Nouveau Driver Squeezes In Some Last Minute Minor Additions For Linux 6.8

Sent in overnight was this week's batch of DRM "fixes" for Linux 6.8 that included some mostly minor fixes plus a few notable but small patches to Nouveau, the upstream open-source NVIDIA DRM/KMS kernel driver.

This week's batch of DRM fixes included taking care of an FBDEV undefined reference issue on SPARC, fixing a sync object fence waiting issue, allowing the firmware to do the initial TILE configuration for the Intel iVPU NPU driver, fixing TV mode handling for the i915 driver, a suspend/resume fix for the AMDGPU driver, DCN 3.5 display fixes, and also a few fixes to the Intel Xe experimental DRM driver.

Back during the DRM feature pull for the Linux 6.8 merge window, there wasn't any notable Nouveau kernel driver changes given the limited developer resources currently around this open-source DRM/KMS driver. But now as part of this week's fixes are a few minor items.

First up is the recently talked about patch for allow optionally enabling the NVIDIA GSP mode by default on Turing GPUs and newer. Linux 6.7 brought the initial NVIDIA GSP mode that is optional for the GeForce RTX 20 / RTX 30 series while required by RTX 40 for any level of hardware accelerated support. The NVIDIA GPU System Processor firmware-driven power management is needed for better performance/re-clocking and all-around a better experience than the current non-GSP support on the RTX 20 series and newer.

But this GSP support in Nouveau requires making use of the NVIDIA GSP firmware binary blobs distributed now via linux-firmware.git. In part due to that and users potentially not having the firmware binaries, the GSP mode isn't enabled by default -- plus that it's still sort of experimental with just having been upstreamed in Linux 6.7.

But for Linux distributions that may be shipping the NVIDIA GSP firmware and are ready to go with their GSP'ed Nouveau support, the patch set to go into Linux 6.8-rc6 adds the "DRM_NOUVEAU_GSP_DEFAULT" Kconfig option for optionally enabling the GSP use by default.

In addition to that Nouveau GSP default option, Red Hat's David Airlie also authored and queued a patch adding a new ioctl to report vRAM usage to user-space. NOUVEAU_GETPARAM_VRAM_USED will return the currently used vRAM allocation and is of interest to the NVK Vulkan driver for querying.

The third Nouveau DRM driver addition that's part of this "fixes" pull is adding the NOUVEAU_GETPARAM_VRAM_BAR_SIZE ioctl for returning the vRAM BAR size. This returns the BAR resource size for user-space that is useful for ReBAR handling and is also sought for querying by the Mesa NVK Vulkan driver.

Those new Nouveau ioctls are trivial additions and don't risk regressing existing support and thus were submitted as part of this fixes work rather than waiting around for the v6.9 merge window.

The full list of DRM fixes for the week can be found via this Git pull that will presumably be merged to Linux Git later today.