linux-kernel - Re: [PATCH 3/3] drm/pl111: depend on CONFIG_VEXPRESS

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Message-ID: <CAKMK7uG8ZiToP2vFsr7TuhntWWh0yiaHkwU5mx5EaESoy+tTHQ@mail.gmail.com>
Date:   Thu, 3 Jun 2021 23:41:01 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Kees Cook <keescook@...omium.org>
Cc:     Rob Herring <robh@...nel.org>, Dave Airlie <airlied@...hat.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Arnd Bergmann <arnd@...nel.org>,
        kernel test robot <lkp@...el.com>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Emma Anholt <emma@...olt.net>, Rob Clark <robdclark@...il.com>,
        Sean Paul <sean@...rly.run>,
        Sharat Masetty <smasetty@...eaurora.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>
Subject: Re: [PATCH 3/3] drm/pl111: depend on CONFIG_VEXPRESS_CONFIG

On Thu, Jun 3, 2021 at 11:29 PM Kees Cook <keescook@...omium.org> wrote:
>
> On Thu, Jun 03, 2021 at 02:19:52PM -0700, Kees Cook wrote:
> > On Thu, Jun 03, 2021 at 09:19:42PM +0200, Daniel Vetter wrote:
> > > On Thu, Jun 3, 2021 at 8:43 PM Rob Herring <robh@...nel.org> wrote:
> > > >
> > > > On Wed, Jun 2, 2021 at 4:53 PM Kees Cook <keescook@...omium.org> wrote:
> > > > >
> > > > > Avoid randconfig build failures by requiring VEXPRESS_CONFIG:
> > > > >
> > > > > aarch64-linux-gnu-ld: drivers/gpu/drm/pl111/pl111_versatile.o: in function `pl111_vexpress_clcd_init':
> > > > > pl111_versatile.c:(.text+0x220): undefined reference to `devm_regmap_init_vexpress_config'
> > > >
> > > > pl111_vexpress_clcd_init() starts with:
> > > >
> > > > if (!IS_ENABLED(CONFIG_VEXPRESS_CONFIG))
> > > >                 return -ENODEV;
> > > >
> > > > Isn't that supposed to be enough to avoid an undefined reference?
> >
> > Ah! I missed that when reading the code. I see the problem now. It's
> > because of:
> >
> > CONFIG_VEXPRESS_CONFIG=m
> > CONFIG_DRM_PL111=y
> >
> > I think the right fix is:
> >
> > diff --git a/drivers/gpu/drm/pl111/Kconfig b/drivers/gpu/drm/pl111/Kconfig
> > index 80f6748055e3..662fc38f92ba 100644
> > --- a/drivers/gpu/drm/pl111/Kconfig
> > +++ b/drivers/gpu/drm/pl111/Kconfig
> > @@ -3,6 +3,7 @@ config DRM_PL111
> >       tristate "DRM Support for PL111 CLCD Controller"
> >       depends on DRM
> >       depends on ARM || ARM64 || COMPILE_TEST
> > +     depends on VEXPRESS_CONFIG=y || VEXPRESS_CONFIG=DRM
>
> Oops, no, I had this backwairds:
>
>         depends on !VEXPRESS_CONFIG || VEXPRESS_CONFIG=DRM

Can you pls throw this into an incremental patch on top of
drm-misc-next? It's a non-rebasing tree and all that (linux-next
should have it next day too I guess).

Thanks, Daniel

> _that_ lets me build with:
>
> # CONFIG_VEXPRESS_CONFIG is not set
> CONFIG_DRM_PL111=y
>
> CONFIG_VEXPRESS_CONFIG=y
> CONFIG_DRM_PL111=y
>
> CONFIG_VEXPRESS_CONFIG=m
> CONFIG_DRM_PL111=m
>
> CONFIG_VEXPRESS_CONFIG=y
> CONFIG_DRM_PL111=m
>
> and disallows:
>
> CONFIG_VEXPRESS_CONFIG=m
> CONFIG_DRM_PL111=y
>
> (this will force CONFIG_DRM_PL111=m)
>
> -Kees
>
> >       depends on COMMON_CLK
> >       select DRM_KMS_HELPER
> >       select DRM_KMS_CMA_HELPER
> >
> > I will go check the defconfigs Rob mentioned...
> >
> > > > Making the whole file depend on VEXPRESS_CONFIG is not right either.
> > > > Not all platforms need it.
> > >
> > > It needs a compile-time status inline then for the functions we're
> > > using in pl111.
> >
> > FYI, this is the config I was working from, which was throwing link errors:
> > https://lore.kernel.org/lkml/202105300926.fX0MYySp-lkp@intel.com/
> >
> > > -Daniel
> > >
> > > >
> > > > >
> > > > > Fixes: 826fc86b5903 ("drm: pl111: Move VExpress setup into versatile init")
> > > > > Signed-off-by: Kees Cook <keescook@...omium.org>
> > > > > ---
> > > > >  drivers/gpu/drm/pl111/Kconfig | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/pl111/Kconfig b/drivers/gpu/drm/pl111/Kconfig
> > > > > index 80f6748055e3..c5210a5bef1b 100644
> > > > > --- a/drivers/gpu/drm/pl111/Kconfig
> > > > > +++ b/drivers/gpu/drm/pl111/Kconfig
> > > > > @@ -2,7 +2,7 @@
> > > > >  config DRM_PL111
> > > > >         tristate "DRM Support for PL111 CLCD Controller"
> > > > >         depends on DRM
> > > > > -       depends on ARM || ARM64 || COMPILE_TEST
> > > > > +       depends on VEXPRESS_CONFIG
> > > > >         depends on COMMON_CLK
> > > > >         select DRM_KMS_HELPER
> > > > >         select DRM_KMS_CMA_HELPER
> > > > > --
> > > > > 2.25.1
> > > > >
> > >
> > >
> > >
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > http://blog.ffwll.ch
> >
> > --
> > Kees Cook
>
> --
> Kees Cook



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch