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I'm looking into an amdgpu implementation > and had some comments along the way. Will reply inline on respective > patches. > > On 2026-09-21 11:51, Nicolas Frattaroli wrote: > > A change in whether VRR is enabled or not on a CRTC will be of interest > > to any VRR implementation, as they may need to recalculate certain > > internal state in response. So far, this was handled ad-hoc in the > > drivers that implement VRR. > > > > Handle this in the common DRM atomic core by setting the mode_changed > > flag when this occurs. The rationale for using mode_changed is that VRR > > is deeply intertwined with the current mode with regards to its timing. > > Consequently, any component that cares about a mode change is likely > > also going to care about VRR being enabled/disabled. > > > > Signed-off-by: Nicolas Frattaroli > > --- > > drivers/gpu/drm/drm_atomic_helper.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > > index 9d006f98413a..0664d5779282 100644 > > --- a/drivers/gpu/drm/drm_atomic_helper.c > > +++ b/drivers/gpu/drm/drm_atomic_helper.c > > @@ -694,6 +694,12 @@ drm_atomic_helper_check_modeset(struct drm_device *dev, > > new_crtc_state->active_changed = true; > > } > > > > + if (old_crtc_state->vrr_enabled != new_crtc_state->vrr_enabled) { > > + drm_dbg_atomic(dev, "[CRTC:%d:%s] VRR changed\n", > > + crtc->base.id, crtc->name); > > + new_crtc_state->mode_changed = true; > > + } > > + > > I don't think this is the case for all hardware, at least not for amdgpu. > The parts in HW that adjust vtotal can be programmed without requiring > bandwidth recalculations or reprogramming of pipes. > > - Leo This is also the case for NVIDIA, it would be unfortunate if changes to vrr_enabled require allow_modeset=TRUE. > > > if (new_crtc_state->enable != has_connectors) { > > drm_dbg_atomic(dev, "[CRTC:%d:%s] enabled/connectors mismatch (%d/%d)\n", > > crtc->base.id, crtc->name, > > > >