Re: [PATCH v4 23/27] drm: Add passive_vrr_disabled property to crtc

[Tomasz Pakuła]

On Tue, 2026-02-17 at 09:21 +0100, Michel Dänzer wrote:
> On 2/16/26 17:45, Tomasz Pakuła wrote:
> > Many TVs and other HDMI sinks suffer from blanking and possibly other
> > glitches when VRR is toggled. With VRR present on such sinks and
> > vrr_on_desktop enabled, they behave like the signal is always variable,
> > even in fixed refresh rate situations. DisplayPort and eDP enforce
> > seamless VRR transitions but HDMI unfortunately doesn't.
> > 
> > Keep VRR toggled if it's supported and not explicitly disabled. It can
> > be used for any VRR sinks, but this is mainly targeted for HDMI.
> > 
> > Functionally, for an end user, this is the same as normal, fixed refresh
> > rate mode. The only difference is that sink is kept in VRR state which
> > enables seamless transitions into/out of variable refresh rate.
> > 
> > Basically, the driver shouldn't change it's behavior around VRR_ENABLED
> > set to false, jut keep sending info packets/frames with VRR/FreeSync/
> > G-Sync/HDMI VRR active.
> > 
> > Enabled by default for sinks that claim it's support
> 
> Having a negation term like "disabled" in the property name can be confusing (as it involves double negation when the property value is 0) and is better avoided.
> 

I understand that and felt a little cheaty by doing this but I couldn't
for the life of my figure out how to make it so a driver could override
this by default, before the compositor will set this. Would a "set"
function work, just like for "capable" properties?
 
I 100% believe this "Passive VRR" for HDMI should be the default and
helps massively but I'm not even that convinced if this must be user
configurable. Alex asked to make it a property, but In the end, it's not
something thsdat can be controlled on other OSes. I still believe that
users should be able to change this somehow, but if amdgpu module
setting wasn't a good fit, I don't know what is.

In the end, I can just yeet all this completely and hardcode
freesync_on_desktop = true for HDMI like it's done in the windows
driver.