On Thu, Mar 19, 2020 at 12:07:37PM +0200, Jani Nikula wrote:
> On Tue, 17 Mar 2020, Manasi Navare <manasi.d.navare@xxxxxxxxx> wrote:
> > This patch adds a hook in drm_connector_helper_funcs to get the
> > support of the driver for adaptive sync functionality.
> >
> > This can be called in the connector probe helper function after
> > the connector detect() and get_modes() hooks to also
> > query the adaptive sync support of the driver.
>
> I can obviously see that from the patch. But this does not explain at
> all *why* we need another hook to begin with, and why it neeeds to be
> called from ->fill_modes that is set to
> drm_helper_probe_single_connector_modes().
>
This needs to be called after get_modes that ends up populating the
monitor range after parsing the EDID.
I could have just modified the get_modes hook in the driver to set the
vrr capabilities but that doesnt go with the definition of get_modes() hook
which is purely to obtain modes from edid.
So i added a separate hook which will always return the vrr capabilities if this
hook exists in the driver everytime a connector probe happens.
Would you suggest this elsewhere or some other design?
I am open to better placement of this hook or reusing some other hook or
other suggestions for getting the vrr capabilities in the driver
Manasi
> > Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Cc: Harry Wentland <harry.wentland@xxxxxxx>
> > Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@xxxxxxx>
> > Signed-off-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/drm_probe_helper.c | 4 ++++
> > include/drm/drm_modeset_helper_vtables.h | 16 ++++++++++++++++
> > 2 files changed, 20 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> > index 576b4b7dcd89..4403817bfb02 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -482,6 +482,10 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
> >
> > count = (*connector_funcs->get_modes)(connector);
> >
> > + /* Get the Adaptive Sync Support if helper exists */
> > + if (*connector_funcs->get_adaptive_sync_support)
> > + (**connector_funcs->get_adaptive_sync_support)(connector);
> > +
>
> This is in the middle of a sequence figuring out the modes. First
> ->get_modes, then fallback to other mechanisms. Certainly we don't want
> to do something else in the middle.
>
> > /*
> > * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
> > * override/firmware EDID.
> > diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
> > index 7c20b1c8b6a7..0b203fdd25df 100644
> > --- a/include/drm/drm_modeset_helper_vtables.h
> > +++ b/include/drm/drm_modeset_helper_vtables.h
> > @@ -1079,6 +1079,22 @@ struct drm_connector_helper_funcs {
> > struct drm_writeback_job *job);
> > void (*cleanup_writeback_job)(struct drm_writeback_connector *connector,
> > struct drm_writeback_job *job);
> > +
> > + /**
> > + * @get_adaptive_sync_support:
> > + *
> > + * This hook is used by the probe helper to get the driver's support
> > + * for adaptive sync or variable refresh rate.
> > + * This is called from drm_helper_probe_single_connector_modes()
> > + * This is called after the @get_modes hook so that the connector modes
> > + * are already obtained and EDID is parsed to obtain the monitor
> > + * range descriptor information.
> > + *
> > + * This hook is optional and defined only for the drivers and on
> > + * connectors that advertise adaptive sync support.
> > + *
> > + */
> > + void (*get_adaptive_sync_support)(struct drm_connector *connector);
> > };
> >
> > /**
>
> --
> Jani Nikula, Intel Open Source Graphics Center
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