linux-stable.git/drivers/gpu/drm/amd/display, branch v6.18.32

drm/amd/display: Change dither policy for 10 bpc output back to dithering

2026-05-17T15:15:32+00:00

commit d65bfb1782304b03862c8c725fac608015dffd36 upstream.

Commit d5df648ec830 ("drm/amd/display: Change dither policy for 10bpc to
round") degraded display of 12 bpc color precision output to 10 bpc sinks
by switching 10 bpc output from dithering to "truncate to 10 bpc".

I don't find the argumentation in that commit convincing, but the
consequences highly unfortunate, especially for applications that
require effective > 10 bpc precision output of > 10 bpc framebuffers.

The argument wasn't something strong like "there are hardware design
defects or limitations which require us to work around broken dithering
to 10 bpc", or "there are some special use cases which do require
truncation to 10 bpc", but essentially "at some point in the past we
used truncation in Polaris/Vega times and it looks like it got
inadvertently changed for Navi, so let's do that again". I couldn't find
evidence for that in the git commit logs for this. The commit message also
acknowledges that using dithering "...makes some sense for FP16...
...but not for ARGB2101010 surfaces..."

The problem with this is that it makes fp16 surfaces, and especially
rgba16 fixed point surfaces, less useful. These are now well
supported by Mesa 25.3 and later via OpenGL + EGL, Vulkan/WSI, and by
OSS AMDVLK Vulkan/WSI/display, and also by GNOME 50 mutter under Wayland,
and they used to provide more than 10 bpc effective precision at the
output.

Even for 8 or 10 bpc surfaces, the color pipeline behind the framebuffer,
e.g., gamma tables, CTM, can be used for color correction and will
benefit from an effective > 10 bpc output precision via dithering,
retaining some precision that would get lost on the way through the
pipeline, e.g., due to non-linear gamma functions.

Scientific apps rely on this for > 10 bpc display precision. Truncating
to 10 bpc, instead of dithering the pipeline internal 12 bpc precision
down to 10 bpc, causes a serious loss of precision. This also creates the
undesirable and slightly absurd situation that using a cheap monitor
with only 8 bpc input and display panel will yield roughly 12 bpc
precision via dithering from 12 -> 8 bpc, whereas investment into a
more expensive monitor with 10 bpc input and native 10 bpc display will
only yield 10 bpc, even if a fp16 or rgb16 framebuffer and/or a properly
set up color pipeline (gamma tables, CTM's etc. with more than 10 bpc out
precision) would allow effective 12 bpc precision output.

Therefore this patch proposes reverting that commit and going back to
dithering down to 10 bpc, consistent with the behaviour for 6 bpc or 8 bpc
output.

Successfully tested on AMD Polaris DCE 11.2 and Raven Ridge DCN 1.0 with
a native 10 bpc capable monitor, outputting a RGBA16 unorm framebuffer and
measuring resulting color precision with a photometer. No apparent visual
artifacts or problems were observed, and effective precision was measured
to be 12 bpc again, as expected.

Fixes: d5df648ec830 ("drm/amd/display: Change dither policy for 10bpc to round")
Signed-off-by: Mario Kleiner 
Tested-by: Mario Kleiner 
Cc: stable@vger.kernel.org
Cc: Aric Cyr 
Cc: Anthony Koo 
Cc: Rodrigo Siqueira 
Cc: Krunoslav Kovac 
Cc: Alex Deucher 
Reported-by: Mario Kleiner 
Signed-off-by: Harry Wentland 
Reviewed-by: Harry Wentland 
Signed-off-by: Alex Deucher 
Signed-off-by: Greg Kroah-Hartman

drm/amd: Fix set but not used warnings

2026-05-07T04:11:47+00:00

commit 46791d147d3ab3262298478106ef2a52fc7192e2 upstream.

There are many set but not used warnings under drivers/gpu/drm/amd when
compiling with the latest upstream mainline GCC:

  drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c:305:18: warning: variable ‘p’ set but not used [-Wunused-but-set-variable=]
  drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h:103:26: warning: variable ‘internal_reg_offset’ set but not used [-Wunused-but-set-variable=]
  ...
  drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h:164:26: warning: variable ‘internal_reg_offset’ set but not used [-Wunused-but-set-variable=]
  ...
  drivers/gpu/drm/amd/amdgpu/../display/dc/dc_dmub_srv.c:445:13: warning: variable ‘pipe_idx’ set but not used [-Wunused-but-set-variable=]
  drivers/gpu/drm/amd/amdgpu/../display/dc/dc_dmub_srv.c:875:21: warning: variable ‘pipe_idx’ set but not used [-Wunused-but-set-variable=]

Remove the variables actually not used or add __maybe_unused attribute for
the variables actually used to fix them, compile tested only.

Signed-off-by: Tiezhu Yang 
Signed-off-by: Alex Deucher 
Signed-off-by: Greg Kroah-Hartman

drm/amd/display: Fix DCE LVDS handling

2026-04-11T12:26:51+00:00

[ Upstream commit 90d239cc53723c1a3f89ce08eac17bf3a9e9f2d4 ]

LVDS does not use an HPD pin so it may be invalid.  Handle
this case correctly in link encoder creation.

