Hi Boris,

Thank you for the patch.

On Thursday 02 Jun 2016 16:31:28 Boris Brezillon wrote:
> Adapt drm_pick_crtcs() and update_connector_routing() to fallback to
> drm_atomic_helper_best_encoder() if funcs->best_encoder() is NULL so
> that DRM drivers can leave this hook unassigned if they know they want
> to use drm_atomic_helper_best_encoder().

Could you please update include/drm/drm_modeset_helper_vtables.h to document 
this new behaviour ?

The only drawback I see in this patch is the additional object lookup 
performed by drm_atomic_helper_best_encoder() at runtime. I wonder if we could 
somehow cache the information, as the assignment can't change when there's a 
1:1 correspondence between encoders and connectors.

> Signed-off-by: Boris Brezillon <boris.brezil...@free-electrons.com>
> ---
>  drivers/gpu/drm/drm_atomic_helper.c |  4 +++-
>  drivers/gpu/drm/drm_fb_helper.c     | 13 ++++++++++++-
>  2 files changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c index f6a3350..849d029 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -300,8 +300,10 @@ update_connector_routing(struct drm_atomic_state
> *state, if (funcs->atomic_best_encoder)
>               new_encoder = funcs->atomic_best_encoder(connector,
>                                                        connector_state);
> -     else
> +     else if (funcs->best_encoder)
>               new_encoder = funcs->best_encoder(connector);
> +     else
> +             new_encoder = drm_atomic_helper_best_encoder(connector);
> 
>       if (!new_encoder) {
>               DRM_DEBUG_ATOMIC("No suitable encoder found for 
> [CONNECTOR:%d:%s]\n",
> diff --git a/drivers/gpu/drm/drm_fb_helper.c
> b/drivers/gpu/drm/drm_fb_helper.c index 7c2eb75..d44389a 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -2000,7 +2000,18 @@ static int drm_pick_crtcs(struct drm_fb_helper
> *fb_helper, my_score++;
> 
>       connector_funcs = connector->helper_private;
> -     encoder = connector_funcs->best_encoder(connector);
> +
> +     /*
> +      * If the DRM device implements atomic hooks and ->best_encoder() is
> +      * NULL we fallback to the default drm_atomic_helper_best_encoder()
> +      * helper.
> +      */
> +     if (fb_helper->dev->mode_config.funcs->atomic_commit &&
> +         !connector_funcs->best_encoder)
> +             encoder = drm_atomic_helper_best_encoder(connector);
> +     else
> +             encoder = connector_funcs->best_encoder(connector);
> +
>       if (!encoder)
>               goto out;

-- 
Regards,

Laurent Pinchart

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