[Intel-gfx] [PATCH] drm/i915: force full modeset if the connector is in DPMS OFF mode

Daniel Vetter daniel at ffwll.ch
Fri May 3 18:50:43 CEST 2013

On Fri, May 3, 2013 at 6:28 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> Not quite. It was added afterwards, I know for it is one of my mistakes
> that I belatedly recognised as trying to workaround a bug in UXA. And we
> then layered on further bugs to try and patch up the glaring holes then
> introduced.

I've done some digging around and found some cool stuff, but no change
which introduce the original bug that we've never consulted dpms state
in drm_crtc_helper_set_mode but just blindly enabled encoders. Most of
the commits I've dug out try to paper over that mismatch by updating
dpms state, too. E.g. bf9dc102 which was then fixed up a bit in
811aaa55 but I don't see any mention of someone explicitly kill dpms

Of course for DP support we've started to add dpms state checks to our
dp encoder (since double-enable kills DP). Then duplicated the
drm_connector->dpms into our own intel_dp->dpms state since the crtc
helpers liked to frob around with dpms in a rather ill-defined way.
But that's just hilarity and flailing around on top, nothing that I
could see fundamentally changed that a full setcrtc implicitly enabled
the encoders/crtc hw. And since we have our own modeset code that all
disappeared (since a full modeset simply force-updates the dpms state
to reflect reality).

But nowhere have a found a commit to support your claim, just lots of
flailing around due to the ill-defined semantics of this all. Care to
do some more digging?

Thanks, Daniel
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

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