In the Linux kernel, the following vulnerability has been resolved:
drm/i915/vrr: Configure VRR timings after enabling TRANS_DDI_FUNC_CTL
Apparently ICL may hang with an MCE if we write TRANS_VRR_VMAX/FLIPLINE
before enabling TRANS_DDI_FUNC_CTL.
Personally I was only able to reproduce a hang (on an Dell XPS 7390
2-in-1) with an external display connected via a dock using a dodgy
type-C cable that made the link training fail. After the failed
link training the machine would hang. TGL seemed immune to the
problem for whatever reason.
BSpec does tell us to configure VRR after enabling TRANS_DDI_FUNC_CTL
as well. The DMC firmware also does the VRR restore in two stages:
- first stage seems to be unconditional and includes TRANS_VRR_CTL
and a few other VRR registers, among other things
- second stage is conditional on the DDI being enabled,
and includes TRANS_DDI_FUNC_CTL and TRANS_VRR_VMAX/VMIN/FLIPLINE,
among other things
So let's reorder the steps to match to avoid the hang, and
toss in an extra WARN to make sure we don't screw this up later.
BSpec: 22243
(cherry picked from commit 93f3a267c3dd4d811b224bb9e179a10d81456a74)
drm/i915/vrr: Configure VRR timings after enabling TRANS_DDI_FUNC_CTL
Apparently ICL may hang with an MCE if we write TRANS_VRR_VMAX/FLIPLINE
before enabling TRANS_DDI_FUNC_CTL.
Personally I was only able to reproduce a hang (on an Dell XPS 7390
2-in-1) with an external display connected via a dock using a dodgy
type-C cable that made the link training fail. After the failed
link training the machine would hang. TGL seemed immune to the
problem for whatever reason.
BSpec does tell us to configure VRR after enabling TRANS_DDI_FUNC_CTL
as well. The DMC firmware also does the VRR restore in two stages:
- first stage seems to be unconditional and includes TRANS_VRR_CTL
and a few other VRR registers, among other things
- second stage is conditional on the DDI being enabled,
and includes TRANS_DDI_FUNC_CTL and TRANS_VRR_VMAX/VMIN/FLIPLINE,
among other things
So let's reorder the steps to match to avoid the hang, and
toss in an extra WARN to make sure we don't screw this up later.
BSpec: 22243
(cherry picked from commit 93f3a267c3dd4d811b224bb9e179a10d81456a74)
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||
| Linux | Linux | affected |
|
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Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 13 May 2026 15:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: drm/i915/vrr: Configure VRR timings after enabling TRANS_DDI_FUNC_CTL Apparently ICL may hang with an MCE if we write TRANS_VRR_VMAX/FLIPLINE before enabling TRANS_DDI_FUNC_CTL. Personally I was only able to reproduce a hang (on an Dell XPS 7390 2-in-1) with an external display connected via a dock using a dodgy type-C cable that made the link training fail. After the failed link training the machine would hang. TGL seemed immune to the problem for whatever reason. BSpec does tell us to configure VRR after enabling TRANS_DDI_FUNC_CTL as well. The DMC firmware also does the VRR restore in two stages: - first stage seems to be unconditional and includes TRANS_VRR_CTL and a few other VRR registers, among other things - second stage is conditional on the DDI being enabled, and includes TRANS_DDI_FUNC_CTL and TRANS_VRR_VMAX/VMIN/FLIPLINE, among other things So let's reorder the steps to match to avoid the hang, and toss in an extra WARN to make sure we don't screw this up later. BSpec: 22243 (cherry picked from commit 93f3a267c3dd4d811b224bb9e179a10d81456a74) | |
| Title | drm/i915/vrr: Configure VRR timings after enabling TRANS_DDI_FUNC_CTL | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-13T15:08:26.763Z
Reserved: 2026-05-01T14:12:56.011Z
Link: CVE-2026-43477
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-05-13T16:16:50.807
Modified: 2026-05-13T16:16:50.807
Link: CVE-2026-43477
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.