On 19.07.25 17:52, Ville Syrjälä wrote: > On Sat, Jul 19, 2025 at 02:16:22AM +0200, Xaver Hugl wrote: >> Am Do., 10. Juli 2025 um 22:21 Uhr schrieb Ville Syrjälä >> <ville.syrj...@linux.intel.com>: >>> >>> On Mon, Jul 07, 2025 at 03:41:20PM +0000, Naveen Kumar wrote: >>>> Allow asynchronous page flips on planes that either lack a framebuffer or >>>> retain the same framebuffer, as long as no plane properties are modified. >>>> >>>> This avoids unnecessary failures in async flip paths when the update is >>>> effectively a no-op, improving compatibility with some compositors. >>> >>> IMO what we want to do is make the drm core filter out all the garbage >>> from the commit. That way the driver would only see the planes that are >>> supposed to actually participate in the async flip. >> >> That sounds like a good goal, but I think it'll need some extra care >> to avoid regressions. For example, "no-op" pageflips must still >> trigger pageflip events, and affect the refresh rate with adaptive >> sync. > > Not for async commit via the atomic ioctl. That's where I'd want > the filtering. > > For sync commit nothing can really be filtered by the core code > because side effects must be observed, and only the driver knows > what all the side effects are.
I agree with Xaver. In general, the DRM_MODE_PAGE_FLIP_ASYNC flag should affect only whether or not a plane assignment can take effect outside of vertical blank. That's true even with VRR. Current UAPI is that any commit with any state for a CRTC (or a plane bound to it) must trigger a refresh cycle on it ASAP with VRR. With DRM_MODE_PAGE_FLIP_EVENT, an event must be sent even for "no-op" changes, or user space may get stuck waiting for the event. -- Earthling Michel Dänzer \ GNOME / Xwayland / Mesa developer https://redhat.com \ Libre software enthusiast
