From: Arnd Bergmann <arnd@arndb.de>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Jernej Skrabec <jernej.skrabec@siol.net>,
Leon Romanovsky <leon@kernel.org>,
Neil Armstrong <narmstrong@baylibre.com>,
David Airlie <airlied@linux.ie>,
Networking <netdev@vger.kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Jonas Karlman <jonas@kwiboo.se>,
Saeed Mahameed <saeedm@mellanox.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Nicolas Pitre <nico@fluxnic.net>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
Andrzej Hajda <a.hajda@samsung.com>,
Kieran Bingham <kieran.bingham+renesas@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: Tue, 14 Apr 2020 23:10:08 +0200 [thread overview]
Message-ID: <CAK8P3a1PZbwdvdH_Gi9UQVUz2+_a8QDxKuWLqPtjhK1stxzMBQ@mail.gmail.com> (raw)
In-Reply-To: <20200414205158.GM19819@pendragon.ideasonboard.com>
On Tue, Apr 14, 2020 at 10:52 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Arnd,
>
> On Tue, Apr 14, 2020 at 10:38:27PM +0200, Arnd Bergmann wrote:
> > On Tue, Apr 14, 2020 at 10:17 PM Laurent Pinchart wrote:
> > > On Wed, Apr 08, 2020 at 10:27:10PM +0200, Arnd Bergmann wrote:
> > > > The 'imply' statement does not seem to have an effect, as it's
> > > > still possible to turn the CMM code into a loadable module
> > > > in a randconfig build, leading to a link error:
> > > >
> > > > arm-linux-gnueabi-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_crtc_atomic_enable':
> > > > rcar_du_crtc.c:(.text+0xad4): undefined reference to `rcar_lvds_clk_enable'
> > > > arm-linux-gnueabi-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_crtc_atomic_disable':
> > > > rcar_du_crtc.c:(.text+0xd7c): undefined reference to `rcar_lvds_clk_disable'
> > > > arm-linux-gnueabi-ld: drivers/gpu/drm/rcar-du/rcar_du_drv.o: in function `rcar_du_init':
> > > > rcar_du_drv.c:(.init.text+0x4): undefined reference to `rcar_du_of_init'
> > > > arm-linux-gnueabi-ld: drivers/gpu/drm/rcar-du/rcar_du_encoder.o: in function `rcar_du_encoder_init':
> > > >
> > > > Remove the 'imply', and instead use a silent symbol that defaults
> > > > to the correct setting.
> > >
> > > This will result in the CMM always being selected when DU is, increasing
> > > the kernel size even for devices that don't need it. I believe we need a
> > > better construct in Kconfig to fix this.
> >
> > I had expected this to have the same meaning that we had before the
> > Kconfig change: whenever the dependencies are available, turn it on,
> > otherwise leave it disabled.
> >
> > Can you describe what behavior you actually want instead?
>
> 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'.
> > > > --- a/drivers/gpu/drm/rcar-du/Kconfig
> > > > +++ b/drivers/gpu/drm/rcar-du/Kconfig
> > > > @@ -4,7 +4,6 @@ config DRM_RCAR_DU
> > > > depends on DRM && OF
> > > > depends on ARM || ARM64
> > > > depends on ARCH_RENESAS || COMPILE_TEST
> > > > - imply DRM_RCAR_CMM
> > > > imply DRM_RCAR_LVDS
> > > > select DRM_KMS_HELPER
> > > > select DRM_KMS_CMA_HELPER
> > > > @@ -15,9 +14,8 @@ config DRM_RCAR_DU
> > > > If M is selected the module will be called rcar-du-drm.
> > > >
> > > > config DRM_RCAR_CMM
> > > > - tristate "R-Car DU Color Management Module (CMM) Support"
> > > > + def_tristate DRM_RCAR_DU
> > > > depends on DRM && OF
> > > > - depends on DRM_RCAR_DU
> > > > help
> >
> > It would be easy enough to make this a visible 'bool' symbol and
> > build it into the rcu-du-drm.ko module itself. Would that help you?
>
> That could indeed simplify a few things. I wonder if it could introduce
> a few small issues though (but likely nothing we can't fix). The two
> that come to mind are the fact that the module would have two
> MODULE_DESCRIPTION and MODULE_LICENSE entries (I have no idea if that
> could cause breakages), and that it could make module unloading more
> difficult as the CMM being used by the DU would increase the refcount on
> the module. I think the latter could be worked around by manually
> unbinding the DU device through sysfs before unloading the module (and I
> can't say for sure that unloading the DU module is not broken today
> *innocent and naive look* :-)).
In that case, a Makefile trick could also work, doing
ifdef CONFIG_DRM_RCAR_CMM
obj-$(CONFIG_DRM_RCAR_DU) += rcar-cmm.o
endif
Thereby making the cmm module have the same state (y or m) as
the du module whenever the option is enabled.
Arnd
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next prev parent reply other threads:[~2020-04-14 21:10 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 [this message]
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
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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