[Intel-gfx] [PATCH] drm/fbdev: Fallback to non tiled mode if all tiles not present

[Daniel Vetter]

On Thu, Oct 31, 2019 at 02:48:39PM -0700, Manasi Navare wrote:
> In case of tiled displays, if we hotplug just one connector,
> fbcon currently just selects the preferred mode and if it is
> tiled mode then that becomes a problem if rest of the tiles are
> not present.
> So in the fbdev driver on hotplug when we probe the client modeset,
> we we dont find all the connectors for all tiles, then on a connector
> with one tile, just fallback to the first available non tiled mode
> to display over a single connector.
> 
> Suggested-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Suggested-by: Dave Airlie <airlied at redhat.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Dave Airlie <airlied at redhat.com>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>

Hm, should we mayb have a slight timeout first to wait for the 2nd
connector? Otherwise lots of flickering going on when plugging in one of
these screens ...
-Daniel

> ---
>  drivers/gpu/drm/drm_client_modeset.c | 29 ++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
> index 895b73f23079..e28a723587db 100644
> --- a/drivers/gpu/drm/drm_client_modeset.c
> +++ b/drivers/gpu/drm/drm_client_modeset.c
> @@ -114,6 +114,20 @@ drm_client_find_modeset(struct drm_client_dev *client, struct drm_crtc *crtc)
>  	return NULL;
>  }
>  
> +static struct drm_display_mode *
> +drm_connector_fallback_non_tiled_mode(struct drm_connector *connector)
> +{
> +	struct drm_display_mode *mode;
> +
> +	list_for_each_entry(mode, &connector->modes, head) {
> +		if (mode->hdisplay == connector->tile_h_size &&
> +		    mode->vdisplay == connector->tile_v_size)
> +			continue;
> +		return mode;
> +	}
> +	return NULL;
> +}
> +
>  static struct drm_display_mode *
>  drm_connector_has_preferred_mode(struct drm_connector *connector, int width, int height)
>  {
> @@ -348,8 +362,17 @@ static bool drm_client_target_preferred(struct drm_connector **connectors,
>  	struct drm_connector *connector;
>  	u64 conn_configured = 0;
>  	int tile_pass = 0;
> +	int num_tiled_conns = 0;
>  	int i;
>  
> +	for (i = 0; i < connector_count; i++) {
> +		connector = connectors[i];
> +		if (!connector->has_tile)
> +			continue;
> +
> +		num_tiled_conns ++;
> +	}
> +
>  retry:
>  	for (i = 0; i < connector_count; i++) {
>  		connector = connectors[i];
> @@ -394,6 +417,12 @@ static bool drm_client_target_preferred(struct drm_connector **connectors,
>  				      connector->base.id, connector->tile_group ? connector->tile_group->id : 0);
>  			modes[i] = drm_connector_has_preferred_mode(connector, width, height);
>  		}
> +		if (connector->has_tile &&
> +		    num_tiled_conns < connector->num_h_tile * connector->num_v_tile) {
> +			DRM_DEBUG_KMS("Falling back to non tiled mode on Connector %d\n",
> +				      connector->base.id);
> +			modes[i] = drm_connector_fallback_non_tiled_mode(connector);
> +		}
>  		/* No preferred modes, pick one off the list */
>  		if (!modes[i] && !list_empty(&connector->modes)) {
>  			list_for_each_entry(modes[i], &connector->modes, head)
> -- 
> 2.19.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch