linux-stable.git/drivers/gpu/drm/amd/display/dc, branch v6.18

drm/amd/display: Check NULL before accessing

2025-11-26T17:17:38+00:00

[WHAT]
IGT kms_cursor_legacy's long-nonblocking-modeset-vs-cursor-atomic
fails with NULL pointer dereference. This can be reproduced with
both an eDP panel and a DP monitors connected.

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: Oops: 0000 [#1] SMP NOPTI
 CPU: 13 UID: 0 PID: 2960 Comm: kms_cursor_lega Not tainted
6.16.0-99-custom #8 PREEMPT(voluntary)
 Hardware name: AMD ........
 RIP: 0010:dc_stream_get_scanoutpos+0x34/0x130 [amdgpu]
 Code: 57 4d 89 c7 41 56 49 89 ce 41 55 49 89 d5 41 54 49
 89 fc 53 48 83 ec 18 48 8b 87 a0 64 00 00 48 89 75 d0 48 c7 c6 e0 41 30
 c2 <48> 8b 38 48 8b 9f 68 06 00 00 e8 8d d7 fd ff 31 c0 48 81 c3 e0 02
 RSP: 0018:ffffd0f3c2bd7608 EFLAGS: 00010292
 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffd0f3c2bd7668
 RDX: ffffd0f3c2bd7664 RSI: ffffffffc23041e0 RDI: ffff8b32494b8000
 RBP: ffffd0f3c2bd7648 R08: ffffd0f3c2bd766c R09: ffffd0f3c2bd7760
 R10: ffffd0f3c2bd7820 R11: 0000000000000000 R12: ffff8b32494b8000
 R13: ffffd0f3c2bd7664 R14: ffffd0f3c2bd7668 R15: ffffd0f3c2bd766c
 FS:  000071f631b68700(0000) GS:ffff8b399f114000(0000)
knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000000 CR3: 00000001b8105000 CR4: 0000000000f50ef0
 PKRU: 55555554
 Call Trace:
 
 dm_crtc_get_scanoutpos+0xd7/0x180 [amdgpu]
 amdgpu_display_get_crtc_scanoutpos+0x86/0x1c0 [amdgpu]
 ? __pfx_amdgpu_crtc_get_scanout_position+0x10/0x10[amdgpu]
 amdgpu_crtc_get_scanout_position+0x27/0x50 [amdgpu]
 drm_crtc_vblank_helper_get_vblank_timestamp_internal+0xf7/0x400
 drm_crtc_vblank_helper_get_vblank_timestamp+0x1c/0x30
 drm_crtc_get_last_vbltimestamp+0x55/0x90
 drm_crtc_next_vblank_start+0x45/0xa0
 drm_atomic_helper_wait_for_fences+0x81/0x1f0
 ...

Cc: Mario Limonciello 
Cc: Alex Deucher 
Reviewed-by: Aurabindo Pillai 
Signed-off-by: Alex Hung 
Signed-off-by: Alex Deucher 
(cherry picked from commit 621e55f1919640acab25383362b96e65f2baea3c)
Cc: stable@vger.kernel.org

Revert "drm/amd/display: Move setup_stream_attribute"

2025-11-26T17:16:58+00:00

This reverts commit 2681bf4ae8d24df950138b8c9ea9c271cd62e414.

This results in a blank screen on the HDMI port on some systems.
Revert for now so as not to regress 6.18, can be addressed
in 6.19 once the issue is root caused.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4652
Cc: Sunpeng.Li@amd.com
Cc: ivan.lipski@amd.com
Signed-off-by: Alex Deucher 
(cherry picked from commit d0e9de7a81503cdde37fb2d37f1d102f9e0f38fb)

drm/amd/display: Clear the CUR_ENABLE register on DCN20 on DPP5

2025-11-18T17:07:50+00:00

[Why]
On DCN20 & DCN30, the 6th DPP's & HUBP's are powered on permanently and
cannot be power gated. Thus, when dpp_reset() is invoked for the DPP5,
while it's still powered on, the cached cursor_state
(dpp_base->pos.cur0_ctl.bits.cur0_enable)
and the actual state (CUR0_ENABLE) bit are unsycned. This can cause a
double cursor in full screen with non-native scaling.

