AMD is adding HDMI 2.1 support for Linux. That’s good news for the Steam Machine.

AMD 正在为 Linux 添加 HDMI 2.1 支持，这对 Steam Machine 来说是个好消息。

Last year, we noted how the long-standing vagaries of HDMI licensing and open source AMD driver development combined to prevent the upcoming Steam Machine from receiving official support for the HDMI 2.1 display standard. 去年，我们曾指出，HDMI 许可协议长期以来的不确定性，加上开源 AMD 驱动程序的开发进度，导致即将推出的 Steam Machine 无法获得 HDMI 2.1 显示标准的官方支持。

Now, though, it seems that AMD is making real progress on adding full HDMI 2.1 compliance to its Linux amdgpu driver in the near future. In patch series notes for an amdgpu driver update posted on Friday (and noticed by Phoronix), AMD’s Harry Wentland says that the company is finally adding HDMI FRL (Fixed Rate Link) support to the popular Linux display driver. 不过现在看来，AMD 在不久的将来为 Linux amdgpu 驱动程序添加完整的 HDMI 2.1 合规性方面取得了实质性进展。在周五发布的一份 amdgpu 驱动更新补丁说明中（由 Phoronix 发现），AMD 的 Harry Wentland 表示，公司终于要为这款流行的 Linux 显示驱动添加 HDMI FRL（固定速率链路）支持了。

That’s the feature that allows for higher bandwidth on compatible HDMI cables compared to the TMDS standard found on HDMI 2.0 and earlier. That in turn enables direct support for higher resolutions, dynamic HDR, and features like Variable Refresh Rate that aren’t supported in HDMI 2.0. 该功能允许兼容的 HDMI 线缆在带宽上超越 HDMI 2.0 及更早版本所使用的 TMDS 标准。这进而实现了对更高分辨率、动态 HDR 以及 HDMI 2.0 不支持的可变刷新率（VRR）等功能的直接支持。

Wentland notes that this update is still just “a representative subset of HDMI compliance,” in part because it is missing the code to support the Display Stream Compression (DSC) that allows for even higher resolutions and frame rates up to 10K at 100 Hz. But Wentland adds that DSC support “is still being tested and will be sent out later,” and that “a full compliance run” for HDMI 2.1 is “in the works.” Wentland 指出，此次更新目前仅是“HDMI 合规性的一个代表性子集”，部分原因是它缺少对显示流压缩（DSC）的支持代码，而 DSC 是实现更高分辨率和高达 10K 100Hz 帧率的关键。但 Wentland 补充说，DSC 支持“仍在测试中，稍后会发布”，并且 HDMI 2.1 的“全面合规性测试”也“正在进行中”。

An AMD driver developer with the handle agd5f also commented on Phoronix, noting that “a full implementation [of HDMI 2.1] will ultimately be available once the patches are ready and have completed compliance testing.” 一位代号为 agd5f 的 AMD 驱动开发人员也在 Phoronix 上评论称：“一旦补丁准备就绪并完成合规性测试，[HDMI 2.1] 的完整实现最终将会提供。”

This is all good news for Steam Machine buyers and other Linux gamers who want to finally make use of high-end display features that were first standardized in 2017. Valve says it has been using workarounds like chroma subsampling and AMD Freesync support to squeeze better Steam Machine performance out of the HDMI 2.0 bandwidth currently supported by AMD’s Linux drivers. 对于 Steam Machine 的购买者以及其他希望最终用上 2017 年就已标准化的高端显示功能的 Linux 游戏玩家来说，这无疑是个好消息。Valve 表示，他们一直使用色度抽样（chroma subsampling）和 AMD Freesync 支持等变通方法，试图在 AMD Linux 驱动目前支持的 HDMI 2.0 带宽限制下，压榨出 Steam Machine 更好的性能。

The coming introduction of full HDMI 2.1 support in amdgpu should obviate the need for those workarounds, though. It’s unclear whether the HDMI Forum’s original legal issues with any open source implementation of HDMI 2.1 have been resolved or if that organization will allow Linux devices to advertise as HDMI 2.1-compliant (we’ve reached out to the HDMI Forum for comment). 不过，随着 amdgpu 即将引入完整的 HDMI 2.1 支持，这些变通方法将不再必要。目前尚不清楚 HDMI 论坛此前针对任何开源 HDMI 2.1 实现所提出的法律问题是否已经解决，也不清楚该组织是否会允许 Linux 设备宣传其符合 HDMI 2.1 标准（我们已联系 HDMI 论坛寻求置评）。

For now, though, it seems clear that AMD is finally comfortable adding the HDMI 2.1 features it says have been ready and waiting to its Linux drivers for years now. In December, Valve said that “we’ve been working on trying to unblock things” regarding AMD drivers, and it’s nice to see those efforts finally bearing fruit on AMD’s side. 但就目前而言，AMD 显然终于可以放心地将其声称已准备好并等待多年的 HDMI 2.1 功能添加到 Linux 驱动中了。去年 12 月，Valve 曾表示“我们一直在努力解决 AMD 驱动程序方面的阻碍”，很高兴看到这些努力终于在 AMD 一方结出了硕果。