linux.git/drivers/gpu/drm/amd/display/dc/dml2, branch v6.14

drm/amd/display: Respect user's CONFIG_FRAME_WARN more for dml files

2025-02-04T22:47:10+00:00

Currently, there are several files in drm/amd/display that aim to have a
higher -Wframe-larger-than value to avoid instances of that warning with
a lower value from the user's configuration. However, with the way that
it is currently implemented, it does not respect the user's request via
CONFIG_FRAME_WARN for a higher stack frame limit, which can cause pain
when new instances of the warning appear and break the build due to
CONFIG_WERROR.

Adjust the logic to switch from a hard coded -Wframe-larger-than value
to only using the value as a minimum clamp and deferring to the
requested value from CONFIG_FRAME_WARN if it is higher.

Suggested-by: Harry Wentland 
Reported-by: Greg Kroah-Hartman 
Closes: https://lore.kernel.org/2025013003-audience-opposing-7f95@gregkh/
Signed-off-by: Nathan Chancellor 
Signed-off-by: Alex Deucher

drm/amd/display: Fix out-of-bound accesses

2025-02-03T17:12:04+00:00

[WHAT & HOW]
hpo_stream_to_link_encoder_mapping has size MAX_HPO_DP2_ENCODERS(=4),
but location can have size up to 6. As a result, it is necessary to
check location against MAX_HPO_DP2_ENCODERS.

Similiarly, disp_cfg_stream_location can be used as an array index which
should be 0..5, so the ASSERT's conditions should be less without equal.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3904
Reviewed-by: Austin Zheng 
Reviewed-by: Rodrigo Siqueira 
Signed-off-by: Alex Hung 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: mark static functions noinline_for_stack

2025-01-24T14:53:12+00:00

When compiling allmodconfig (CONFIG_WERROR=y) with clang-19, see the
following errors:

.../display/dc/dml2/display_mode_core.c:6268:13: warning: stack frame size (3128) exceeds limit (3072) in 'dml_prefetch_check' [-Wframe-larger-than]
.../display/dc/dml2/dml21/src/dml2_core/dml2_core_dcn4_calcs.c:7236:13: warning: stack frame size (3256) exceeds limit (3072) in 'dml_core_mode_support' [-Wframe-larger-than]

Mark static functions called by dml_prefetch_check() and
dml_core_mode_support() noinline_for_stack to avoid them become huge
functions and thus exceed the frame size limit.

A way to reproduce:
$ git checkout next-20250107
$ mkdir build_dir
$ export PATH=/tmp/llvm-19.1.6-x86_64/bin:$PATH
$ make LLVM=1 O=build_dir allmodconfig
$ make LLVM=1 O=build_dir drivers/gpu/drm/ -j

The way how it chose static functions to mark:
[0] Unset CONFIG_WERROR in build_dir/.config.
To get display_mode_core.o without errors.

[1] Get a function list called by dml_prefetch_check().
$ sed -n '6268,6711p' drivers/gpu/drm/amd/display/dc/dml2/display_mode_core.c \
  | sed -n -r 's/.*\W(\w+)\(.*/\1/p' | sort -u >/tmp/syms

[2] Get the non-inline function list.
Objdump won't show the symbols if they are inline functions.

$ make LLVM=1 O=build_dir drivers/gpu/drm/ -j
$ objdump -d build_dir/.../display_mode_core.o | \
  ./scripts/checkstack.pl x86_64 0 | \
  grep -f /tmp/syms | cut -d' ' -f2- >/tmp/orig

[3] Get the full function list.
Append "-fno-inline" to `CFLAGS_.../display_mode_core.o` in
drivers/gpu/drm/amd/display/dc/dml2/Makefile.

$ make LLVM=1 O=build_dir drivers/gpu/drm/ -j
$ objdump -d build_dir/.../display_mode_core.o | \
  ./scripts/checkstack.pl x86_64 0 | \
  grep -f /tmp/syms | cut -d' ' -f2- >/tmp/noinline

[4] Get the inline function list.
If a symbol only in /tmp/noinline but not in /tmp/orig, it is a good
candidate to mark noinline.

$ diff /tmp/orig /tmp/noinline

Chosen functions and their stack sizes:
CalculateBandwidthAvailableForImmediateFlip [display_mode_core.o]:144
CalculateExtraLatency [display_mode_core.o]:176
CalculateTWait [display_mode_core.o]:64
CalculateVActiveBandwithSupport [display_mode_core.o]:112
set_calculate_prefetch_schedule_params [display_mode_core.o]:48

CheckGlobalPrefetchAdmissibility [dml2_core_dcn4_calcs.o]:544
calculate_bandwidth_available [dml2_core_dcn4_calcs.o]:320
calculate_vactive_det_fill_latency [dml2_core_dcn4_calcs.o]:272
CalculateDCFCLKDeepSleep [dml2_core_dcn4_calcs.o]:208
CalculateODMMode [dml2_core_dcn4_calcs.o]:208
CalculateOutputLink [dml2_core_dcn4_calcs.o]:176

Signed-off-by: Tzung-Bi Shih 
Signed-off-by: Alex Deucher

drm/amd/display: Apply DML21 Patches

2025-01-10T17:12:23+00:00

[Why & How]
Add several DML21 fixes

Reviewed-by: Wenjing Liu 
Signed-off-by: Austin Zheng 
Signed-off-by: Tom Chung 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: Add SMU interface to get UMC count for dcn401

2025-01-10T17:04:43+00:00

[WHY&HOW]
BIOS table will not always contain accurate UMC channel info when
harvesting is enabled, so get the correct info from SMU.

