docs/specs/EGL_MESA_drm_image_formats.txt

   1 Name
   2
   3     MESA_drm_image_formats
   4
   5 Name Strings
   6
   7     EGL_MESA_drm_image_formats
   8
   9 Contributors
  10
  11     Nicolai Hähnle <Nicolai.Haehnle@amd.com>
  12     Qiang Yu <Qiang.Yu@amd.com>
  13
  14 Contact
  15
  16     Nicolai Hähnle <Nicolai.Haehnle@amd.com>
  17
  18 Status
  19
  20     Proposal
  21
  22 Version
  23
  24     Version 1, January 26, 2017
  25
  26 Number
  27
  28     EGL Extension #??
  29
  30 Dependencies
  31
  32     This extension requires the EGL_MESA_drm_image extension.
  33
  34     This extension is written against the wording of EGL_MESA_drm_image
  35     specification.
  36
  37 Overview
  38
  39     This extension extends the functionality of EGL_MESA_drm_image by adding
  40     additional formats required by Glamor for use with DRM buffers.
  41
  42 IP Status
  43
  44     Open-source; freely implementable.
  45
  46 New Procedures and Functions
  47
  48     None
  49
  50 New Tokens
  51
  52     Accepted as values for the EGL_IMAGE_FORMAT_MESA attribute:
  53
  54         EGL_DRM_BUFFER_FORMAT_ARGB2101010_MESA  0x3290
  55         EGL_DRM_BUFFER_FORMAT_ARGB1555_MESA     0x3291
  56         EGL_DRM_BUFFER_FORMAT_RGB565_MESA       0x3292
  57
  58 Additions to the EGL_MESA_drm_image Specification:
  59
  60     Remove the sentence "The only format specified ..." from the paragraph
  61     describing eglCreateDRMImageMESA and add the following paragraph:
  62
  63         The formats specified for use with EGL_DRM_BUFFER_FORMAT_MESA are:
  64
  65       * EGL_DRM_BUFFER_FORMAT_ARGB32_MESA, where each pixel is a CPU-endian
  66         32-bit quantity, with alpha in the upper 8 bits, then red, then green,
  67         then blue,
  68
  69       * EGL_DRM_BUFFER_FORMAT_ARGB2101010_MESA, where each pixel is a CPU-
  70         endian, 32-bit quantity, with alpha in the most significant 2 bits,
  71         followed by 10 bits each for red, green, and blue,
  72
  73       * EGL_DRM_BUFFER_FORMAT_ARGB1555_MESA, where each pixel is a CPU-endian
  74         16-bit quantity, with alpha in the most significant bit, followed by
  75         5 bits each for red, green, and blue, and
  76
  77       * EGL_DRM_BUFFER_FORMAT_RGB565_MESA, where each pixel is a CPU-endian
  78         16-bit quantity, with red in the 5 most significant bits, followed by
  79         6 bits of green and 5 bits of blue.
  80
  81 Issues
  82
  83     1. Should we expose the full set of channel permutations for the formats,
  84        e.g. ABGR2101010, RGBA1010102, and BGRA1010102 in addition to
  85        ARGB2101010?
  86
  87        RESOLVED: No.
  88
  89        DISCUSSION: The original extension sets a precedent of only exposing one
  90        of the possible permutations of 8-bit channel formats. It is also not
  91        clear where the additional permutations would be used. For example,
  92        Glamor has a fixed mapping from pixmap/screen depth to format that
  93        doesn't allow for the other permutations.
  94
  95 Revision History
  96
  97     Version 1, January, 2017
  98         Initial draft (Nicolai Hähnle)