On Wed, Nov 4, 2026 at 7:52 AM Ed Schofield <[email protected]> wrote: > > Hi Alex, hi Atharva, hi all, > > Alex, I'd like to withdraw my September v4 submission. I also don't support > applying v5 as posted or the simplified patch you attached later in this > thread. Please remove my Co-developed-by and Signed-off-by tags from both > versions. I no longer think deferring UCLK is the right approach for the > iMacs. > > I also excluded the MacBookPro16,1 (020f) from v4 deliberately because a > tester > found that with deferred UCLK it still hung after login, as it does without > the > patch [1], which seems to fit André's PPTable diagnosis. > > Since then, I've been working with Atharva to get his native-5K iMac support > upstream. His patch initializes the display before the SMU, which has also > prevented the boot failures without deferring UCLK. On my iMac20,1 (0218), 13 > of 20 warm boots failed with the upstream order; with display first, all 40 > boots passed [4]. Another tester reported one warm and one cold boot, both > successful, on a 0219 [2]. On an iMac20,2 (021a), changing only the > initialization order improved warm boot success from 11 out of 20 to 100 out > of > 100 [3]. His patch only applies to the iMac20,1 and iMac20,2, so it doesn't > fix > the 16,1 either. > > I don't think the iMacs and the MacBookPro16,1 have the same problem. The > iMacs fail while amdgpu is loading: the SMU stops responding to > EnableAllSmuFeatures (message 6), and the probe fails with -62. With the > display initialized first, the same message succeeds with UCLK included, > and the iMac boots normally. The 16,1 loads amdgpu without errors and hangs > later, after login, with or without deferred UCLK [1]. So deferring UCLK > seems to help the iMacs only because it moves the enable after display > init, and it doesn't help the MacBookPro16,1. > > I have prepared a draft patch with Atharva as author and me as co-developer, > incorporating his review feedback. It combines display-first initialization > and > native 5120x2880 support through two tiled connectors with suspend/resume and > display power-management changes. The current draft is here: > > https://github.com/edschofield/linux-t2-patches/blob/7273823e425200e9f371e9272e02ebf9abb6f1c2/7003-amdgpu-add-support-for-5K.patch > > This has passed some initial automated testing on my iMac20,1 but I need to do > more testing and get Atharva's final review and sign-off.
There are already patches on the list to support the 5K Macs: https://lists.freedesktop.org/archives/dri-devel/2026-November/610011.html Alex > > Alex, thanks for following up on the boot issue and checking with the Windows > team. > > Best regards, > Ed > > [1] > https://github.com/t2linux/linux-t2-patches/pull/61#issuecomment-5646139127 > [2] https://github.com/t2linux/wiki/issues/743#issuecomment-6083265811 > [3] https://github.com/t2linux/wiki/issues/743#issuecomment-6131809640 > [4] https://github.com/t2linux/wiki/issues/743#issuecomment-6163146905
