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Date:   Wed, 15 Jun 2022 13:24:42 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Alex Deucher <alexdeucher@gmail.com>
Cc:     Randy Dunlap <rdunlap@infradead.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        Alex Deucher <alexander.deucher@amd.com>,
        Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
        Bhanuprakash Modem <bhanuprakash.modem@intel.com>
Subject: Re: linux-next: Tree for Jun 15
 (drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c)
Message-ID: <YqpACmvbwiEcUfta@dev-arch.thelio-3990X>
References: <20220615160116.528c324b@canb.auug.org.au>
 <d1a48a84-6d07-e8f7-5fd8-d24a7a1cf187@infradead.org>
 <CADnq5_N6gfaPfZJAX4+poWFFruxNdFKZqzXZXosj1A55e-O1mA@mail.gmail.com>
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On Wed, Jun 15, 2022 at 03:28:52PM -0400, Alex Deucher wrote:
> On Wed, Jun 15, 2022 at 3:01 PM Randy Dunlap <rdunlap@infradead.org> wrote:
> >
> >
> >
> > On 6/14/22 23:01, Stephen Rothwell wrote:
> > > Hi all,
> > >
> > > Changes since 20220614:
> > >
> >
> > on i386:
> > # CONFIG_DEBUG_FS is not set
> >
> >
> > ../drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c: In function ‘amdgpu_dm_crtc_late_register’:
> > ../drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:6599:2: error: implicit declaration of function ‘crtc_debugfs_init’; did you mean ‘amdgpu_debugfs_init’? [-Werror=implicit-function-declaration]
> >   crtc_debugfs_init(crtc);
> >   ^~~~~~~~~~~~~~~~~
> >   amdgpu_debugfs_init
> >
> >
> > Full randconfig file is attached.
> 
> I tried building with your config and I can't repro this.  As Harry
> noted, that function and the whole secure display feature depend on
> debugfs.  It should never be built without CONFIG_DEBUG_FS.  See
> drivers/gpu/drm/amd/display/Kconfig:
> 
> > config DRM_AMD_SECURE_DISPLAY
> >         bool "Enable secure display support"
> >         default n
> >         depends on DEBUG_FS
> >         depends on DRM_AMD_DC_DCN
> >         help
> >             Choose this option if you want to
> >             support secure display
> >
> >             This option enables the calculation
> >             of crc of specific region via debugfs.
> >             Cooperate with specific DMCU FW.
> 
> amdgpu_dm_crtc_late_register is guarded by
> CONIG_DRM_AMD_SECURE_DISPLAY.  It's not clear to me how we could hit
> this.

I think the problem is that you are not looking at the right tree.

The kernel test robot reported [1] [2] this error is caused by commit
4cd79f614b50 ("drm/amd/display: Move connector debugfs to drm"), which
is in the drm-misc tree on the drm-misc-next branch. That change removes
the #ifdef around amdgpu_dm_crtc_late_register(), meaning that
crtc_debugfs_init() can be called without CONFIG_DRM_AMD_SECURE_DISPLAY
and CONFIG_DEBUG_FS.

  $ git show -s --format='%h ("%s")'
  abf0ba5a34ea ("drm/bridge: it6505: Add missing CRYPTO_HASH dependency")

  $ make -skj"$(nproc)" ARCH=x86_64 mrproper defconfig

  $ scripts/config -d BLK_DEV_IO_TRACE -d DEBUG_FS -e DRM_AMDGPU

  $ make -skj"$(nproc)" ARCH=x86_64 olddefconfig drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.o
  drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c: In function ‘amdgpu_dm_crtc_late_register’:
  drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:6622:9: error: implicit declaration of function ‘crtc_debugfs_init’; did you mean ‘amdgpu_debugfs_init’? [-Werror=implicit-function-declaration]
   6622 |         crtc_debugfs_init(crtc);
        |         ^~~~~~~~~~~~~~~~~
        |         amdgpu_debugfs_init
  cc1: all warnings being treated as errors

Contrast that with the current top of your tree:

  $ git show -s --format='%h ("%s")'
  c435f61d0eb3 ("drm/amd/display: Drop unnecessary guard from DC resource")

  $ make -skj"$(nproc)" ARCH=x86_64 mrproper defconfig

  $ scripts/config -d BLK_DEV_IO_TRACE -d DEBUG_FS -e DRM_AMDGPU

  $ make -skj"$(nproc)" ARCH=x86_64 olddefconfig drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.o

  $ echo $?
  0

Randy's patch [3] seems like it should resolve the issue just fine but
it needs to be applied to drm-misc-next, not the amdgpu tree.

[1]: https://lore.kernel.org/202205241843.8EWKesIA-lkp@intel.com/
[2]: https://lore.kernel.org/202205240207.KmDLuSrC-lkp@intel.com/
[3]: https://lore.kernel.org/20220614155726.26211-1-rdunlap@infradead.org/

Cheers,
Nathan