Re: [PATCH v2 00/13] drm: Add generic helpers for HDMI scrambling

[Maxime Ripard <maxime@cerno.tech>]

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On Tue, Nov 30, 2021 at 09:29:09AM +0100, Daniel Vetter wrote:
> On Mon, Nov 29, 2021 at 11:07:41AM +0100, Maxime Ripard wrote:
> > On Fri, Nov 26, 2021 at 06:12:42PM +0100, Daniel Vetter wrote:
> > > On Fri, Nov 26, 2021 at 04:43:49PM +0100, Maxime Ripard wrote:
> > > > Hi Daniel,
> > > > 
> > > > On Fri, Nov 19, 2021 at 05:01:14PM +0100, Daniel Vetter wrote:
> > > > > On Thu, Nov 18, 2021 at 11:38:01AM +0100, Maxime Ripard wrote:
> > > > > > This is a follow-up of the work to support the interactions between the hotplug
> > > > > > and the scrambling support for vc4:
> > > > > > 
> > > > > > https://lore.kernel.org/dri-devel/20210507150515.257424-11-maxime@cerno.tech/
> > > > > > https://lore.kernel.org/dri-devel/20211025152903.1088803-10-maxime@cerno.tech/
> > > > > > 
> > > > > > Ville feedback was that the same discussion happened some time ago for i915,
> > > > > > and resulted in a function to do an full disable/enable cycle on reconnection
> > > > > > to avoid breaking the HDMI 2.0 spec.
> > > > > > 
> > > > > > This series improves the current scrambling support by adding generic helpers
> > > > > > for usual scrambling-related operations, and builds upon them to provide a
> > > > > > generic alternative to intel_hdmi_reset_link.
> > > > > 
> > > > > Out of curiosity, can we rebuild intel_hdmi_reset_link on top of these?
> > > > > Always better to have two drivers to actually show the helpers help, than
> > > > > just one.
> > > > 
> > > > Unfortunately, I don't have any Intel system I can test it on, and it
> > > > looks like the changes wouldn't be trivial.
> > > > 
> > > > Maybe we can use dw-hdmi instead?
> > > 
> > > Hm I guess so, maybe Ville can be motivated. Just figured since this seems
> > > at least inspired by i915 code.
> > 
> > It's not really the conversion to the new helper that I suspect would be
> > hard to do, but rather the usage of the connector state that we do, and
> > the scrambling computation, and how it's all tied together in i915.
> > 
> > It seems to be fairly different from drivers that just rely on the
> > atomic helpers, and I'm not really confident about changing that. But
> > yeah, I guess I can give it a try and rely on the CI.
> 
> Hm yeah if wiring through connector state to the right places is real work
> then skip the conversion. But I thought i915 modeset code has also gone
> through some of the state rollout that you've done for atomic helpers.

Maybe I'm just panicking without any particular reason, I'll give it a
try and will let you know

Maxime

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