linux-kernel - Re: [PATCH v7 2/5] of: change overlay apply input data from unflattened to FDT

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Date:   Wed, 25 Apr 2018 07:38:02 +0200
From:   Jan Kiszka <jan.kiszka@....de>
To:     Alan Tull <atull@...nel.org>
Cc:     Frank Rowand <frowand.list@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Pantelis Antoniou <panto@...oniou-consulting.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Jailhouse <jailhouse-dev@...glegroups.com>
Subject: Re: [PATCH v7 2/5] of: change overlay apply input data from
 unflattened to FDT

On 2018-04-24 20:26, Alan Tull wrote:
> On Tue, Apr 24, 2018 at 11:08 AM, Alan Tull <atull@...nel.org> wrote:
>> On Tue, Apr 24, 2018 at 12:29 AM, Jan Kiszka <jan.kiszka@....de> wrote:
>>>
>>> We have drivers/fpga/of-fpga-region.c in-tree, and that does not seem to
>>> store any pointers to objects, rather consumes them in-place. And I
>>> would consider it fair to impose such a limitation on the notifier
>>> interface.
>>
>> The FPGA code was written assuming that overlays could be removed.
> 
> To be more specific, drivers/fpga/of-fpga-region.c currently saves a
> pointer to the overlay and uses it only during the pre-apply
> notification.

Even more exactly: You are saving a reference during pre-apply and
freeing that one again on the corresponding post-remove. That is what I
would have expected as normal usage of the notification API as well.

Jan