Re: [PATCH v2 0/7] Change snvs rtc and poweroff to use syscon add pwrkey driver

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Wed, May 20, 2015 at 07:30:50PM +0100, Russell King - ARM Linux wrote:
> On Wed, May 20, 2015 at 07:25:41PM +0100, Russell King - ARM Linux wrote:
> > On Wed, May 20, 2015 at 09:58:51AM +0800, Shawn Guo wrote:
> > > On Wed, May 20, 2015 at 01:04:35AM +0800, Frank.Li@freescale.com wrote:
> > > > Frank Li (6):
> > > >   arm: imx: power-off: change to syscon to access register
> > > >   rtc: arm: imx: snvs: change use syscon to access register
> > > >   Document: dt: fsl: snvs: change support syscon
> > > >   arm: dts: imx: update snvs to use syscon access register
> > > >   document: devicetree: input: imx: i.mx snvs power device tree bindings
> > > >   arm: dts: imx6sx: enable snvs power key
> > > 
> > > So, the series will break existing DTBs for RTC and poweroff, right?
> > > If this is unavoidable, should we at least have some warning messages
> > > telling users about his breakage?
> > 
> > What's the justification for breaking existing DTBs?  Really, this is
> > something we should strive to avoid, _and_ actually avoid by providing
> > backwards compatibility.
> 
> Looking at the RTC code, it would be pretty trivial to do.
> 
> Rather than passing around struct regmap, pass around the private data
> structure.
> 
> Rename the regmap_* function calls to be private accessors.  Implement
> a set of new accessors - if the private data has the regmap, use the
> regmap API.  Otherwise, use the old method, and print a warning that an
> old DT is being used.

Or maybe have drivers create regmap themselves if they see old DTS and
not bother with the 2 sets of accessors?

Thanks.

-- 
Dmitry