drm: Define DRM_FORMAT_MAX_PLANES

DRM uses a magic number of 4 for the maximum number of planes per color
format. Declare this constant via DRM_FORMAT_MAX_PLANES and update the
related code. Some code depends on the length of arrays that are now
declared with DRM_FORMAT_MAX_PLANES. Convert it from '4' to ARRAY_SIZE.

v2:
	* mention usage of ARRAY_SIZE() in the commit message (Maxime)
	* also fix error handling in drm_gem_fb_init_with_funcs()
	  (kernel test robot)
	* include <drm/drm_fourcc.h> for DRM_FORMAT_MAX_PLANES

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210730183511.20080-2-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
index 67bc9ed..421e029 100644 (file)
--- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
+++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
@@ -48,7 +48,7 @@
 struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
                                          unsigned int plane)
 {
-       if (plane >= 4)
+       if (plane >= ARRAY_SIZE(fb->obj))
                return NULL;
 
        return fb->obj[plane];
@@ -62,7 +62,8 @@ drm_gem_fb_init(struct drm_device *dev,
                 struct drm_gem_object **obj, unsigned int num_planes,
                 const struct drm_framebuffer_funcs *funcs)
 {
-       int ret, i;
+       unsigned int i;
+       int ret;
 
        drm_helper_mode_fill_fb_struct(dev, fb, mode_cmd);
 
@@ -86,9 +87,9 @@ drm_gem_fb_init(struct drm_device *dev,
  */
 void drm_gem_fb_destroy(struct drm_framebuffer *fb)
 {
-       int i;
+       size_t i;
 
-       for (i = 0; i < 4; i++)
+       for (i = 0; i < ARRAY_SIZE(fb->obj); i++)
                drm_gem_object_put(fb->obj[i]);
 
        drm_framebuffer_cleanup(fb);
@@ -145,8 +146,9 @@ int drm_gem_fb_init_with_funcs(struct drm_device *dev,
                               const struct drm_framebuffer_funcs *funcs)
 {
        const struct drm_format_info *info;
-       struct drm_gem_object *objs[4];
-       int ret, i;
+       struct drm_gem_object *objs[DRM_FORMAT_MAX_PLANES];
+       unsigned int i;
+       int ret;
 
        info = drm_get_format_info(dev, mode_cmd);
        if (!info) {
@@ -187,9 +189,10 @@ int drm_gem_fb_init_with_funcs(struct drm_device *dev,
        return 0;
 
 err_gem_object_put:
-       for (i--; i >= 0; i--)
+       while (i > 0) {
+               --i;
                drm_gem_object_put(objs[i]);
-
+       }
        return ret;
 }
 EXPORT_SYMBOL_GPL(drm_gem_fb_init_with_funcs);

diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
index 3b138d4..22aa64d 100644 (file)
--- a/include/drm/drm_fourcc.h
+++ b/include/drm/drm_fourcc.h
@@ -25,6 +25,11 @@
 #include <linux/types.h>
 #include <uapi/drm/drm_fourcc.h>
 
+/**
+ * DRM_FORMAT_MAX_PLANES - maximum number of planes a DRM format can have
+ */
+#define DRM_FORMAT_MAX_PLANES  4u
+
 /*
  * DRM formats are little endian.  Define host endian variants for the
  * most common formats here, to reduce the #ifdefs needed in drivers.
@@ -78,7 +83,7 @@ struct drm_format_info {
                 * triplet @char_per_block, @block_w, @block_h for better
                 * describing the pixel format.
                 */
-               u8 cpp[4];
+               u8 cpp[DRM_FORMAT_MAX_PLANES];
 
                /**
                 * @char_per_block:
@@ -104,7 +109,7 @@ struct drm_format_info {
                 * information from their drm_mode_config.get_format_info hook
                 * if they want the core to be validating the pitch.
                 */
-               u8 char_per_block[4];
+               u8 char_per_block[DRM_FORMAT_MAX_PLANES];
        };
 
        /**
@@ -113,7 +118,7 @@ struct drm_format_info {
         * Block width in pixels, this is intended to be accessed through
         * drm_format_info_block_width()
         */
-       u8 block_w[4];
+       u8 block_w[DRM_FORMAT_MAX_PLANES];
 
        /**
         * @block_h:
@@ -121,7 +126,7 @@ struct drm_format_info {
         * Block height in pixels, this is intended to be accessed through
         * drm_format_info_block_height()
         */
-       u8 block_h[4];
+       u8 block_h[DRM_FORMAT_MAX_PLANES];
 
        /** @hsub: Horizontal chroma subsampling factor */
        u8 hsub;

diff --git a/include/drm/drm_framebuffer.h b/include/drm/drm_framebuffer.h
index be658eb..f67c5b7 100644 (file)
--- a/include/drm/drm_framebuffer.h
+++ b/include/drm/drm_framebuffer.h
@@ -27,12 +27,12 @@
 #include <linux/list.h>
 #include <linux/sched.h>
 
+#include <drm/drm_fourcc.h>
 #include <drm/drm_mode_object.h>
 
 struct drm_clip_rect;
 struct drm_device;
 struct drm_file;
-struct drm_format_info;
 struct drm_framebuffer;
 struct drm_gem_object;
 
@@ -147,7 +147,7 @@ struct drm_framebuffer {
         * @pitches: Line stride per buffer. For userspace created object this
         * is copied from drm_mode_fb_cmd2.
         */
-       unsigned int pitches[4];
+       unsigned int pitches[DRM_FORMAT_MAX_PLANES];
        /**
         * @offsets: Offset from buffer start to the actual pixel data in bytes,
         * per buffer. For userspace created object this is copied from
@@ -165,7 +165,7 @@ struct drm_framebuffer {
         * data (even for linear buffers). Specifying an x/y pixel offset is
         * instead done through the source rectangle in &struct drm_plane_state.
         */
-       unsigned int offsets[4];
+       unsigned int offsets[DRM_FORMAT_MAX_PLANES];
        /**
         * @modifier: Data layout modifier. This is used to describe
         * tiling, or also special layouts (like compression) of auxiliary
@@ -210,7 +210,7 @@ struct drm_framebuffer {
         * This is used by the GEM framebuffer helpers, see e.g.
         * drm_gem_fb_create().
         */
-       struct drm_gem_object *obj[4];
+       struct drm_gem_object *obj[DRM_FORMAT_MAX_PLANES];
 };
 
 #define obj_to_fb(x) container_of(x, struct drm_framebuffer, base)

diff --git a/include/drm/drm_gem_atomic_helper.h b/include/drm/drm_gem_atomic_helper.h
index d82c236..f9f8b6f 100644 (file)
--- a/include/drm/drm_gem_atomic_helper.h
+++ b/include/drm/drm_gem_atomic_helper.h
@@ -5,6 +5,7 @@
 
 #include <linux/dma-buf-map.h>
 
+#include <drm/drm_fourcc.h>
 #include <drm/drm_plane.h>
 
 struct drm_simple_display_pipe;
@@ -40,7 +41,7 @@ struct drm_shadow_plane_state {
         * The memory mappings stored in map should be established in the plane's
         * prepare_fb callback and removed in the cleanup_fb callback.
         */
-       struct dma_buf_map map[4];
+       struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
 };
 
 /**