Fixes: 7c8fb3b8e9ba ("drm/amd/display: Add hpd_source index check for DCE60/80/100/110/112/120 link encoders")
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/5012
Cc: Srinivasan Shanmugam 
Cc: Roman Li 
Reviewed-by: Roman Li 
Reviewed-by: Srinivasan Shanmugam 
Signed-off-by: Alex Deucher 
(cherry picked from commit 3b5620f7ee688177fcf65cf61588c5435bce1872)
Cc: stable@vger.kernel.org
[ removed unrelated VGA connector block absent from stable and split combined null/bounds check into separate guard and ternary ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

drm/amd/display: Fix NULL pointer dereference in dcn401_init_hw()

2026-04-11T12:26:34+00:00

commit e927b36ae18b66b49219eaa9f46edc7b4fdbb25e upstream.

dcn401_init_hw() assumes that update_bw_bounding_box() is valid when
entering the update path. However, the existing condition:

  ((!fams2_enable && update_bw_bounding_box) || freq_changed)

does not guarantee this, as the freq_changed branch can evaluate to true
independently of the callback pointer.

This can result in calling update_bw_bounding_box() when it is NULL.

Fix this by separating the update condition from the pointer checks and
ensuring the callback, dc->clk_mgr, and bw_params are validated before
use.

Fixes the below:
../dc/hwss/dcn401/dcn401_hwseq.c:367 dcn401_init_hw() error: we previously assumed 'dc->res_pool->funcs->update_bw_bounding_box' could be null (see line 362)

Fixes: ca0fb243c3bb ("drm/amd/display: Underflow Seen on DCN401 eGPU")
Cc: Daniel Sa 
Cc: Alvin Lee 
Cc: Roman Li 
Cc: Alex Hung 
Cc: Tom Chung 
Cc: Dan Carpenter 
Cc: Aurabindo Pillai 
Signed-off-by: Srinivasan Shanmugam 
Reviewed-by: Alex Hung 
Signed-off-by: Alex Deucher 
(cherry picked from commit 86117c5ab42f21562fedb0a64bffea3ee5fcd477)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

drm/amd/display: Fix drm_edid leak in amdgpu_dm

2026-04-02T11:23:23+00:00

commit 37c2caa167b0b8aca4f74c32404c5288b876a2a3 upstream.

[WHAT]
When a sink is connected, aconnector->drm_edid was overwritten without
freeing the previous allocation, causing a memory leak on resume.

[HOW]
Free the previous drm_edid before updating it.

Reviewed-by: Roman Li 
Signed-off-by: Alex Hung 
Signed-off-by: Chuanyu Tseng 
Signed-off-by: Alex Deucher 
(cherry picked from commit 52024a94e7111366141cfc5d888b2ef011f879e5)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

drm/amd/display: Do not skip unrelated mode changes in DSC validation

2026-04-02T11:23:13+00:00

[ Upstream commit aed3d041ab061ec8a64f50a3edda0f4db7280025 ]

Starting with commit 17ce8a6907f7 ("drm/amd/display: Add dsc pre-validation in
atomic check"), amdgpu resets the CRTC state mode_changed flag to false when
recomputing the DSC configuration results in no timing change for a particular
stream.

However, this is incorrect in scenarios where a change in MST/DSC configuration
happens in the same KMS commit as another (unrelated) mode change. For example,
the integrated panel of a laptop may be configured differently (e.g., HDR
enabled/disabled) depending on whether external screens are attached. In this
case, plugging in external DP-MST screens may result in the mode_changed flag
being dropped incorrectly for the integrated panel if its DSC configuration
did not change during precomputation in pre_validate_dsc().

At this point, however, dm_update_crtc_state() has already created new streams
for CRTCs with DSC-independent mode changes. In turn,
amdgpu_dm_commit_streams() will never release the old stream, resulting in a
memory leak. amdgpu_dm_atomic_commit_tail() will never acquire a reference to
the new stream either, which manifests as a use-after-free when the stream gets
disabled later on:

BUG: KASAN: use-after-free in dc_stream_release+0x25/0x90 [amdgpu]
Write of size 4 at addr ffff88813d836524 by task kworker/9:9/29977

Workqueue: events drm_mode_rmfb_work_fn
Call Trace:
 
 dump_stack_lvl+0x6e/0xa0
 print_address_description.constprop.0+0x88/0x320
 ? dc_stream_release+0x25/0x90 [amdgpu]
 print_report+0xfc/0x1ff
 ? srso_alias_return_thunk+0x5/0xfbef5
 ? __virt_addr_valid+0x225/0x4e0
 ? dc_stream_release+0x25/0x90 [amdgpu]
 kasan_report+0xe1/0x180
 ? dc_stream_release+0x25/0x90 [amdgpu]
 kasan_check_range+0x125/0x200
 dc_stream_release+0x25/0x90 [amdgpu]
 dc_state_destruct+0x14d/0x5c0 [amdgpu]
 dc_state_release.part.0+0x4e/0x130 [amdgpu]
 dm_atomic_destroy_state+0x3f/0x70 [amdgpu]
 drm_atomic_state_default_clear+0x8ee/0xf30
 ? drm_mode_object_put.part.0+0xb1/0x130
 __drm_atomic_state_free+0x15c/0x2d0
 atomic_remove_fb+0x67e/0x980

Since there is no reliable way of figuring out whether a CRTC has unrelated
mode changes pending at the time of DSC validation, remember the value of the
mode_changed flag from before the point where a CRTC was marked as potentially
affected by a change in DSC configuration. Reset the mode_changed flag to this
earlier value instead in pre_validate_dsc().

