CVE-2026-43191drm/amd/display: Adjust PHY FSM transition to TX_EN-to-PLL_ON for TMDS on DCN35

Official description

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Adjust PHY FSM transition to TX_EN-to-PLL_ON for TMDS on DCN35 [Why] A backport of the change made for DCN401 that addresses an issue where we turn off the PHY PLL when disabling TMDS output, which causes the OTG to remain stuck. The OTG being stuck can lead to a hang in the DCHVM's ability to ACK invalidations when it thinks the HUBP is still on but it's not receiving global sync. The transition to PLL_ON needs to be atomic as there's no guarantee that the thread isn't pre-empted or is able to complete before the IOMMU watchdog times out. [How] Backport the implementation from dcn401 back to dcn35. There's a functional difference in when the eDP output is disabled in dcn401 code so we don't want to utilize it directly.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/be43c36ac13d3a158791566c9fe60511022b7a15
• https://git.kernel.org/stable/c/02b033e18e08a1d0b53cf540196688c82af60a2f
• https://git.kernel.org/stable/c/d1f7ceb00e8956ff6d183b7b45ef4e73c96f4c51
• https://git.kernel.org/stable/c/75372d75a4e23783583998ed99d5009d555850da