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().
> 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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