[How]
Force disable cursor on DPP5 on plane powerdown for ASICs w/ 6 DPPs/HUBPs.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4673
Reviewed-by: Aric Cyr 
Signed-off-by: Ivan Lipski 
Tested-by: Dan Wheeler 
Signed-off-by: Alex Deucher 
(cherry picked from commit 79b3c037f972dcb13e325a8eabfb8da835764e15)
Cc: stable@vger.kernel.org

drm/amd/display: Increase DPCD read retries

2025-11-18T17:06:34+00:00

[Why]
Empirical measurement of some monitors that fail to read EDID while
booting shows that the number of retries with a 30ms delay between
tries is as high as 16.

[How]
Increase number of retries to 20.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4672
Reviewed-by: Alex Hung 
Signed-off-by: Mario Limonciello (AMD) 
Signed-off-by: Ivan Lipski 
Tested-by: Dan Wheeler 
Signed-off-by: Alex Deucher 
(cherry picked from commit ad1c59ad7cf74ec06e32fe2c330ac1e957222288)
Cc: stable@vger.kernel.org

drm/amd/display: Move sleep into each retry for retrieve_link_cap()

2025-11-18T17:03:42+00:00

[Why]
When a monitor is booting it's possible that it isn't ready to retrieve
link caps and this can lead to an EDID read failure:

```
[drm:retrieve_link_cap [amdgpu]] *ERROR* retrieve_link_cap: Read receiver caps dpcd data failed.
amdgpu 0000:c5:00.0: [drm] *ERROR* No EDID read.
```

[How]
Rather than msleep once and try a few times, msleep each time.  Should
be no changes for existing working monitors, but should correct reading
caps on a monitor that is slow to boot.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4672
Reviewed-by: Alex Hung 
Signed-off-by: Mario Limonciello (AMD) 
Signed-off-by: Ivan Lipski 
Tested-by: Dan Wheeler 
Signed-off-by: Alex Deucher 
(cherry picked from commit 669dca37b3348a447db04bbdcbb3def94d5997cc)
Cc: stable@vger.kernel.org

drm/amd/display: Prevent Gating DTBCLK before It Is Properly Latched

2025-11-18T16:52:18+00:00

[why]
1. With allow_0_dtb_clk enabled, the time required to latch DTBCLK to 600 MHz
depends on the SMU. If DTBCLK is not latched to 600 MHz before set_mode completes,
gating DTBCLK causes the DP2 sink to lose its clock source.

2. The existing DTBCLK gating sequence ungates DTBCLK based on both pix_clk and ref_dtbclk,
but gates DTBCLK when either pix_clk or ref_dtbclk is zero.
pix_clk can be zero outside the set_mode sequence before DTBCLK is properly latched,
which can lead to DTBCLK being gated by mistake.

[how]
Consider both pixel_clk and ref_dtbclk when determining when it is safe to gate DTBCLK;
this is more accurate.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4701
Fixes: 5949e7c4890c ("drm/amd/display: Enable Dynamic DTBCLK Switch")
Reviewed-by: Charlene Liu 
Reviewed-by: Aurabindo Pillai 
Signed-off-by: Fangzhi Zuo 
Signed-off-by: Roman Li 
Tested-by: Dan Wheeler 
Signed-off-by: Alex Deucher 
(cherry picked from commit d04eb0c402780ca037b62a6aecf23b863545ebca)
Cc: stable@vger.kernel.org

drm/amd/display: Fix black screen with HDMI outputs

2025-11-04T18:24:40+00:00

[Why & How]
This fixes the black screen issue on certain APUs with HDMI,
accompanied by the following messages:

amdgpu 0000:c4:00.0: amdgpu: [drm] Failed to setup vendor info
                     frame on connector DP-1: -22
amdgpu 0000:c4:00.0: [drm] Cannot find any crtc or sizes [drm]
                     Cannot find any crtc or sizes