Reviewed-by: Alvin Lee 
Signed-off-by: Dillon Varone 
Signed-off-by: Tom Chung 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: Initialize denominator defaults to 1

2025-01-10T17:04:06+00:00

[WHAT & HOW]
Variables, used as denominators and maybe not assigned to other values,
should be initialized to non-zero to avoid DIVIDE_BY_ZERO, as reported
by Coverity.

Reviewed-by: Austin Zheng 
Reviewed-by: Rodrigo Siqueira 
Signed-off-by: Alex Hung 
Signed-off-by: Tom Chung 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: DML2.1 Post-Si Cleanup

2025-01-10T17:00:34+00:00

[Why]
There are a few cleanup and refactoring tasks that need to be done
with the DML2.1 wrapper and DC interface to remove dependencies on
legacy structures and N-1 prototypes.

[How]
Implemented pipe_ctx->global_sync.
Implemented new functions to use pipe_ctx->hubp_regs and
pipe_ctx->global_sync:
- hubp_setup2
- hubp_setup_interdependent2
- Several other new functions for DCN 4.01 to support newer structures

Removed dml21_update_pipe_ctx_dchub_regs
Removed dml21_extract_legacy_watermark_set
Removed dml21_populate_pipe_ctx_dlg_param
Removed outdated dcn references in DML2.1 wrapper.

Reviewed-by: Austin Zheng 
Reviewed-by: Dillon Varone 
Signed-off-by: Rafal Ostrowski 
Signed-off-by: Tom Chung 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: Increase sanitizer frame larger than limit when compile testing with clang

2025-01-09T21:02:40+00:00

Commit 24909d9ec7c3 ("drm/amd/display: Overwriting dualDPP UBF values
before usage") added a new warning in dml2/display_mode_core.c when
building allmodconfig with clang:

  drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/display_mode_core.c:6268:13: error: stack frame size (3128) exceeds limit (3072) in 'dml_prefetch_check' [-Werror,-Wframe-larger-than]
   6268 | static void dml_prefetch_check(struct display_mode_lib_st *mode_lib)
        |             ^

Commit be4e3509314a ("drm/amd/display: DML21 Reintegration For Various
Fixes") introduced one in dml2_core/dml2_core_dcn4_calcs.c with the same
configuration:

  drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/dml21/src/dml2_core/dml2_core_dcn4_calcs.c:7236:13: error: stack frame size (3256) exceeds limit (3072) in 'dml_core_mode_support' [-Werror,-Wframe-larger-than]
   7236 | static bool dml_core_mode_support(struct dml2_core_calcs_mode_support_ex *in_out_params)
        |             ^

In the case of the first warning, the stack usage was already at the
limit at the parent change, so the offending change was rather
innocuous. In the case of the second warning, there was a rather
dramatic increase in stack usage compared to the parent:

  drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/dml21/src/dml2_core/dml2_core_dcn4_calcs.c:7032:13: error: stack frame size (2696) exceeds limit (2048) in 'dml_core_mode_support' [-Werror,-Wframe-larger-than]
   7032 | static bool dml_core_mode_support(struct dml2_core_calcs_mode_support_ex *in_out_params)
        |             ^

This is an unfortunate interaction between an issue with stack slot
reuse in LLVM that gets exacerbated by sanitization (which gets enabled
with all{mod,yes}config) and function calls using a much higher number
of parameters than is typical in the kernel, necessitating passing most
of these values on the stack.

While it is possible that there should be source code changes to address
these warnings, this code is difficult to modify for various reasons, as
has been noted in other changes that have occurred for similar reasons,
such as commit 6740ec97bcdb ("drm/amd/display: Increase frame warning
limit with KASAN or KCSAN in dml2").

Increase the frame larger than limit when compile testing with clang and
the sanitizers enabled to avoid this breakage in all{mod,yes}config, as
they are commonly used and valuable testing targets. While it is not the
best to hide this issue, it is not really relevant when compile testing,
as the sanitizers are commonly stressful on optimizations and they are
only truly useful at runtime, which COMPILE_TEST states will not occur
with the current build.

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202412121748.chuX4sap-lkp@intel.com/
Signed-off-by: Nathan Chancellor 
Signed-off-by: Alex Deucher

drm/amd/display: Ensure correct GFX tiling info passed to DML

2025-01-06T19:44:27+00:00

[Why]
To ensure DML validation receives the correct tiling information,
such as swizzle mode or array mode, based on the active GFX format

[How]
- For new GFX format passed swizzle_mode to DML.
- For legacy GFX format passed array_mode to DML.
- Dynamically determined the appropriate tiling info based on the
  active GFX format.

[Description]
This commit ensures that the correct GFX tiling information is passed
to DML. Depending on the active GFX format, the appropriate tiling info
is passed to DML. This change accommodates the different GFX formats
supported by latest platforms, ensuring compatibility and proper
DML validation.

Reviewed-by: Alvin Lee 
Signed-off-by: Karthi Kandasamy 
Signed-off-by: Roman Li 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher

drm/amd/display: correct type mismatches in comparisons in DML2

2025-01-06T19:44:26+00:00

[Why]
Comparisons were made between unsigned char and unsigned int.

[How]
Corrected by changing variable types.

Reviewed-by: Nicholas Kazlauskas 
Signed-off-by: Natanel Roizenman 
Signed-off-by: Roman Li 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher