EXT_image_dma_buf_import_modifiers: Correct no-modifier-token behaviour
Zero is a valid and explicit modifier token, meaning that the image is
pitch-linear, i.e. no tiling or compression is applied.
When no modifier is passed for dmabuf import, the implementation may
assume the image is linear, but is not required to do so. Many drivers
which supported tiling formats before modifiers (or which do not yet
support modifiers) will determine the layout via other mechanisms, e.g.
metadata held by the kernel.
Fix the wording for the case where the user does not explicitly pass
modifiers to state that the layout will be determined by the
implementation, rather than stating the layout must be linear.
Reported by @olvaffe
diff --git a/extensions/EXT/EGL_EXT_image_dma_buf_import_modifiers.txt b/extensions/EXT/EGL_EXT_image_dma_buf_import_modifiers.txt
index 2b470c7..41b91c0 100644
--- a/extensions/EXT/EGL_EXT_image_dma_buf_import_modifiers.txt
+++ b/extensions/EXT/EGL_EXT_image_dma_buf_import_modifiers.txt
@@ -24,7 +24,7 @@
Version
- Version 4, October 20, 2016
+ Version 5, March 12, 2019
Number
@@ -111,8 +111,10 @@
attribute values may be given. These attribute values together form an
unsigned 64-bit value called a format modifier. Format modifiers are
specified by drm_fourcc.h and used as the modifier parameter of the
- drm_mode_fb_cmd2 ioctl. If neither of the two attributes are given, the
- format modifier is assumed to be zero. The two attributes are:
+ drm_mode_fb_cmd2 ioctl. If neither of the two attributes are given, or
+ if the modifier is explicitly declared to be DRM_FORMAT_MOD_INVALID, the
+ effective format modifier is implementation-defined. The two attributes
+ are:
* EGL_DMA_BUF_PLANE0_MODIFIER_LO_EXT: The lowest 32 bits of the
64-bit format modifier.
@@ -220,6 +222,10 @@
Revision History
+#5 (Daniel Stone, March 12, 2019)
+ - Correct description of behaviour when a modifier is not explicitly given;
+ zero is not correct as it is an explicit modifier itself (linear).
+
#4 (Daniel Stone, October 20, 2016)
- Switch to EGLuint64KHR for modifier types.
