > - rebase to current linux-next
> > - rename DT property to mmc-ddr-3_3v
> > - use EXT_CSD_CARD_TYPE_DDR_52 instead of new define
> > 
> > diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> > index 98f25ff..4c971de 100644
> > --- a/drivers/mmc/core/host.c
> > +++ b/drivers/mmc/core/host.c
> > @@ -301,6 +301,8 @@ int mmc_of_parse(struct mmc_host *host)
> >  	if (of_property_read_bool(np, "wakeup-source") ||
> >  	    of_property_read_bool(np, "enable-sdio-wakeup")) /* legacy */
> >  		host->pm_caps |= MMC_PM_WAKE_SDIO_IRQ;
> > +	if (of_property_read_bool(np, "mmc-ddr-3_3v"))
> > +		host->caps2 |= MMC_CAP2_3_3V_ONLY_DDR;
> >  	if (of_property_read_bool(np, "mmc-ddr-1_8v"))
> >  		host->caps |= MMC_CAP_1_8V_DDR;
> >  	if (of_property_read_bool(np, "mmc-ddr-1_2v"))
> > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> > index f2d185c..8a933d5 100644
> > --- a/drivers/mmc/core/mmc.c
> > +++ b/drivers/mmc/core/mmc.c
> > @@ -210,6 +210,12 @@ static void mmc_select_card_type(struct mmc_card *card)
> >  		avail_type |= EXT_CSD_CARD_TYPE_HS_52;
> >  	}
> >  
> > +	if (caps2 & MMC_CAP2_3_3V_ONLY_DDR &&
> > +	    card_type & EXT_CSD_CARD_TYPE_DDR_1_8V) {
> > +		hs_max_dtr = MMC_HIGH_DDR_MAX_DTR;
> > +		avail_type |= EXT_CSD_CARD_TYPE_DDR_52;
> > +	}
> > +
> >  	if (caps & MMC_CAP_1_8V_DDR &&
> >  	    card_type & EXT_CSD_CARD_TYPE_DDR_1_8V) {
> >  		hs_max_dtr = MMC_HIGH_DDR_MAX_DTR;
> > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> > index aa4bfbf..db0775d 100644
> > --- a/include/linux/mmc/host.h
> > +++ b/include/linux/mmc/host.h
> > @@ -311,6 +311,7 @@ struct mmc_host {
> >  #define MMC_CAP2_HS400_ES	(1 << 20)	/* Host supports enhanced strobe */
> >  #define MMC_CAP2_NO_SD		(1 << 21)	/* Do not send SD commands during
> > initialization */
> >  #define MMC_CAP2_NO_MMC		(1 << 22)	/* Do not send (e)MMC commands during
> > initialization */
> > +#define MMC_CAP2_3_3V_ONLY_DDR	(1 << 23)	/* Only supports 3.3V DDR */
> >  
> >  	mmc_pm_flag_t		pm_caps;	/* supported pm features */
> >  
> > 
> 
> 
> -- 
> Best regards,
> Marek Vasut