Hi,
On 4 December 2015 at 08:46, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote:
> + /*
> + * Reject event generation for when a CRTC is off and stays off. It
> + * wouldn't be hard to implement this, but userspace has a track record
> + * of happily burning through 100% cpu (or worse, crash) when the
> + * display pipe is suspended. To avoid all that fun just reject updates
> + * that ask for events since likely that indicates a bug in the
> + * compositors drawing loop. This is consistent with the vblank ioctl
> + * which also rejects service on a disabled pipe.
> + */
Sorry to keep whingeing, but this isn't actually related to event
generation. To the best of my knowledge, this change does a few
things. Firstly, comments the check above (enforcing that (flags &
ALLOW_MODESET) == {crtcs}->allow_modeset), which is good. But the
comment is incorrect, because whether or not an event is requested is
wholly unrelated. Secondly, it disables allow_modeset on pageflip,
which shouldn't be changing DPMS stage (good!). Thirdly, it enforces
something like the above statement on pageflips, except again it has
no regard to events: it just enforces the no-DPMS-on-flip rule, for
which event generation is a subset.
If you fix the above comment to more accurately note that this just
enforces that you need the ALLOW_MODESET flag to change active, mode
or connector routing, and (as Thierry asked), add a comment below to
note that we enforce existing no-DPMS-on-flip semantics in the helper,
then you're welcome to my R-b. But please don't mention events in the
new comment. :)
Cheers,
Daniel
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