Re: [PATCH 02/40] drm/amd/display: Add SubVP required code

[Nathan Chancellor <nathan@kernel.org>]

On Thu, Jun 30, 2022 at 03:12:44PM -0400, Rodrigo Siqueira wrote:
> From: Alvin Lee <Alvin.Lee2@amd.com>
> 
> This commit enables the SubVP feature. To achieve that, we need to:
> 
> - Don't force p-state disallow on SubVP (can't block dummy p-state)
> - Send calculated watermark to DMCUB for SubVP
> - Adjust CAB mode message to PMFW
> - Add a proper locking sequence for SubVP
> - Various fixes to SubVP static analysis and determining SubVP config
> - Currently SubVP not supported with pipe split so merge all pipes
>   before setting up SubVp
> 
> Reviewed-by: Jun Lei <Jun.Lei@amd.com>
> Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> Acked-by: Alan Liu <HaoPing.Liu@amd.com>
> Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>

This patch is now in linux-next as commit 85f4bc0c333c
("drm/amd/display: Add SubVP required code"), where it causes build
failures when building for arm64 with both Clang and GCC (see bisect log
below).

Clang shows errors during modpost:

ERROR: modpost: "__floatunsidf" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "__divdf3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "fma" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "__adddf3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "__fixdfsi" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "__muldf3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "__floatsidf" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "__fixunsdfsi" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!

GCC shows errors along the lines of:

In function 'populate_subvp_cmd_pipe_info',
    inlined from 'dc_dmub_setup_subvp_dmub_command' at /home/nathan/cbl/src/linux-next/drivers/gpu/drm/amd/amdgpu/../display/dc/dc_dmub_srv.c:675:5:
/home/nathan/cbl/src/linux-next/drivers/gpu/drm/amd/amdgpu/../display/dc/dc_dmub_srv.c:603:91: error: '-mgeneral-regs-only' is incompatible with the use of floating-point types
  603 |                         (((double)dc->caps.subvp_prefetch_end_to_mall_start_us / 1000000) *
      |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
  604 |                         (phantom_timing->pix_clk_100hz * 100) + phantom_timing->h_total - 1) /
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/nathan/cbl/src/linux-next/drivers/gpu/drm/amd/amdgpu/../display/dc/dc_dmub_srv.c:604:63: error: '-mgeneral-regs-only' is incompatible with the use of floating-point types
  603 |                         (((double)dc->caps.subvp_prefetch_end_to_mall_start_us / 1000000) *
      |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  604 |                         (phantom_timing->pix_clk_100hz * 100) + phantom_timing->h_total - 1) /
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/home/nathan/cbl/src/linux-next/drivers/gpu/drm/amd/amdgpu/../display/dc/dc_dmub_srv.c:602:72: error: '-mgeneral-regs-only' is incompatible with the use of floating-point types
  602 |         pipe_data->pipe_config.subvp_data.prefetch_to_mall_start_lines =
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
  603 |                         (((double)dc->caps.subvp_prefetch_end_to_mall_start_us / 1000000) *
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  604 |                         (phantom_timing->pix_clk_100hz * 100) + phantom_timing->h_total - 1) /
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  605 |                         (double)phantom_timing->h_total;
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I initially reproduced this with Fedora's configuration [1] but it
appears that allmodconfig should show it as well. Our CI also shows
problems for ARCH=riscv allmodconfig [2].

I am happy to test patches as necessary.

[1]: https://src.fedoraproject.org/rpms/kernel/raw/rawhide/f/kernel-aarch64-fedora.config
[2]: https://builds.tuxbuild.com/2BZS5HPSuDdoMFw6mxjG2ZmT441/build.log

Cheers,
Nathan

# bad: [088b9c375534d905a4d337c78db3b3bfbb52c4a0] Add linux-next specific files for 20220706
# good: [e35e5b6f695d241ffb1d223207da58a1fbcdff4b] Merge tag 'xsa-5.19-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
git bisect start '088b9c375534d905a4d337c78db3b3bfbb52c4a0' 'e35e5b6f695d241ffb1d223207da58a1fbcdff4b'
# good: [1a4255ede07a967e57115b54da5bd4b571d22a8c] Merge branch 'for-linux-next' of git://anongit.freedesktop.org/drm/drm-misc
git bisect good 1a4255ede07a967e57115b54da5bd4b571d22a8c
# bad: [756b44529e2ab179e4dd6f6358b5c351e1bbe5d3] Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
git bisect bad 756b44529e2ab179e4dd6f6358b5c351e1bbe5d3
# bad: [f26873a2fc786251765db3e0ced8e1424b862059] next-20220705/sound-asoc
git bisect bad f26873a2fc786251765db3e0ced8e1424b862059
# good: [fc34ece41f7183d522d15dc4189d8df6e8e23737] ASoC: Refactor non_legacy_dai_naming flag
git bisect good fc34ece41f7183d522d15dc4189d8df6e8e23737
# good: [3d313f09f31490cec9d5251b59adeb6542c944cc] drm/fourcc: fix integer type usage in uapi header
git bisect good 3d313f09f31490cec9d5251b59adeb6542c944cc
# bad: [a41afb357f09cde0714db9d590458c7bb6d90ca2] Merge branch 'for-linux-next' of git://anongit.freedesktop.org/drm-intel
git bisect bad a41afb357f09cde0714db9d590458c7bb6d90ca2
# bad: [88ef4c5bb36bf60b317b74d8652c7766c9272a7e] drm/amd/display: Apply ODM 2:1 policy for single display configuration
git bisect bad 88ef4c5bb36bf60b317b74d8652c7766c9272a7e
# good: [ff15cea338d2c78e0086d55c8a9dd637a5dd3ccc] drm/amd/display: expose additional modifier for DCN32/321
git bisect good ff15cea338d2c78e0086d55c8a9dd637a5dd3ccc
# good: [414e9f520e897818302a6b1729aa2dad8cc928ca] drm/amdkfd: Asynchronously free smi_client
git bisect good 414e9f520e897818302a6b1729aa2dad8cc928ca
# good: [4bdb9d6501763e83bacbf26846754c567773a1fb] drm/amdkfd: simplify vm_validate_pt_pd_bos
git bisect good 4bdb9d6501763e83bacbf26846754c567773a1fb
# good: [e72f03f4bdc4f3a251343cf343bce28c28cbac2a] drm/amd/display: Add missing registers for ACP
git bisect good e72f03f4bdc4f3a251343cf343bce28c28cbac2a
# bad: [90f33674a0756a6f0907b8f6350cec3f7be4032c] drm/amd/display: Prepare for new interfaces
git bisect bad 90f33674a0756a6f0907b8f6350cec3f7be4032c
# bad: [85f4bc0c333ceed24cbc9f69a2a77fab1ae3d4d1] drm/amd/display: Add SubVP required code
git bisect bad 85f4bc0c333ceed24cbc9f69a2a77fab1ae3d4d1
# first bad commit: [85f4bc0c333ceed24cbc9f69a2a77fab1ae3d4d1] drm/amd/display: Add SubVP required code