kc3-lang/angle/extensions/EGL_ANGLE_power_preference.txt

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  Commit

• Author : Kenneth Russell
  Date : 2020-06-10 21:55:43
  Hash : af727792
  Message : Improve EGL_ANGLE_power_preference on dual-GPU MacBook Pros. Add the ability to release and reacquire the high-power GPU, and to respond to changes in the active GPU. In Chromium, the GPU process can not access the WindowServer. An external process must inform ANGLE that the active GPU has changed, and that ANGLE should switch its internal context to the new GPU. Incorporates a couple of functions from WebKit, used with permission, to effect this GPU switch. A follow-on change in Chromium which uses these new APIs will make the existing dual-GPU tests pass with ANGLE and the passthrough command decoder. Carry forward Chromium's workaround of disabling GPU switching on older MacBook Pros to ensure stability. Document the process of adding new EGL extensions to ANGLE. Bug: chromium:1091824 Change-Id: I499739156e851b493555d4d6e4aef87d8b97fa31 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2240638 Commit-Queue: Kenneth Russell <kbr@chromium.org> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com> Reviewed-by: Geoff Lang <geofflang@chromium.org>

• extensions/EGL_ANGLE_power_preference.txt

• Name
  
      ANGLE_power_preference
  
  Name Strings
  
      EGL_ANGLE_power_preference
  
  Contributors
  
      Kenneth Russell
  
  Contacts
  
      Kenneth Russell, Google Inc. (kbr 'at' google.com)
  
  Status
  
      Draft
  
  Version
  
      Version 1, April 16, 2019
  
  Number
  
      EGL Extension #??
  
  Dependencies
  
      This extension is written against the wording of the EGL 1.4
      Specification.
  
  Overview
  
      This extension allows selection of the high- or low-power GPU on
      dual-GPU systems, specifically on macOS.
  
  New Types
  
      None
  
  New Procedures and Functions
  
      void eglReleaseHighPowerGPUANGLE(
          EGLDisplay dpy,
          EGLContext context);
      void eglReacquireHighPowerGPUANGLE(
          EGLDisplay dpy,
          EGLContext context);
      void eglHandleGPUSwitchANGLE(EGLDisplay dpy);
  
  New Tokens
  
      Accepted as an attribute name in the <*attrib_list> argument to
      eglCreateContext:
  
          EGL_POWER_PREFERENCE_ANGLE  0x3482
  
      Accepted as an attribute value in the <*attrib_list> argument to
      eglCreateContext:
  
          EGL_LOW_POWER_ANGLE         0x0001
          EGL_HIGH_POWER_ANGLE        0x0002
  
  Additions to the EGL 1.4 Specification
  
      Add the following to section 3.7.1 "Creating Rendering Contexts":
  
      EGL_POWER_PREFERENCE_ANGLE indicates whether the context should be
      created on the integrated (low-power) or discrete (high-power) GPU
      on dual-GPU systems. EGL_POWER_PREFERENCE_ANGLE is only a legal
      context creation attribute when the EGL_ANGLE_power_preference
      extension is advertised. The valid values for this attribute are
      EGL_LOW_POWER_ANGLE and EGL_HIGH_POWER_ANGLE. If this extension is
      advertised and this context creation attribute is not specified,
      the default value is EGL_LOW_POWER_ANGLE.
  
      The containing application must set the
      NSSupportsAutomaticGraphicsSwitching attribute to true in its
      Info.plist in order for this extension to operate as advertised.
  
      eglReleaseHighPowerGPUANGLE, when passed an EGLContext allocated
      with the EGL_POWER_PREFERENCE_ANGLE context creation attribute set
      to EGL_HIGH_POWER_ANGLE, will cause that context to release its
      hold on the high-power GPU.
  
      eglReacquireHighPowerGPUANGLE, when passed an EGLContext allocated
      with the EGL_POWER_PREFERENCE_ANGLE context creation attribute set
      to EGL_HIGH_POWER_ANGLE and which was previously released via
      eglReleaseHighPowerGPUANGLE, will cause that context to reacquire
      its hold on the high-power GPU.
  
      eglReleaseHighPowerGPUANGLE and eglReacquireHighPowerGPUANGLE have
      no effect on contexts that were allocated with the
      EGL_LOW_POWER_ANGLE preference, or contexts not allocated with
      either preference.
  
      For either eglReleaseHighPowerGPUANGLE or
      eglReacquireHighPowerGPUANGLE:
  
      If |dpy| is not a valid display, an EGL_BAD_DISPLAY error is
      generated.
  
      if |dpy| is an uninitialized display, an EGL_NOT_INITIALIZED error
      is generated.
  
      If |context| is not a valid context, an EGL_BAD_CONTEXT error is
      generated.
  
      eglHandleGPUSwitchANGLE should be called in response to a display
      reconfiguration callback (registered via
      CGDisplayRegisterReconfigurationCallback) in order to complete
      transitions between the low-power and high-power GPUs. For calls
      to this function:
  
      If |dpy| is not a valid display, an EGL_BAD_DISPLAY error is
      generated.
  
      if |dpy| is an uninitialized display, an EGL_NOT_INITIALIZED error
      is generated.
  
  Issues
  
      None yet.
  
  Revision History
  
      Rev.    Date         Author     Changes
      ----  -------------  ---------  ----------------------------------------
        1   Apr 16, 2019   kbr        Initial version
        2   June 5, 2020   kbr        Add eglReleaseHighPowerGPUANGLE,
                                        eglReacquireHighPowerGPUANGLE, and
                                        eglHandleGPUSwitchANGLE