[Intel-gfx] [PATCH v3 7/8] drm: Connector helper function to release resources

[Pandiyan, Dhinakaran]

On Thu, 2017-02-16 at 09:09 +0000, Lankhorst, Maarten wrote:
> Daniel Vetter schreef op di 14-02-2017 om 20:51 [+0100]:
> > On Mon, Feb 13, 2017 at 10:26 PM, Pandiyan, Dhinakaran
> > <dhinakaran.pandiyan at intel.com> wrote:
> > > On Mon, 2017-02-13 at 09:05 +0000, Lankhorst, Maarten wrote:
> > > > Pandiyan, Dhinakaran schreef op do 09-02-2017 om 18:55 [+0000]:
> > > > > On Thu, 2017-02-09 at 09:01 +0000, Lankhorst, Maarten wrote:
> > > > > > 
> > > > > > Dhinakaran Pandiyan schreef op wo 08-02-2017 om 22:38 [-
> > > > > > 0800]:
> > > > > > > 
> > > > > > > Having a ->atomic_release callback is useful to release
> > > > > > > shared
> > > > > > > resources
> > > > > > > that get allocated in compute_config(). This function is
> > > > > > > expected
> > > > > > > to
> > > > > > > be
> > > > > > > called in the atomic_check() phase before new resources are
> > > > > > > acquired.
> > > > > > > 
> > > > > > > v2: Moved the caller hunk to this patch (Daniel)
> > > > > > > 
> > > > > > > Suggested-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> > > > > > > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at int
> > > > > > > el.com
> > > > > > > > 
> > > > > > > 
> > > > > > > ---
> > > > > > >  drivers/gpu/drm/drm_atomic_helper.c      | 19
> > > > > > > +++++++++++++++++++
> > > > > > >  include/drm/drm_modeset_helper_vtables.h | 13
> > > > > > > +++++++++++++
> > > > > > >  2 files changed, 32 insertions(+)
> > > > > > > 
> > > > > > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> > > > > > > b/drivers/gpu/drm/drm_atomic_helper.c
> > > > > > > index 8795088..92bd741 100644
> > > > > > > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > > > > > > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > > > > > > @@ -576,6 +576,25 @@ drm_atomic_helper_check_modeset(struct
> > > > > > > drm_device *dev,
> > > > > > >                 }
> > > > > > >         }
> > > > > > > 
> > > > > > > +       for_each_connector_in_state(state, connector,
> > > > > > > connector_state, i) {
> > > > > > > +               const struct drm_connector_helper_funcs
> > > > > > > *conn_funcs;
> > > > > > > +               struct drm_crtc_state *crtc_state;
> > > > > > > +
> > > > > > > +               conn_funcs = connector->helper_private;
> > > > > > > +               if (!conn_funcs->atomic_release)
> > > > > > > +                       continue;
> > > > > > > +
> > > > > > > +               if (!connector->state->crtc)
> > > > > > > +                       continue;
> > > > > > > +
> > > > > > > +               crtc_state =
> > > > > > > drm_atomic_get_existing_crtc_state(state, connector->state-
> > > > > > > > crtc);
> > > > > > > 
> > > > > > > +
> > > > > > > +               if (crtc_state->connectors_changed ||
> > > > > > > +                   crtc_state->mode_changed ||
> > > > > > > +                   (crtc_state->active_changed &&
> > > > > > > !crtc_state-
> > > > > > > > 
> > > > > > > > active))
> > > > > > > 
> > > > > > > +                       conn_funcs-
> > > > > > > >atomic_release(connector,
> > > > > > > connector_state);
> > > > > > > +       }
> > > > > > 
> > > > > > Could we deal with the VCPI state separately in
> > > > > > intel_modeset_checks,
> > > > > > like we do with dpll?
> > > > > 
> > > > > We'd want to release the VCPI slots before they are acquired in
> > > > > ->compute_config(). intel_modeset_checks() will be too late to
> > > > > release
> > > > > them. Are you suggesting both acquiring and releasing slots
> > > > > should be
> > > > > done in intel_modeset_checks()?
> > > > 
> > > > That makes things a bit more nasty. Maybe add a
> > > > conn_funcs->atomic_check that always gets called, something like
> > > > I did
> > > > below?
> > > > 
> > > > I'd love to use it for some atomic connector properties too.
> > > 
> > > 
> > > Adding and unconditionally calling conn_funcs->atomic_check()
> > > should be
> > > doable. It also follows the pattern we have for encoders and CRTCs.
> > > But
> > > I'll have to move the connector->state->crtc state checks inside
> > > the
> > > function.
> > 
> > Adding ->atomic_check that's unconditionally called sounds troubling,
> > because all the other ->atomic_check functions are _only_ called when
> > enabling stuff. ->atomic_release sounds much better to me, and from a
> > helper pov DK's patch above is the right place.
> 
> Having an atomic check would be nice for implementing connector
> properties. Some of them may need to be validated regardless of crtc.
> 

Can we add this later when we need state validation that is appropriate
for an ->atomic_check()? 

-DK

> I would really like to be able to do the validation in atomic_check
> instead of during the set_property callback. The state is not
> completely valid at that point yet, so this would be a logical place.
> 
> > If that place doesn't work for i915.ko, then we need our own callback
> > (like we already have with e.g. ->compute_config, we could do a
> > ->release_config). But if it's just cosmetics, then I don't see the
> > reason why we need to change this. On that issue: How exactly does
> > our
> > compute_config work if we haven't updated the routing (using the
> > above
> > helper) yet? That sounds like a pretty big misdesign on our side ...
> > -Daniel
> > 
> > 
> > > 
> > > -DK
> > > > > > 
> > > > > > 
> > > > > > Maybe implementing the relevant VCPI state could be done as
> > > > > > an
> > > > > > atomic
> > > > > > helper function too, so other atomic drivers can just plug it
> > > > > > in.
> > > > > > 
> > > > > 
> > > > > The idea was to reduce boilerplate in the drivers and use the
> > > > > private_obj state for different object types.
> > > > > 
> > > > > 
> > > > > > 
> > > > > > Not sure how doable this is, but if it's not too hard, then
> > > > > > it's
> > > > > > probably cleaner :)
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