On Mon, Jun 15, 2026 at 10:07:02AM +0200, Nicolas Frattaroli wrote: > On Saturday, 13 June 2026 08:57:29 Central European Summer Time Hans Verkuil > wrote: > > Hi Nicolas, > > > > On 11/06/2026 14:57, Nicolas Frattaroli wrote: > > > HDMI uses the DDC I2C bus for communicating various bits of link status > > > out of band with the actual HDMI video signal. This information can be > > > useful for debugging issues like questionable cables sabotaged by feline > > > teeth, Enthusiast Grade cables made of cow fencing wire, and other such > > > problems that ruin one's media viewing plans. > > > > > > Consequently, this series exposes various bits of pertinent information > > > from the SCDC protocol in an HDMI connector's debugfs. To continually > > > poll the link status, userspace can poll the debugfs file. > > > > Something is not quite right: I've been testing this series with my i915 > > based laptop with HDMI connector, and I never see the scdc_status file. > > And that's because CONFIG_DRM_BRIDGE_CONNECTOR is not set for my > > configuration. > > That's to be expected. i915 does not use bridge connectors, and neither > does amdgpu iirc. I am working on embedded boards that do use bridge > connectors, along with all the rest of the HDMI state helpers. > > Implementing something new in DRM usually involves having to triplicate > certain parts of the work in order to have i915 and amdgpu behave the > same as everyone else. > > > So I think you are creating the debugfs entry in the wrong place. > > I can't create it for all drm_connectors as Maxime suggested due to the > cyclical dependency that would create. If someone has any idea on how > to break that dependency cycle, I'm open to suggestions.
Back when we introduce the audio support, we floated the idea to de-midlayer this and turn it into a debugfs_init helper. We don't have a lot of users yet so it might be the best time to do so, and would solve your issue. Maxime
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