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

From: Simon Horman <horms@verge.net.au>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] ARM: shmobile: kzm9g dts: Use adxl345-specific compatible property
Date: Fri, 14 Aug 2015 04:54:16 +0000	[thread overview]
Message-ID: <20150814045414.GA7739@verge.net.au> (raw)
In-Reply-To: <10744920.2768uXkYtL@avalon>

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.