[PATCH 3/3 v2] mmc: Add ESDHC weird voltage bits workaround

[Zang Roy-R61911]

> -----Original Message-----
> From: Anton Vorontsov [mailto:cbouatmailru at gmail.com] 
> Sent: Friday, July 30, 2010 15:06 PM
> To: Zang Roy-R61911
> Cc: linux-mmc at vger.kernel.org; linuxppc-dev at ozlabs.org; 
> akpm at linux-foundation.org
> Subject: Re: [PATCH 3/3 v2] mmc: Add ESDHC weird voltage bits 
> workaround
> 
> On Fri, Jul 30, 2010 at 11:52:57AM +0800, Roy Zang wrote:
> > P4080 ESDHC controller does not support 1.8V and 3.0V 
> voltage. but the
> > host controller capabilities register wrongly set the bits.
> > This patch adds the workaround to correct the weird voltage 
> setting bits.
> > 
> > Signed-off-by: Roy Zang <tie-fei.zang at freescale.com>
> > ---
> [...]
> > diff --git a/drivers/mmc/host/sdhci-of-core.c 
> b/drivers/mmc/host/sdhci-of-core.c
> > index 0c30242..1f3913d 100644
> > --- a/drivers/mmc/host/sdhci-of-core.c
> > +++ b/drivers/mmc/host/sdhci-of-core.c
> > @@ -164,6 +164,10 @@ static int __devinit 
> sdhci_of_probe(struct of_device *ofdev,
> >  	if (sdhci_of_wp_inverted(np))
> >  		host->quirks |= SDHCI_QUIRK_INVERTED_WRITE_PROTECT;
> >  
> > +	if (of_device_is_compatible(np, "fsl,p4080-esdhc"))
> > +		host->quirks |= (SDHCI_QUIRK_QORIQ_NO_VDD_180
> > +				|SDHCI_QUIRK_QORIQ_NO_VDD_300);
> > +
> 
> It should be two properties, something like sdhci,no-vdd-180
> and sdhci,no-vdd-300. But it might be even better: we have
> voltage-ranges for mmc-spi case, see
> Documentation/powerpc/dts-bindings/mmc-spi-slot.txt.
> 
> If voltage-ranges specified, then we use it, not capabilities
> register.
> 
> For p4080 it will be 'voltage-ranges = <3200 3400>;'. So, with
> voltage-ranges we can do fine grained VDD control without
> introducing anything new.
why not
               voltage-ranges = <3300 3300>;
?
Roy