Re: [PATCH 0/5] drm/amd/display: Reduce stack usage for clang

[Rodrigo Siqueira Jordao <Rodrigo.Siqueira@amd.com>]

On 2022-08-30 16:34, Nathan Chancellor wrote:
> Hi all,
> 
> This series aims to address the following warnings, which are visible
> when building x86_64 allmodconfig with clang after commit 3876a8b5e241
> ("drm/amd/display: Enable building new display engine with KCOV
> enabled").
> 
>      drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn30/display_mode_vba_30.c:3542:6: error: stack frame size (2200) exceeds limit (2048) in 'dml30_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
>      void dml30_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
>          ^
>      1 error generated.
> 
>      drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn31/display_mode_vba_31.c:3908:6: error: stack frame size (2216) exceeds limit (2048) in 'dml31_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
>      void dml31_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
>          ^
>      1 error generated.
> 
>      drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:1721:6: error: stack frame size (2152) exceeds limit (2048) in 'dml32_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
>      void dml32_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
>          ^
>      1 error generated.
> 
> This series is based on commit b3235e8635e1 ("drm/amd/display: clean up
> some inconsistent indentings"). These warnings are fatal for
> allmodconfig due to CONFIG_WERROR so ideally, I would like to see these
> patches cherry-picked to a branch targeting mainline to allow our builds
> to go back to green. However, since this series is not exactly trivial
> in size, I can understand not wanting to apply these to mainline during
> the -rc cycle. If they cannot be cherry-picked to mainline, I can add a
> patch raising the value of -Wframe-larger-than for these files that can
> be cherry-picked to 6.0/mainline then add a revert of that change as the
> last patch in the stack so everything goes back to normal for -next/6.1.
> I am open to other options though!
> 
> I have built this series against clang 16.0.0 (ToT) and GCC 12.2.0 for
> x86_64. It has seen no runtime testing, as my only test system with AMD
> graphics is a Renoir one, which as far as I understand it uses DCN 2.1.
> 
> Nathan Chancellor (5):
>    drm/amd/display: Reduce number of arguments of
>      dml32_CalculateWatermarksMALLUseAndDRAMSpeedChangeSupport()
>    drm/amd/display: Reduce number of arguments of
>      dml32_CalculatePrefetchSchedule()
>    drm/amd/display: Reduce number of arguments of dml31's
>      CalculateWatermarksAndDRAMSpeedChangeSupport()
>    drm/amd/display: Reduce number of arguments of dml31's
>      CalculateFlipSchedule()
>    drm/amd/display: Mark dml30's UseMinimumDCFCLK() as noinline for stack
>      usage
> 
>   .../dc/dml/dcn30/display_mode_vba_30.c        |   2 +-
>   .../dc/dml/dcn31/display_mode_vba_31.c        | 420 +++++-------------
>   .../dc/dml/dcn32/display_mode_vba_32.c        | 236 +++-------
>   .../dc/dml/dcn32/display_mode_vba_util_32.c   | 323 ++++++--------
>   .../dc/dml/dcn32/display_mode_vba_util_32.h   |  51 +--
>   5 files changed, 318 insertions(+), 714 deletions(-)
> 
> 
> base-commit: b3235e8635e1dd7ac1a27a73330e9880dfe05154

Hi Nathan,

First of all, thanks a lot for your patchset!

Sorry for the delay; it took me more time than I expected to review and 
run a couple of tests in this patchset (most of them were IGT). Anyway, 
I'm good with this change; this series is:

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>

And I applied it to amd-staging-drm-next.

We will run some extra tests this week; if we find some issues, I'll 
debug them.

Also, thanks, Maíra, for checking this patch as well.

Best Regards,
Siqueira