Fixes: 489f0f600ce2 ("drm/amd/display: Fix DVI-D/HDMI adapters")
Suggested-by: Timur Kristóf 
Reviewed-by: Harry Wentland 
Signed-off-by: Alex Hung 
Signed-off-by: Ray Wu 
Tested-by: Daniel Wheeler 
Signed-off-by: Alex Deucher 
(cherry picked from commit 678c901443a6d2e909e3b51331a20f9d8f84ce82)

drm/amd/display: Don't program BLNDGAM_MEM_PWR_FORCE when CM low-power is disabled on DCN30

2025-10-28T15:01:44+00:00

Before commit 33056a97ae5e ("drm/amd/display: Remove double checks for
`debug.enable_mem_low_power.bits.cm`"), dpp3_program_blnd_lut(NULL)
checked the low-power debug flag before calling
dpp3_power_on_blnd_lut(false).

After commit 33056a97ae5e ("drm/amd/display: Remove double checks for
`debug.enable_mem_low_power.bits.cm`"), dpp3_program_blnd_lut(NULL)
unconditionally calls dpp3_power_on_blnd_lut(false). The BLNDGAM power
helper writes BLNDGAM_MEM_PWR_FORCE when CM low-power is disabled, causing
immediate SRAM power toggles instead of deferring at vupdate. This can
disrupt atomic color/LUT sequencing during transitions between
direct scanout and composition within gamescope's DRM backend on
Steam Deck OLED.

To fix this, leave the BLNDGAM power state unchanged when low-power is
disabled, matching dpp3_power_on_hdr3dlut and dpp3_power_on_shaper.

Fixes: 33056a97ae5e ("drm/amd/display: Remove double checks for `debug.enable_mem_low_power.bits.cm`")
Signed-off-by: Matthew Schwartz 
Reviewed-by: Harry Wentland 
Reviewed-by: Mario Limonciello 
Signed-off-by: Mario Limonciello 
Signed-off-by: Alex Deucher 
(cherry picked from commit 13ff4f63fcddfc84ec8632f1443936b00aa26725)
Cc: stable@vger.kernel.org

drm/amd/display: increase max link count and fix link->enc NULL pointer access

2025-10-21T13:50:27+00:00

[why]
1.) dc->links[MAX_LINKS] array size smaller than actual requested.
max_connector + max_dpia + 4 virtual = 14.
increase from 12 to 14.

2.) hw_init() access null LINK_ENC for dpia non display_endpoint.

Cc: Mario Limonciello 
Cc: Alex Deucher 
Reviewed-by: Meenakshikumar Somasundaram 
Reviewed-by: Chris Park 
Signed-off-by: Charlene Liu 
Signed-off-by: Aurabindo Pillai 
Signed-off-by: Alex Deucher 
(cherry picked from commit d7f5a61e1b04ed87b008c8d327649d184dc5bb45)
Cc: stable@vger.kernel.org

drm/amd/display: Fix NULL pointer dereference

2025-10-21T13:45:33+00:00

[Why]
On a mst branch with multi display setup, dc context is obselete
after updating the first stream. Referencing the same dc context
for the next stream update to fetch dc pointer leads to NULL
pointer dereference.

[How]
Get the dc pointer from the link rather than context.

Cc: Mario Limonciello 
Cc: Alex Deucher 
Reviewed-by: Charlene Liu 
Signed-off-by: Meenakshikumar Somasundaram 
Signed-off-by: Aurabindo Pillai 
Signed-off-by: Alex Deucher 
(cherry picked from commit dc69b48988b171d6ccb3a083607e4dff015e2c0d)
Cc: stable@vger.kernel.org