Re: [PATCH v2] ARM: shmobile: kzm9g dts: Use adxl345-specific compatible property

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Simon,

On Friday 14 August 2015 13:54:16 Simon Horman wrote:
> On Fri, Aug 14, 2015 at 12:31:09AM +0300, Laurent Pinchart wrote:
> > On Thursday 13 August 2015 11:26:32 Geert Uytterhoeven wrote:
> >> On Thu, Aug 13, 2015 at 2:05 AM, Simon Horman <horms@verge.net.au> wrote:
> >>> On Wed, Jul 08, 2015 at 09:51:49AM +0900, Simon Horman wrote:
> >>>> On Tue, Jul 07, 2015 at 09:56:29AM +0300, Laurent Pinchart wrote:
> >>>>> On Tuesday 07 July 2015 09:26:21 Simon Horman wrote:
> >>>>>> On Mon, Jul 06, 2015 at 04:29:33PM +0300, Laurent Pinchart wrote:
> >>>>>>> On Monday 06 July 2015 12:55:32 Geert Uytterhoeven wrote:
> >>>>>>>> Replace the deprecated generic "adi,adxl34x" compatible value by
> >>>>>>>> the adxl345-specific "adi,adxl345" value, cfr. commit
> >>>>>>>> e465bf6fc55d5ce2 ("DT:
> >>>>>>>> i2c: Deprecate adi,adxl34x compatible string").
> >>>>>>>> 
> >>>>>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >>>>>>> 
> >>>>>>> Acked-by: Laurent Pinchart
> >>>>>>> <laurent.pinchart+renesas@ideasonboard.com>
> >>>>>>> 
> >>>>>>>> ---
> >>>>>>>> Depends on commit 3a38958d2477b718 ("Input: adxl34x - add OF
> >>>>>>>> match support"), which is in v4.2-rc1.
> >>>>>>>> 
> >>>>>>>> This is v2 of "ARM: shmobile: kzm9g dts: Add adxl345-specific
> >>>>>>>> compatible property".
> >>>>>> 
> >>>>>> It appears to me that this will cause a regression when booting old
> >>>>>> kernels with new dts blobs. For that reason think we should
> >>>>>> consider v1 of this change coupled with a schedule to remove use of
> >>>>>> the deprecated compat string.
> >>>>> 
> >>>>> That's the forward compatibility that Geert mentioned, is that
> >>>>> really an issue, especially on this board ?
> >>>> 
> >>>> I think it would be best to provide backwards compatibility unless
> >>>> there is a compelling reason not to.
> >>> 
> >>> I would like to revisit this discussion with a view to getting some
> >>> version of this patch queued up (yes I know I pushed back on it
> >>> earlier in this thread).
> >> 
> >> I'm fine with applying v1.
> > 
> > And I'm quite unsurprisingly not, as I've asked for a v2.
> > 
> > The "adi,adxl34x" compatible string is deprecated. That means we still
> > support it in the driver for device trees that haven't been updated, but
> > it shouldn't be used forward by new device trees. That's why the device
> > tree sources contained in the kernel shouldn't use it, especially given
> > that they often serve as references for device trees shipped out of tree.
> 
> Thanks, I see your point now. I have queued up v2.

Thank you :-)

-- 
Regards,

Laurent Pinchart