From: Daniel Vetter <daniel@ffwll.ch>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Jernej Skrabec <jernej.skrabec@siol.net>,
Leon Romanovsky <leon@kernel.org>,
Nicolas Pitre <nico@fluxnic.net>, David Airlie <airlied@linux.ie>,
Networking <netdev@vger.kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Neil Armstrong <narmstrong@baylibre.com>,
Saeed Mahameed <saeedm@mellanox.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
Andrzej Hajda <a.hajda@samsung.com>,
Jonas Karlman <jonas@kwiboo.se>,
Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
"David S. Miller" <davem@davemloft.net>,
linux-rdma <linux-rdma@vger.kernel.org>
Subject: Re: [RFC 5/6] drm/rcar-du: fix selection of CMM driver
Date: Thu, 16 Apr 2020 08:51:14 +0200 [thread overview]
Message-ID: <CAKMK7uEoZ1jC8c25tPVX20kcdC1=+TpUUNyf+-c=sg5iK2cTZA@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a1rDZO4cuL6VAXgu9sOiedcHqOSL7ELhpvULz+YYRaGbA@mail.gmail.com>
On Wed, Apr 15, 2020 at 11:22 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Wed, Apr 15, 2020 at 11:12 PM Laurent Pinchart
> <laurent.pinchart@ideasonboard.com> wrote:
> > On Wed, Apr 15, 2020 at 09:07:14PM +0200, Arnd Bergmann wrote:
> > > On Wed, Apr 15, 2020 at 5:18 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > > > On Wed, Apr 15, 2020 at 4:13 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > > > On Wed, Apr 15, 2020 at 3:47 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > > > > > On Tue, Apr 14, 2020 at 10:52 PM Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote:
> > > > > > > Doesn't "imply" mean it gets selected by default but can be manually
> > > > > > > disabled ?
> > > > > >
> > > > > > That may be what it means now (I still don't understand how it's defined
> > > > > > as of v5.7-rc1), but traditionally it was more like a 'select if all
> > > > > > dependencies are met'.
> > > > >
> > > > > That's still what it is supposed to mean right now ;-)
> > > > > Except that now it should correctly handle the modular case, too.
> > > >
> > > > Then there is a bug. If I run 'make menuconfig' now on a mainline kernel
> > > > and enable CONFIG_DRM_RCAR_DU, I can set
> > > > DRM_RCAR_CMM and DRM_RCAR_LVDS to 'y', 'n' or 'm' regardless
> > > > of whether CONFIG_DRM_RCAR_DU is 'm' or 'y'. The 'implies'
> > > > statement seems to be ignored entirely, except as reverse 'default'
> > > > setting.
> > >
> > > Here is another version that should do what we want and is only
> > > half-ugly. I can send that as a proper patch if it passes my testing
> > > and nobody hates it too much.
> >
> > This may be a stupid question, but doesn't this really call for fixing
> > Kconfig ? This seems to be such a common pattern that requiring
> > constructs similar to the ones below will be a never-ending chase of
> > offenders.
>
> Maybe, I suppose the hardest part here would be to come up with
> an appropriate name for the keyword ;-)
>
> Any suggestions?
>
> This specific issue is fairly rare though, in most cases the dependencies
> are in the right order so a Kconfig symbol 'depends on' a second one
> when the corresponding loadable module uses symbols from that second
> module. The problem here is that the two are mixed up.
>
> The much more common problem is the one where one needs to
> wrong
>
> config FOO
> depends on BAR || !BAR
>
> To ensure the dependency is either met or BAR is disabled, but
> not FOO=y with BAR=m. If you have any suggestions for a keyword
> for that thing, we can clean up hundreds of such instances.
Some ideas:
config FOO
can use BAR
maybe BAR
optional BAR
We should probably double-check that this is only ever used for when
both FOO and BAR are tri-state, since without that it doesn't make
much sense.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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next prev parent reply other threads:[~2020-04-16 6:51 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-08 20:27 [RFC 0/6] Regressions for "imply" behavior change Arnd Bergmann
2020-04-08 20:27 ` [RFC 1/6] thunder: select PTP driver if possible Arnd Bergmann
2020-04-08 20:27 ` [RFC 2/6] net/mlx5e: fix VXLAN dependency Arnd Bergmann
2020-04-08 20:27 ` [RFC 3/6] LiquidIO VF: add dependency for PTP_1588_CLOCK Arnd Bergmann
2020-04-08 20:27 ` [RFC 4/6] drm/bridge/sii8620: fix extcon dependency Arnd Bergmann
2020-04-10 6:56 ` Andrzej Hajda
2020-04-14 15:04 ` Arnd Bergmann
2020-04-14 15:37 ` Daniel Vetter
2020-04-15 6:58 ` Jani Nikula
2020-04-08 20:27 ` [RFC 5/6] drm/rcar-du: fix selection of CMM driver Arnd Bergmann
2020-04-14 20:17 ` Laurent Pinchart
2020-04-14 20:38 ` Arnd Bergmann
2020-04-14 20:51 ` Laurent Pinchart
2020-04-14 21:10 ` Arnd Bergmann
2020-04-15 14:13 ` Geert Uytterhoeven
2020-04-15 15:18 ` Arnd Bergmann
2020-04-15 19:07 ` Arnd Bergmann
2020-04-15 21:12 ` Laurent Pinchart
2020-04-15 21:22 ` Arnd Bergmann
2020-04-16 6:51 ` Daniel Vetter [this message]
2020-04-16 15:17 ` Laurent Pinchart
2020-04-08 20:27 ` [RFC 6/6] drm/rcar-du: fix lvds dependency Arnd Bergmann
2020-04-08 20:38 ` [RFC 0/6] Regressions for "imply" behavior change Nicolas Pitre
2020-04-08 20:46 ` Saeed Mahameed
2020-04-08 20:49 ` Arnd Bergmann
2020-04-08 21:17 ` Nicolas Pitre
2020-04-08 22:42 ` Jason Gunthorpe
2020-04-09 8:41 ` Jani Nikula
2020-04-10 2:40 ` Saeed Mahameed
2020-04-10 7:26 ` Geert Uytterhoeven
2020-04-10 17:13 ` Jason Gunthorpe
2020-04-10 19:04 ` Saeed Mahameed
2020-04-14 13:29 ` Jason Gunthorpe
2020-04-14 14:27 ` Arnd Bergmann
2020-04-14 15:23 ` Jason Gunthorpe
2020-04-14 15:25 ` Arnd Bergmann
2020-04-14 17:49 ` Saeed Mahameed
2020-04-14 18:47 ` Arnd Bergmann
2020-04-16 3:25 ` Saeed Mahameed
2020-04-16 7:20 ` Arnd Bergmann
2020-04-16 10:17 ` Jani Nikula
2020-04-16 12:38 ` Arnd Bergmann
2020-04-16 14:52 ` Jason Gunthorpe
2020-04-16 15:58 ` Arnd Bergmann
2020-04-16 18:05 ` Jason Gunthorpe
2020-04-16 18:38 ` Saeed Mahameed
2020-04-16 15:12 ` Nicolas Pitre
2020-04-16 18:21 ` Jason Gunthorpe
2020-04-16 19:56 ` Andrzej Hajda
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