On Mon, May 06, 2024 at 09:52:35PM +0300, Juha-Pekka Heikkila wrote: > These patches introduce I915_FORMAT_MOD_4_TILED_XE2_CCS modifier, which, > from the kernel's perspective, behaves similarly to `I915_FORMAT_MOD_4_TILED`. > This new modifier is primarily intended for user space to effectively monitor > compression status, especially when dealing with a mix of compressed and > uncompressed buffers. > > The addition of this modifier facilitates user space in managing compression > status, particularly when utilizing both compressed and uncompressed buffers > concurrently. To leverage compression for these buffers, user space > applications must configure the appropriate Page Attribute Table (PAT) index. > Display engine will treat all Tile4 as if it were compressed under all > circumstances on Xe2 architecture. I may have missed some discussion about this, but I thought the previous consensus was that we didn't want/need new modifiers for compression on Xe2? If a userspace client (or the display hardware) receives a buffer of unknown origin and unknown compression status, it's always fine to select a compressed PAT when binding the buffer to read since even for uncompressed buffers the CCS metadata will accurately reflect the compression status. Unlike Xe1, where generating content without compression enabled would leave random garbage in the FlatCCS area, Xe2 will set the corresponding FlatCCS to '0x0' for each block, indicating uncompressed data. Can you explain more what the benefit of handling these modifiers explicitly is? Matt > > Notably, this patch series omits support for X-tiled CCS and linear CCS > for Xe2, neither of which is supported by display engine. X-tiled CCS > offers stateless compression making it less likely to be extensively > utilized. Linear CCS does possess state, but currently lacks expected users. > > These patches aim to enhance the flexibility and efficiency of handling > compressed and uncompressed buffers in Xe driver, particularly > catering to the specific requirements of the Xe2 architecture. > > Juha-Pekka Heikkila (3): > drm/fourcc: define Intel Xe2 related tile4 ccs modifier > drm/xe/display: allow creation of case I915_FORMAT_MOD_4_TILED_XE2_CCS > type framebuffer > drm/i915/display: allow creation of case > I915_FORMAT_MOD_4_TILED_XE2_CCS type framebuffer > > drivers/gpu/drm/i915/display/intel_display.c | 1 + > drivers/gpu/drm/i915/display/intel_fb.c | 10 ++++++++++ > drivers/gpu/drm/i915/display/skl_universal_plane.c | 4 +++- > drivers/gpu/drm/xe/display/xe_plane_initial.c | 1 + > include/uapi/drm/drm_fourcc.h | 12 ++++++++++++ > 5 files changed, 27 insertions(+), 1 deletion(-) > > -- > 2.43.2 > -- Matt Roper Graphics Software Engineer Linux GPU Platform Enablement Intel Corporation
