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From:   Arnd Bergmann <arnd@kernel.org>
Date:   Thu, 5 Aug 2021 08:50:41 +0200
Message-ID: <CAK8P3a1rAr0BH6cNLkhES+81x2hWW31RTLZkHLDJYK-r8+x6Gg@mail.gmail.com>
Subject: Re: [PATCH] depend on BACKLIGHT_CLASS_DEVICE for more devices
To:     Karol Herbst <kherbst@redhat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Lyude Paul <lyude@redhat.com>, Ben Skeggs <bskeggs@redhat.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        ML nouveau <nouveau@lists.freedesktop.org>,
        dri-devel <dri-devel@lists.freedesktop.org>
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On Thu, Aug 5, 2021 at 12:01 AM Karol Herbst <kherbst@redhat.com> wrote:
>
> On Wed, Aug 4, 2021 at 11:10 PM Arnd Bergmann <arnd@kernel.org> wrote:
> >
> > On Wed, Aug 4, 2021 at 8:59 PM Karol Herbst <kherbst@redhat.com> wrote:
> > > On Wed, Aug 4, 2021 at 4:43 PM Karol Herbst <kherbst@redhat.com> wrote:
> > > > On Wed, Aug 4, 2021 at 4:19 PM Arnd Bergmann <arnd@kernel.org> wrote:
> > > > > On Wed, Aug 4, 2021 at 4:10 PM Karol Herbst <kherbst@redhat.com> wrote:
> > > > > >
> > > > > > playing around a little bit with this, I think the original "select
> > > > > > BACKLIGHT_CLASS_DEVICE" is fine. Atm we kind of have this weird mix of
> > > > > > drivers selecting and others depending on it. We could of course convert
> > > > > > everything over to depend, and break those cycling dependency issues with
> > > > > > this.
> > > > > >
> > > > > > Anyway this change on top of my initial patch is enough to make Kconfig
> > > > > > happy and has the advantage of not having to mess with the deps of nouveau
> > > > > > too much.
> > > > >
> > > > > Looks good to me. We'd probably want to make the BACKLIGHT_CLASS_DEVICE
> > > > > option itself 'default FB || DRM' though, to ensure that defconfigs
> > > > > keep working.
> > > > >
> > > >
> > > > okay cool. Will send out a proper updated patch series soonish.
> > > >
> > >
> > > mhh, actually that breaks drivers selecting FB_BACKLIGHT as now
> > > BACKLIGHT_CLASS_DEVICE might be disabled :(
> >
> > Are you sure? It should already be the case that any driver that selects
> > FB_BACKLIGHT either 'depends on BACKLIGHT_CLASS_DEVICE'
> > or 'select BACKLIGHT_CLASS_DEVICE'.
> >
> none of the fb drivers seem to do that.

Ah, right, I see now that my randconfig series has a couple of patches
applied that deal with other random failures, including this one:

https://patchwork.kernel.org/project/linux-fbdev/patch/20200417155553.675905-8-arnd@arndb.de/

Part of the series went in (through different ways) now, but this one
never did.

      Arnd