On Wednesday, 23 September 2026 11:51:45 Central European Summer Time Michel Dänzer wrote: > On 9/21/26 17:51, Nicolas Frattaroli wrote: > > > > + * .. _VRR-MIN-NUMERATOR: > > + * > > + * "VRR_MIN_NUMERATOR": > > + * Default &drm_crtc integer property forming the numerator of a > > + * numerator/denominator pair of a frame rate to set as the minimum VRR > > + * target rate. Set to 0 to disable. > > + * > > + * "VRR_MIN_DENOMINATOR": > > + * Default &drm_crtc integer property forming the denominator of a > > + * numerator/denominator pair of a frame rate to set as the minimum VRR > > + * target rate. If :ref:`VRR_MIN_NUMERATOR <VRR-MIN-NUMERATOR>` is not > > + * zero, it must be non-zero. > > + * Otherwise, must also be zero. > > + * > > + * .. _VRR-MAX-NUMERATOR: > > + * > > + * "VRR_MAX_NUMERATOR": > > + * Default &drm_crtc integer property forming the numerator of a > > + * numerator/denominator pair of a frame rate to set as the maximum VRR > > + * target rate. Set to 0 to disable. > > + * > > + * "VRR_MAX_DENOMINATOR": > > + * Default &drm_crtc integer property forming the denominator of a > > + * numerator/denominator pair of a frame rate to set as the maximum VRR > > + * target rate. If :ref:`VRR_MAX_NUMERATOR <VRR-MAX-NUMERATOR>` is not > > + * zero, it must be non-zero. Otherwise, must also be zero. > > */ > > Is there a reason that DENOMINATOR must be 0 when the corresponding NUMERATOR > is? 0 divided by any number is still 0.
No, I think that's an arbitrary convention I settled on and don't enforce. I guess it should be "Otherwise, may also be zero", because the only situation I'm making userspace avoid is x/0 where x != 0. > > Either way, should these rules be enforced in drm_atomic_crtc_set_property? > > Or rather in atomic_check. Due to complicating factors like EDID, CinemaVRR, and QMS TFRmin/TFRmax, checking the properties for sensible values is done in the HDMI state helpers at the moment. If/when there is a similar mechanism for DP, we can probably factor the common parts out. I really do hope all drivers (including those that don't use the HDMI state helpers) can at least share the hdmi_validate_vrr() logic, but I haven't factored this out into an exported function yet because I don't know how similar the DisplayPort-equivalent mechanisms requirements are, or how much of the state derivation non-state-helper drivers (i.e. i915 and amdgpu) need. Kind regards, Nicolas Frattaroli
