From: Marek Vasut <marex@denx.de>
To: Shawn Guo <shawn.guo@linaro.org>
Subject: Re: [PATCH RFC] ARM: dts: mxs: leave card detect out of common mmc pins config
Date: Mon, 8 Apr 2013 18:28:26 +0200
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Cc: Hector Palacios <hector.palacios@digi.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "maxime.ripard@free-electrons.com" <maxime.ripard@free-electrons.com>,
        "fabio.estevam@freescale.com" <fabio.estevam@freescale.com>
References: <1365415940-11609-1-git-send-email-hector.palacios@digi.com> <5162CCED.4070707@digi.com> <20130408145019.GD5044@S2101-09.ap.freescale.net>
In-Reply-To: <20130408145019.GD5044@S2101-09.ap.freescale.net>
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Dear Shawn Guo,

> On Mon, Apr 08, 2013 at 03:58:05PM +0200, Hector Palacios wrote:
> > On 04/08/2013 02:48 PM, Shawn Guo wrote:
> > >On Mon, Apr 08, 2013 at 12:12:20PM +0200, Hector Palacios wrote:
> > >>MicroSD card sockets don't usually have card detect line. This pin
> > >>is actually not needed for the MMC to work and it is more of a
> > >>platform design decission to have it.
> > >>The card detect pin already has a configuration entry of its own:
> > >>'mmc0_cd_cfg' so we complete the iomux configuration here and let
> > >>platforms to include it or not depending on whether the card detect
> > >>line is routed to the SD socket.
> > >
> > >Sounds sensible.
> > >
> > >>Signed-off-by: Hector Palacios <hector.palacios@digi.com>
> > >>---
> > >>
> > >>Hello,
> > >>
> > >>All imx28 based platforms except 'bluegiga,apx4devkit' and
> > >>'schulercontrol,imx28-sps1', use 'mmc0_cd_cfg' in their mmc
> > >>configuration so please check whether this patch would break these
> > >>platforms.
> > >
> > >I just tested the patch on imx28-evk and card-detection still works.  So
> > >patches applied, thanks.
> > 
> > The EVK and most platforms will work because they are using
> > 'mmc0_cd_cfg' so actually this patch does not change anything on
> > them.
> > Platforms 'bluegiga,apx4devkit' and 'schulercontrol,imx28-sps1'
> > however are not referencing 'mmc0_cd_cfg' so after applying this
> > patch they will have unconfigured CD line and they may break.
> 
> Ah, yes.  I thought that any board that has CD support has to reference
> 'mmc0_cd_cfg'.  That's not necessarily true.
> 
> > The driver will call get_cd() upon probing, which returns the status of
> > the CD line. Please check these two platforms before applying.
> 
> Ok, let's wait for people owning the boards to confirm.

Maybe you want to use MMC_CAP_NEEDS_POLL as was noted by someone before on the 
olinuxino -- the slot is there, it's just the CD line that's missing.

Best regards,
Marek Vasut
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