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Name
MESA_drm_image_formats
Name Strings
EGL_MESA_drm_image_formats
Contributors
Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Qiang Yu <Qiang.Yu@amd.com>
Contact
Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Status
Proposal
Version
Version 1, January 26, 2017
Number
EGL Extension #??
Dependencies
This extension requires the EGL_MESA_drm_image extension.
This extension is written against the wording of EGL_MESA_drm_image
specification.
Overview
This extension extends the functionality of EGL_MESA_drm_image by adding
additional formats required by Glamor for use with DRM buffers.
IP Status
Open-source; freely implementable.
New Procedures and Functions
None
New Tokens
Accepted as values for the EGL_IMAGE_FORMAT_MESA attribute:
EGL_DRM_BUFFER_FORMAT_ARGB2101010_MESA 0x3290
EGL_DRM_BUFFER_FORMAT_ARGB1555_MESA 0x3291
EGL_DRM_BUFFER_FORMAT_RGB565_MESA 0x3292
Additions to the EGL_MESA_drm_image Specification:
Remove the sentence "The only format specified ..." from the paragraph
describing eglCreateDRMImageMESA and add the following paragraph:
The formats specified for use with EGL_DRM_BUFFER_FORMAT_MESA are:
* EGL_DRM_BUFFER_FORMAT_ARGB32_MESA, where each pixel is a CPU-endian
32-bit quantity, with alpha in the upper 8 bits, then red, then green,
then blue,
* EGL_DRM_BUFFER_FORMAT_ARGB2101010_MESA, where each pixel is a CPU-
endian, 32-bit quantity, with alpha in the most significant 2 bits,
followed by 10 bits each for red, green, and blue,
* EGL_DRM_BUFFER_FORMAT_ARGB1555_MESA, where each pixel is a CPU-endian
16-bit quantity, with alpha in the most significant bit, followed by
5 bits each for red, green, and blue, and
* EGL_DRM_BUFFER_FORMAT_RGB565_MESA, where each pixel is a CPU-endian
16-bit quantity, with red in the 5 most significant bits, followed by
6 bits of green and 5 bits of blue.
Issues
1. Should we expose the full set of channel permutations for the formats,
e.g. ABGR2101010, RGBA1010102, and BGRA1010102 in addition to
ARGB2101010?
RESOLVED: No.
DISCUSSION: The original extension sets a precedent of only exposing one
of the possible permutations of 8-bit channel formats. It is also not
clear where the additional permutations would be used. For example,
Glamor has a fixed mapping from pixmap/screen depth to format that
doesn't allow for the other permutations.
Revision History
Version 1, January, 2017
Initial draft (Nicolai Hähnle)
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