This series adds new format modifiers for 8 and 16-bit formats on GB20x GPUs, preventing them from mistakenly sharing block-linear surfaces using these formats with prior GPUs that use a different layout.
There are a few ways the parameteric format modifier definition could have been altered to handle the new layouts: -The GOB Height and Page Kind field has a reserved value that could have been used. However, the GOB height and page kind enums did not change relative to prior chips, so this is sort of a lie. However, this is the least-invasive change. -An entirely new field could have been added. This seems inappropriate given the presence of an existing appropriate field. The advantage here is it avoids splitting the sector layout field across two bitfields. The chosen approach is the logically consistent one, but has the downside of being the most complex, and that it causes the DRM_FORMAT_MOD_NVIDIA_BLOCK_LINEAR_2D() macro to evaluate its 's' parameter twice. However, utilizing simple helper functions in client code when accessing the parameteric format modifier fields easily addresses the complexity, and I have audited the relevant code and do not believe the double evaluation should cause any problems in practice. Tested on GB20x and TU10x cards using the following: -kmscube w/NVK+Zink built with these patches applied: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36336 with various manually specified formats and both manually specified and automatically selected modifiers. -drmfmtmods, a tiny test program that lists modifiers: https://github.com/cubanismo/drmfmtmods Changes since the RFC version here: https://lore.kernel.org/nouveau/20250703223658.1457-1-jajo...@nvidia.com/ -Dropped the helper macros & static inlines in drm_fourcc.h as requested by Faith Ekstrand, who noted these aren't helpful for UMD code, which is all written in rust now. I may re- introduce some of these in a subsequent series, but we both agreed we do not want to delay progress on the modifiers themselves while we debate the details of those cometic details. -Reserved an extra bit for future sector layouts. -Fixed handling of linear modifiers on GB20x and NV5x/G8x/G9x/GT2xx chips. James Jones (3): drm: define NVIDIA DRM format modifiers for GB20x drm/nouveau/disp: Always accept linear modifier drm/nouveau: Advertise correct modifiers on GB20x drivers/gpu/drm/nouveau/dispnv50/disp.c | 3 ++ drivers/gpu/drm/nouveau/dispnv50/disp.h | 1 + drivers/gpu/drm/nouveau/dispnv50/wndw.c | 25 ++++++++++++++-- drivers/gpu/drm/nouveau/dispnv50/wndwca7e.c | 33 +++++++++++++++++++++ include/uapi/drm/drm_fourcc.h | 25 ++++++++++------ 5 files changed, 76 insertions(+), 11 deletions(-) -- 2.50.1
