[RFC PATCH v5 2/3] drm: add support modifiers for drivers whose planes only support linear layout

[Tomohito Esaki]

The LINEAR modifier is advertised as default if a driver doesn't specify
modifiers.

Signed-off-by: Tomohito Esaki <e...@igel.co.jp>
---
 drivers/gpu/drm/drm_plane.c | 23 +++++++++++++----------
 include/drm/drm_plane.h     |  3 +++
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index deeec60a3315..bf0daa8d9bbd 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -237,6 +237,9 @@ static int __drm_universal_plane_init(struct drm_device 
*dev,
                                      const char *name, va_list ap)
 {
        struct drm_mode_config *config = &dev->mode_config;
+       static const uint64_t default_modifiers[] = {
+               DRM_FORMAT_MOD_LINEAR,
+       };
        unsigned int format_modifier_count = 0;
        int ret;
 
@@ -277,16 +280,16 @@ static int __drm_universal_plane_init(struct drm_device 
*dev,
 
                while (*temp_modifiers++ != DRM_FORMAT_MOD_INVALID)
                        format_modifier_count++;
+       } else {
+               if (!dev->mode_config.fb_modifiers_not_supported) {
+                       format_modifiers = default_modifiers;
+                       format_modifier_count = ARRAY_SIZE(default_modifiers);
+               }
        }
 
        /* autoset the cap and check for consistency across all planes */
-       if (format_modifier_count) {
-               drm_WARN_ON(dev, !config->allow_fb_modifiers &&
-                           !list_empty(&config->plane_list));
-               config->allow_fb_modifiers = true;
-       } else {
-               drm_WARN_ON(dev, config->allow_fb_modifiers);
-       }
+       drm_WARN_ON(dev, config->fb_modifiers_not_supported &&
+                               format_modifier_count);
 
        plane->modifier_count = format_modifier_count;
        plane->modifiers = kmalloc_array(format_modifier_count,
@@ -341,7 +344,7 @@ static int __drm_universal_plane_init(struct drm_device 
*dev,
                drm_object_attach_property(&plane->base, config->prop_src_h, 0);
        }
 
-       if (config->allow_fb_modifiers)
+       if (format_modifier_count)
                create_in_format_blob(dev, plane);
 
        return 0;
@@ -368,8 +371,8 @@ static int __drm_universal_plane_init(struct drm_device 
*dev,
  * drm_universal_plane_init() to let the DRM managed resource infrastructure
  * take care of cleanup and deallocation.
  *
- * Drivers supporting modifiers must set @format_modifiers on all their planes,
- * even those that only support DRM_FORMAT_MOD_LINEAR.
+ * Drivers that only support the DRM_FORMAT_MOD_LINEAR modifier support may set
+ * @format_modifiers to NULL. The plane will advertise the linear modifier.
  *
  * Returns:
  * Zero on success, error code on failure.
diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
index 0c1102dc4d88..a0390b6ad3b4 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -803,6 +803,9 @@ void *__drmm_universal_plane_alloc(struct drm_device *dev,
  *
  * The @drm_plane_funcs.destroy hook must be NULL.
  *
+ * Drivers that only support the DRM_FORMAT_MOD_LINEAR modifier support may set
+ * @format_modifiers to NULL. The plane will advertise the linear modifier.
+ *
  * Returns:
  * Pointer to new plane, or ERR_PTR on failure.
  */
-- 
2.25.1