drm/i915: Add SIZE_HINTS property for cursors

Advertize more suitable cursor sizes via the new SIZE_HINTS
plane property.

We can't really enumerate all supported cursor sizes on
the platforms where the cursor height can vary freely, so
for simplicity we'll just expose all square+POT sizes between
each platform's min and max cursor limits.

Depending on the platform this will give us one of three
results:
- 64x64,128x128,256x256,512x512
- 64x64,128x128,256x256
- 64x64

Cc: Simon Ser <[e-mail]>
Cc: Jonas Ådahl <[e-mail]>
Cc: Daniel Stone <[e-mail]>
Cc: Sameer Lattannavar <[e-mail]>
Cc: Sebastian Wick <[e-mail]>
Cc: Harry Wentland <[e-mail]>
Cc: Pekka Paalanen <[e-mail]>
Signed-off-by: Ville Syrjälä <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Reviewed-by: Juha-Pekka Heikkila <[e-mail]>

drivers/gpu/drm/i915/display/intel_cursor.c

···
 	.format_mod_supported = intel_cursor_format_mod_supported,
 };
 
+static void intel_cursor_add_size_hints_property(struct intel_plane *plane)
+{
+	struct drm_i915_private *i915 = to_i915(plane->base.dev);
+	const struct drm_mode_config *config = &i915->drm.mode_config;
+	struct drm_plane_size_hint hints[4];
+	int size, max_size, num_hints = 0;
+
+	max_size = min(config->cursor_width, config->cursor_height);
+
+	/* for simplicity only enumerate the supported square+POT sizes */
+	for (size = 64; size <= max_size; size *= 2) {
+		if (drm_WARN_ON(&i915->drm, num_hints >= ARRAY_SIZE(hints)))
+			break;
+
+		hints[num_hints].width = size;
+		hints[num_hints].height = size;
+		num_hints++;
+	}
+
+	drm_plane_add_size_hints_property(&plane->base, hints, num_hints);
+}
+
 struct intel_plane *
 intel_cursor_plane_create(struct drm_i915_private *dev_priv,
 			  enum pipe pipe)
···
 						   DRM_MODE_ROTATE_0,
 						   DRM_MODE_ROTATE_0 |
 						   DRM_MODE_ROTATE_180);
+
+	intel_cursor_add_size_hints_property(cursor);
 
 	zpos = DISPLAY_RUNTIME_INFO(dev_priv)->num_sprites[pipe] + 1;
 	drm_plane_create_zpos_immutable_property(&cursor->base, zpos);