Re: [PATCH] drm/amd/amdgpu: Add 5K Support for iMac20,1 and iMac20,2

[Alex Deucher]

On Wed, Nov 4, 2026 at 3:02 PM Atharva Tiwari
<atharvatiwarilinuxdev@xxxxxxxxx> wrote:
>
> > What's the reason for this change?
>
> This is the code that fixes the SMU boot issue, that we discussed eariler:
>
> https://lore.kernel.org/all/20261103160553.1431-1-atharvatiwarilinuxdev@xxxxxxxxx/
>
> Its confirmed to be 0x4F1 as OCLP enables it, and with OCLP and no patches it booted fine.
>
> I plan to add 5K support to efi libstub or something in the future, hence the TODO, so we
> get 5K in simpledrm and get rid of this not good looking quirk.

That sounds like a separate logical change from the rest of the patch.
If changing the order of the init sequence fixes the SMU UCLK issue,
that should be a separate patch from the changes to enable the 5K
display.  That said, I'm not really keen on this change.  Can you dig
further and figure out what the actual issue is?  There are now 3
separate slightly different fixes for this for people with various
Macs:
1. Enabling UCLK DPM in late init
2. Using the UCLK states from the UMC DPM table
3. Changing the init order for specific Mac models

Alex