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/5004
Fixes: 17ce8a6907f7 ("drm/amd/display: Add dsc pre-validation in atomic check")
Signed-off-by: Yussuf Khalil 
Reviewed-by: Harry Wentland 
Signed-off-by: Alex Deucher 
(cherry picked from commit cc7c7121ae082b7b82891baa7280f1ff2608f22b)
Signed-off-by: Sasha Levin

drm/amd: fix dcn 2.01 check

2026-03-25T10:10:45+00:00

[ Upstream commit 39f44f54afa58661ecae9c27e15f5dbce2372892 ]

The ASICREV_IS_BEIGE_GOBY_P check always took precedence, because it includes all chip revisions upto NV_UNKNOWN.

Fixes: 54b822b3eac3 ("drm/amd/display: Use dce_version instead of chip_id")
Signed-off-by: Andy Nguyen 
Signed-off-by: Alex Deucher 
(cherry picked from commit 9c7be0efa6f0daa949a5f3e3fdf9ea090b0713cb)
Signed-off-by: Sasha Levin

drm/amd/display: Fix DisplayID not-found handling in parse_edid_displayid_vrr()

2026-03-25T10:10:45+00:00

[ Upstream commit 2323b019651ad81c20a0f7f817c63392b3110652 ]

parse_edid_displayid_vrr() searches the EDID extension blocks for a
DisplayID extension before parsing the dynamic video timing range.

The code previously checked whether edid_ext was NULL after the search
loop. However, edid_ext is assigned during each iteration of the loop,
so it will never be NULL once the loop has executed. If no DisplayID
extension is found, edid_ext ends up pointing to the last extension
block, and the NULL check does not correctly detect the failure case.

Instead, check whether the loop completed without finding a matching
DisplayID block by testing "i == edid->extensions". This ensures the
function exits early when no DisplayID extension is present and avoids
parsing an unrelated EDID extension block.

Also simplify the EDID validation check using "!edid ||
!edid->extensions".

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:13079 parse_edid_displayid_vrr() warn: variable dereferenced before check 'edid_ext' (see line 13075)

Fixes: a638b837d0e6 ("drm/amd/display: Fix refresh rate range for some panel")
Cc: Roman Li 
Cc: Alex Hung 
Cc: Jerry Zuo 
Cc: Sun peng Li 
Cc: Tom Chung 
Cc: Dan Carpenter 
Cc: Aurabindo Pillai 
Signed-off-by: Srinivasan Shanmugam 
Reviewed-by: Tom Chung 
Signed-off-by: Alex Deucher 
(cherry picked from commit 91c7e6342e98c846b259c57273436fdea4c043f2)
Signed-off-by: Sasha Levin

drm/amd/display: Wrap dcn32_override_min_req_memclk() in DC_FP_{START, END}

2026-03-25T10:10:36+00:00

commit ebe82c6e75cfc547154d0fd843b0dd6cca3d548f upstream.

[Why]
The dcn32_override_min_req_memclk function is in dcn32_fpu.c, which is
compiled with CC_FLAGS_FPU into FP instructions.  So when we call it we
must use DC_FP_{START,END} to save and restore the FP context, and
prepare the FP unit on architectures like LoongArch where the FP unit
isn't always on.

Reported-by: LiarOnce 
Fixes: ee7be8f3de1c ("drm/amd/display: Limit DCN32 8 channel or less parts to DPM1 for FPO")
Signed-off-by: Xi Ruoyao 
Reviewed-by: Alex Hung 
Signed-off-by: Alex Deucher 
(cherry picked from commit 25bb1d54ba3983c064361033a8ec15474fece37e)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

drm/amd/display: Fallback to boot snapshot for dispclk

2026-03-19T15:08:39+00:00

commit 30d937f63bd19bbcaafa4b892eb251f8bbbf04ef upstream.

[WHY & HOW]
If the dentist is unavailable, fallback to reading CLKIP via the boot
snapshot to get the current dispclk.

Reviewed-by: Nicholas Kazlauskas 
Signed-off-by: Dillon Varone 
Signed-off-by: Alex Hung 
Cc: Mario Limonciello 
Cc: Alex Deucher 
Tested-by: Dan Wheeler 
Signed-off-by: Alex Deucher 
(cherry picked from commit 2ab77600d1e55a042c02437326d3c7563e853c6c)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman