More AMDGPU Patches For Linux 5.12 Point To First Sign Towards PCIe 5.0, FreeSync HDMI

Written by Michael Larabel in AMD on 4 February 2021 at 09:29 AM EST. 20 Comments
Sent in today to DRM-Next ahead of the Linux 5.12 kernel cycle were "fixes" but some interesting items worth noting in this batch.

Primary feature development is over for the DRM graphics drivers of new code they want in for Linux 5.12 since we are now late into the 5.11 release phase, but included as part of today's fixes pull request were a few more notable items.

Already in DRM-Next for this AMD Radeon open-source graphics driver with Linux 5.12 is various power management improvements, Radeon RX 6000 series OverDrive overclocking, FP16 enabled for more hardware, and other mostly lower-level changes.

Of this latest pull request focused on fixes, some last minute items worth pointing out include:

- FreeSync now being enabled for "A+A" configurations. This is for newer AMD APUs where they can scanout directly from the GTT, thus avoiding an extra bounce buffer in vRAM. With this pull request, FreeSync support is now enabled for these newer APUs.

- Restoring of the "set_fan_speed_percent" interface after it was disabled a few months ago for issues with some graphics cards.

- PCI Express 5.0 support is now a recognized PCIe capability. There isn't any new functionality wired up besides recognizing PCI Express Gen5 as a possible link speed. AMD has been supporting PCI Express 4.0 since the Radeon RX 5000 series while PCI Express 5.0 isn't expected to appear with AMD Radeon graphics cards until at least 2022. For punctual open-source support we'll hopefully see work on next-gen GPU support published before year's end and that would be when any interesting bits are revealed. This is just a tiny patch denoting work ultimately in that direction. Heck, elsewhere in the kernel is already patchwork beginning to recognize PCIe 6.0. PCI Express 5.0 provides 32 GT/s transfer rates.

- Enabling of user pointer "userptr" support when the AMDKFD compute driver is enabled.

- Various power management changes/fixes for VanGogh APUs.

- Support for DID 2.0 DSC pass-through. This is for some display panels that have active converters where currently prior to this support could just lead to black screens without this DID 2.0 parsing.

- 0x73A1 as a previously missing AMD RDNA 2 "Sienna Cichlid" device ID.

- As noted last week the AMD FreeSync HDMI patch is now queued. This is for the AMD specific FreeSync implementation over HDMI and not the standardized version found in HDMI 2.1+.

- A workaround for some DisplayPort to VGA dongles. Currently such dongles may end up only supporting 1440 x 900 when connected to a 1920 x 1080 display. The workaround corrects this behavior for some legacy dongles so the DP-VGA adapter can at least run at full HD (1080p).

Pretty good collection of fixes and other work queuing up for Linux 5.12! The Linux 5.12 merge window will formally get underway later this month. Linux 5.12 stable should be out in May. The full list of patches for this latest fixes pull request can be found on dri-devel.
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