News: 0001634894

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AMDGPU HDMI 2.1 FRL To Be Initially Disabled-By-Default

([Radeon] 26 Minutes Ago Disabled By Default)


One of the most exciting developments in recent times for the open-source AMDGPU kernel graphics driver is [1]HDMI 2.1 FRL support for the AMDGPU driver along with [2]Display Stream Compression support as they work toward providing full HDMI 2.1 support for this open-source AMD Radeon driver. The details how AMD managed to pull this feat off given prior resistance from the HDMI Forum remains to be confirmed, but it's moving ahead and out today is the latest iteration of the HDMI 2.1 FRL+DSC patches.

This sixth iteration of the HDMI FRL and FRL DSC patches was posted a few minutes ago to the mailing list. There are a few bug fixes but most notable is now making FRL disabled-by-default initially. Users wanting to enable HDMI 2.1 Fixed Rate Link support for higher refresh rates / resolutions will need to boot their Linux kernel with the amdgpu.dc_feature_mask=0x400 to enable the functionality.

FRL support is being disabled by default until the Variable Refresh Rate (VRR) functionality is in place. Without VRR support, it could be considered a regression for existing users with FRL-capable displays. Once the HDMI VRR support is ready, the plan is to have the support enabled by default. So the amdgpu.dc_feature_mask=0x400 necessity will hopefully be short-lived.

Those interested can check out the [3]v6 patches on the mailing list. Here's to hoping it is submitted still in time for the upcoming Linux v7.2 cycle.



[1] https://www.phoronix.com/news/AMDGPU-HDMI-2.1-FRL-Patches

[2] https://www.phoronix.com/news/HDMI-2.1-DSC-AMDGPU-FRL

[3] https://lists.freedesktop.org/archives/amd-gfx/2026-May/145009.html



=== ALL USERS PLEASE NOTE ========================

CAR and CDR now return extra values.

The function CAR now returns two values. Since it has to go to the trouble
to figure out if the object is carcdr-able anyway, we figured you might as
well get both halves at once. For example, the following code shows how to
destructure a cons (SOME-CONS) into its two slots (THE-CAR and THE-CDR):

(MULTIPLE-VALUE-BIND (THE-CAR THE-CDR) (CAR SOME-CONS) ...)

For symmetry with CAR, CDR returns a second value which is the CAR of the
object. In a related change, the functions MAKE-ARRAY and CONS have been
fixed so they don't allocate any storage except on the stack. This should
hopefully help people who don't like using the garbage collector because
it cold boots the machine so often.