[RFCv1 10/12] drm: convert crtc to properties/state

[Rob Clark]

On Mon, Oct 7, 2013 at 9:39 AM, Ville Syrjälä
<ville.syrjala at linux.intel.com> wrote:
> On Sat, Oct 05, 2013 at 08:45:48PM -0400, Rob Clark wrote:
>> Break the mutable state of a crtc out into a separate structure
>> and use atomic properties mechanism to set crtc attributes.  This
>> makes it easier to have some helpers for crtc->set_property()
>> and for checking for invalid params.  The idea is that individual
>> drivers can wrap the state struct in their own struct which adds
>> driver specific parameters, for easy build-up of state across
>> multiple set_property() calls and for easy atomic commit or roll-
>> back.
>
> I'm not sure how we're going to handle the mismatch in the behaviour of
> the atomic modeset vs. the current setcrtc.
>
> The problem is that setcrtc ignore all kinds of conflicting
> crtc->connector assignments, and just overwrites whatever was there
> with the latest configuration. For the atomic case we want to return an
> error if there's a conflict.

Hmm, well currently we preserve the setcrtc behavior because it ends
up going through crtc helpers (or whatever the driver uses).  So
should be fine for setcrtc, but probably not what we want for atomic
ioctl.

I suppose we could solve some of this via internal flags, ie
.atomic_begin(dev, LEGACY_SETCRTC_CHECK_MODE)

it is a bit ugly, but it keeps the ugly in core and drivers don't have
to care as much about it (which is my main concern)

> And another thing is the DPMS handling. The
> current API forces DPMS on when you do a modeset, but for the atomic
> case I want to keep things nice and clean and avoid doing such silly
> things.

I guess the easy thing is to set DPMS property in setcrtc too ;-)

BR,
-R

> So I don't think we can simply convert the current modeset codepaths to
> call into the atomic code. We basically need another version of the
> check function, or another step that happens before .check only in the
> setcrtc case which eliminates the conflicts in a way that matches the
> current setcrtc behaviour.
>
> --
> Ville Syrjälä
> Intel OTC