[PATCH 1/4] mfd: mc13xxx: Honor designed SPI mode

[s.hauer@pengutronix.de (Sascha Hauer)]

On Wed, Mar 05, 2014 at 12:51:05AM +0400, Alexander Shiyan wrote:
> ???????,  4 ????? 2014, 21:13 +01:00 ?? Sascha Hauer <s.hauer@pengutronix.de>:
> > On Mon, Mar 03, 2014 at 01:51:05PM +0400, Alexander Shiyan wrote:
> > > ???????????,  3 ????? 2014, 10:41 +01:00 ?? Sascha Hauer <s.hauer@pengutronix.de>:
> > > > On Sun, Mar 02, 2014 at 11:44:32AM +0400, Alexander Shiyan wrote:
> > > > > Instead of using hard coded SPI mode, use mode described in
> > > > > devicetree or defined for the board.
> > > > > Additionally, patch updates all users of this PMIC to use
> > > > > correct SPI mode.
> > > > 
> > > > What's the reason for this change? Without it the driver just does the
> > > > correct thing, this only adds a chance for boards do get it wrong. This
> > > > for example happens with the i.MX27 phyCORE in this patch, see
> > > > happens with arch/arm/boot/dts/imx27-phytec-phycore-som.dts whih doesn't
> > > > have the spi-cs-high property.
> > > 
> > > How specify proper functionality if chipselect connected through inverter?
> > 
> > Is there such a hardware around?
> 
> AFAIK no, but it is a protection for the future. Since this driver handle several PMICs,
> we must anticipate the addition of new types of ICs and the emergence of new
> devices using these PMICs, which could use external logic for chipselect.
> Instead use tricks, use proper definitions (or DT description), from my point of view,
> better.

In that case rather than breaking devicetree compatibility we really
should leave this problem to someone who actually has this problem. He
could introduce an explicit spi-cs-low property to overwrite the driver
preference.

Sascha

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