Re: [PATCH v4 3/6] ARM: vexpress: Add DT support for the motherboard

From: Pawel Moll <pawel.moll@arm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "devicetree-discuss@lists.ozlabs.org"
	<devicetree-discuss@lists.ozlabs.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v4 3/6] ARM: vexpress: Add DT support for the motherboard
Date: Thu, 08 Dec 2011 10:37:59 +0000	[thread overview]
Message-ID: <1323340679.32116.26.camel@hornet.cambridge.arm.com> (raw)
In-Reply-To: <47277884.EQ6QaTZjNt@wuerfel>

On Wed, 2011-12-07 at 22:49 +0000, Arnd Bergmann wrote:
> On Tuesday 06 December 2011 15:43:46 Pawel Moll wrote:
> > +
> > +static struct of_dev_auxdata v2m_dt_auxdata_lookup[] __initdata = {
> > +       OF_DEV_AUXDATA("arm,vexpress-flash", V2M_NOR0, "physmap-flash",
> > +                       &v2m_flash_data),
> > +       OF_DEV_AUXDATA("arm,primecell", V2M_MMCI, "mb:mmci", &v2m_mmci_data),
> > +       {}
> > +};
> 
> One more thing I noticed. While I'm not familiar with the progress on
> device driver conversion, 

I'm aware of these two last non-DT bits and actually already started
working on them, but this won't happen this year (I'm on holiday
starting next Friday without any access to Internet whatsoever :-)

> I think you should be using the physmap_of
> driver instead of physmap, which will remove the need for the
> platform data.

There's one bit missing in the physmap_of. The "set_vpp" handle which is
used on VE:

static struct physmap_flash_data v2m_flash_data = {
        .width          = 4,
        .set_vpp        = v2m_flash_set_vpp,
};      

My plan is to extend the physmap_of driver so it could operate VPP via
gpio API and make the sysreg a gpio controller, having Flash VPP, CF &
MMC card detects and DVI output control (that's for CLCD) as internal
GPIO lines.

> For mmci, it should not be hard to do change the driver so it
> understands the device tree, too. The easiest implementation for
> that would be to add some code into mmci_probe and allocate
> an mmci_platform_data structure that gets filled with the required
> attributes.

I've started the implementation already, but it turned out much trickier
that I was hoping... One thing is the "status" handle (card detect line
"virtual gpio" I mentioned above), the second problem is the fact that
mmci platform data can take generic caps MMC_CAP_* from
include/linux/mmc/host.h (now even caps2 as well)... This issue was
already briefly mentioned here:
http://article.gmane.org/gmane.linux.kernel.samsung-soc/7639 and as
there was no generic resolution my plan is to reuse as much properties
from other MMC host controllers and forge the missing one (as a superset
of ARM's and STE's cell implementations). But as I said, it's unlikely
to happen this year...

Cheers!

Paweł

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