The purpose of this series is to allow drivers to avoid unnecessarily delaying page flips, by explicitly telling the driver which vblank seqno a flip is supposed to take effect in.
Patch 1 sets the target to the vblank seqno after the current one when the DRM_IOCTL_MODE_PAGE_FLIP ioctl is called, preserving the ioctl contract with existing userspace.
Patches 2-4 take advantage of this in the amdgpu and radeon drivers, by allowing a flip to be programmed and executed during the target vertical blank period (or a later one).
Patch 6 extends the ioctl with new flags, which allow userspace to explicitly specify the target vblank seqno. This can also avoid delaying flips in some cases where we are already in the target vertical blank period when the ioctl is called.
[PATCH 1/6] drm: Add page_flip_target CRTC hook [PATCH 2/6] drm/amdgpu: Provide page_flip_target hook [PATCH 3/6] drm/amdgpu: Set MASTER_UPDATE_MODE to 0 again [PATCH 4/6] drm/radeon: Provide page_flip_target hook [PATCH 5/6] drm/radeon: Set MASTER_UPDATE_MODE to 0 again [PATCH 6/6] drm: Add DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE/RELATIVE