linux-kernel - Re: [PATCH] drm/bridge: fix RC

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Date:   Thu, 18 Jul 2019 18:17:09 +0300
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Ronald Tschalär <ronald@...ovation.ch>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Sean Paul <sean@...rly.run>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/bridge: fix RC_CORE dependency

On Thu, Jul 18, 2019 at 6:13 PM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Thu, Jul 18, 2019 at 4:56 PM Andrzej Hajda <a.hajda@...sung.com> wrote:
> > On 18.07.2019 16:21, Arnd Bergmann wrote:
> > > On Thu, Jul 18, 2019 at 4:16 PM Andrzej Hajda <a.hajda@...sung.com> wrote:
> > >> Hi Arnd,
> > >>
> > >> On 18.07.2019 15:42, Arnd Bergmann wrote:
> > >>> Using 'imply' causes a new problem, as it allows the case of
> > >>> CONFIG_INPUT=m with RC_CORE=y, which fails to link:
> > >>>
> > >>> drivers/media/rc/rc-main.o: In function `ir_do_keyup':
> > >>> rc-main.c:(.text+0x2b4): undefined reference to `input_event'
> > >>> drivers/media/rc/rc-main.o: In function `rc_repeat':
> > >>> rc-main.c:(.text+0x350): undefined reference to `input_event'
> > >>> drivers/media/rc/rc-main.o: In function `rc_allocate_device':
> > >>> rc-main.c:(.text+0x90c): undefined reference to `input_allocate_device'
> > >>>
> > >>> Add a 'depends on' that allows building both with and without
> > >>> CONFIG_RC_CORE, but disallows combinations that don't link.
> > >>>
> > >>> Fixes: 5023cf32210d ("drm/bridge: make remote control optional")
> > >>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> > >>
> > >> Proper solution has been already merged via input tree[1].
> > >>
> > >>
> > >> [1]:
> > >> https://lore.kernel.org/lkml/CAKdAkRTGXNbUsuKASNGLfwUwC7Asod9K5baYLPWPU7EX-42-yA@mail.gmail.com/
> > > At that link, I only see the patch that caused the regression, not
> > > the solution. Are you sure it's fixed?
> >
> >
> > Ups, you are right, I though you are fixing what this patch attempted to
> > fix :)
> >
> > Anyway, we want to avoid dependency on RC_CORE - this driver does not
> > require it, but with RC_CORE it has additional features.
>
> Right, that's what my patch does: if RC_CORE is disabled, you can
> still set DRM_SIL_SII8620=y, but if RC_CORE=m, DRM_SIL_SII8620
> can only be =m or =n.
>
> > Maybe "imply INPUT" would help?
>
> No, that would make it worse. Device drivers really have no business
> turning on other subsystems.
>

OK, in the meantime I will redo the branch by dropping the
sil-sii8620.c Kconfig changes and also drop all "imply" business from
applespi driver as they give us more trouble than they are worth. We
do not have "imply" for i801_smbus for Symaptics SMBUS mode and it
works fine. It it distro's task to configure the kernel properly.

Thanks.

-- 
Dmitry