Subject: Re: [PATCH 3/4 V2] mmc: esdhc: Add quirks to support T4240QDS board

From: Anton Vorontsov <[email-masked]>
Date: Mon, 15 Jul 2013 22:04:52 -0700

On Tue, Jul 16, 2013 at 03:11:47AM +0000, Zhang Haijun-B42677 wrote:
> Hi, Anton
> 
> You mean get voltage support from DTS?
> Or get voltage both from DTS and host capacity register?

The logic might be that you first check device-tree, if it specifies
voltage ranges, assume that DTS knows better, otherwise read capabilities
from the register.

Anton

> Thanks.
> 
> Regards
> Haijun.
> 
> 
> > -----Original Message-----
> > From: [email-masked] [mailto:linux-mmc-
> > [email-masked]] On Behalf Of Anton Vorontsov
> > Sent: Saturday, July 13, 2013 2:35 AM
> > To: Wood Scott-B07421
> > Cc: Zhang Haijun-B42677; [email-masked]; linuxppc-
> > [email-masked]; [email-masked]; Fleming Andy-AFLEMING; Wrobel
> > Heinz-R39252
> > Subject: Re: [PATCH 3/4 V2] mmc: esdhc: Add quirks to support T4240QDS
> > board
> > 
> > On Mon, Jul 08, 2013 at 12:18:39PM -0500, Scott Wood wrote:
> > > On 07/08/2013 02:16:04 AM, Haijun Zhang wrote:
> > > >On T4240QDS board controllers has an unusable ADMA engine, so use
> > > >SDMA instead.
> > > >Also 3.0v is support on T4240QDS board even if the capacity detailed
> > > >only 1.8v support. Without this quirk SD card will declare voltage
> > > >not support and
> > > >
> > > >Signed-off-by: Haijun Zhang <[email-masked]>
> > >
> > > ...and what?
> > >
> > > Why is this board-specific?  Isn't the controller part of the SoC, not
> > > part of the board?  If it really is board-specific, could you be more
> > > detailed about why (ideally with an erratum number), and check the
> > > toplevel board compatible (or get the information from platform
> > > code) rather than modify the device tree?
> > 
> > Yup, and if anything, I would recommend to reuse voltage-ranges property,
> > it is already implemented for mmc spi driver,
> > 
> > drivers/mmc/host/of_mmc_spi.c
> > Documentation/devicetree/bindings/mmc/mmc-spi-slot.txt
> > 
> > Thanks,
> > 
> > Anton
> > --
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