Re: linux-next: Tree for Jun 15 (drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c)

[Nathan Chancellor <nathan@kernel.org>]

On Wed, Jun 15, 2022 at 04:45:16PM -0400, Alex Deucher wrote:
> On Wed, Jun 15, 2022 at 4:24 PM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > 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.
> 
> Thanks for tracking this down.  I think something like the attached
> patch is cleaner since the whole thing is only valid for debugfs.

Makes sense! I tested the below patch with and without DEBUG_FS and saw
no errors.

> From b0bcacd86344998e0ca757f89c6c4cd3b6298999 Mon Sep 17 00:00:00 2001
> From: Alex Deucher <alexander.deucher@amd.com>
> Date: Wed, 15 Jun 2022 16:40:39 -0400
> Subject: [PATCH] drm/amdgpu/display: fix build when CONFIG_DEBUG_FS is not set
> 
> amdgpu_dm_crtc_late_register is only used when CONFIG_DEBUG_FS
> so make it dependent on that.
> 
> Fixes: 4cd79f614b50 ("drm/amd/display: Move connector debugfs to drm")
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Reported-by: Nathan Chancellor <nathan@kernel.org>

Tested-by: Nathan Chancellor <nathan@kernel.org> # build

> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index c9004f7e700d..33cd7a3d4ecb 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -6594,12 +6594,14 @@ dm_crtc_duplicate_state(struct drm_crtc *crtc)
>  	return &state->base;
>  }
>  
> +#ifdef CONFIG_DEBUG_FS
>  static int amdgpu_dm_crtc_late_register(struct drm_crtc *crtc)
>  {
>  	crtc_debugfs_init(crtc);
>  
>  	return 0;
>  }
> +#endif
>  
>  static inline int dm_set_vupdate_irq(struct drm_crtc *crtc, bool enable)
>  {
> @@ -6693,7 +6695,9 @@ static const struct drm_crtc_funcs amdgpu_dm_crtc_funcs = {
>  	.enable_vblank = dm_enable_vblank,
>  	.disable_vblank = dm_disable_vblank,
>  	.get_vblank_timestamp = drm_crtc_vblank_helper_get_vblank_timestamp,
> +#if defined(CONFIG_DEBUG_FS)
>  	.late_register = amdgpu_dm_crtc_late_register,
> +#endif
>  };
>  
>  static enum drm_connector_status
> -- 
> 2.35.3
>