[Mesa-dev] [PATCH 1/2] egl: Support IMG_context_priority

[Ben Widawsky]

On 17-04-06 20:12:35, Chris Wilson wrote:
>IMG_context_priority
>https://www.khronos.org/registry/egl/extensions/IMG/EGL_IMG_context_priority.txt
>
>    "This extension allows an EGLContext to be created with a priority
>    hint. It is possible that an implementation will not honour the
>    hint, especially if there are constraints on the number of high
>    priority contexts available in the system, or system policy limits
>    access to high priority contexts to appropriate system privilege
>    level. A query is provided to find the real priority level assigned
>    to the context after creation."
>
>The extension adds a new eglCreateContext attribute for choosing a
>priority hint. This stub parses the attribute and copies into the base
>struct _egl_context, and hooks up the query similarly.
>
>Since the attribute is purely a hint, I have no qualms about the lack of
>implementation before reporting back the value the user gave!
>
>Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>Reviewed-by: Tapani Pälli <tapani.palli at intel.com>
>Cc: Rob Clark <robdclark at gmail.com>
>---
> src/egl/drivers/dri2/egl_dri2.c |  1 +
> src/egl/main/eglapi.c           |  2 ++
> src/egl/main/eglcontext.c       | 30 ++++++++++++++++++++++++++++++
> src/egl/main/eglcontext.h       |  1 +
> src/egl/main/egldisplay.h       |  2 ++
> 5 files changed, 36 insertions(+)
>
>diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
>index 2cab7d00c1..60e1472ac1 100644
>--- a/src/egl/drivers/dri2/egl_dri2.c
>+++ b/src/egl/drivers/dri2/egl_dri2.c
>@@ -662,6 +662,7 @@ dri2_setup_screen(_EGLDisplay *disp)
>    assert(dri2_dpy->image_driver || dri2_dpy->dri2 || dri2_dpy->swrast);
>    disp->Extensions.KHR_no_config_context = EGL_TRUE;
>    disp->Extensions.KHR_surfaceless_context = EGL_TRUE;
>+   disp->Extensions.IMG_context_priority = EGL_TRUE; /* only a hint */
>
>    if (dri2_renderer_query_integer(dri2_dpy,
>                                    __DRI2_RENDERER_HAS_FRAMEBUFFER_SRGB))
>diff --git a/src/egl/main/eglapi.c b/src/egl/main/eglapi.c
>index 5694b5a4ca..9ed65b1bba 100644
>--- a/src/egl/main/eglapi.c
>+++ b/src/egl/main/eglapi.c
>@@ -490,6 +490,8 @@ _eglCreateExtensionsString(_EGLDisplay *dpy)
>    _EGL_CHECK_EXTENSION(EXT_image_dma_buf_import);
>    _EGL_CHECK_EXTENSION(EXT_swap_buffers_with_damage);
>
>+   _EGL_CHECK_EXTENSION(IMG_context_priority);
>+
>    _EGL_CHECK_EXTENSION(KHR_cl_event2);
>    _EGL_CHECK_EXTENSION(KHR_config_attribs);
>    _EGL_CHECK_EXTENSION(KHR_create_context);
>diff --git a/src/egl/main/eglcontext.c b/src/egl/main/eglcontext.c
>index 05cc523c8d..54151d6b24 100644
>--- a/src/egl/main/eglcontext.c
>+++ b/src/egl/main/eglcontext.c
>@@ -312,6 +312,33 @@ _eglParseContextAttribList(_EGLContext *ctx, _EGLDisplay *dpy,
>             ctx->Flags |= EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR;
>          break;
>
>+      case EGL_CONTEXT_PRIORITY_LEVEL_IMG:
>+         /* The  EGL_IMG_context_priority spec says:
>+          *
>+          * "EGL_CONTEXT_PRIORITY_LEVEL_IMG determines the priority level of
>+          * the context to be created. This attribute is a hint, as an
>+          * implementation may not support multiple contexts at some
>+          * priority levels and system policy may limit access to high
>+          * priority contexts to appropriate system privilege level. The
>+          * default value for EGL_CONTEXT_PRIORITY_LEVEL_IMG is
>+          * EGL_CONTEXT_PRIORITY_MEDIUM_IMG."
>+          */
>+         if (!dpy->Extensions.IMG_context_priority) {
>+            err = EGL_BAD_ATTRIBUTE;
>+            break;
>+         }
>+         switch (val) {
>+         case EGL_CONTEXT_PRIORITY_HIGH_IMG:
>+         case EGL_CONTEXT_PRIORITY_MEDIUM_IMG:
>+         case EGL_CONTEXT_PRIORITY_LOW_IMG:
>+            ctx->ContextPriority = val;
>+            break;
>+         default:
>+            err = EGL_BAD_ATTRIBUTE;
>+            break;
>+         }
>+         break;
>+
>       default:
>          err = EGL_BAD_ATTRIBUTE;
>          break;
>@@ -570,6 +597,9 @@ _eglQueryContext(_EGLDriver *drv, _EGLDisplay *dpy, _EGLContext *c,
>    case EGL_RENDER_BUFFER:
>       *value = _eglQueryContextRenderBuffer(c);
>       break;
>+   case EGL_CONTEXT_PRIORITY_LEVEL_IMG:
>+      *value = c->ContextPriority;
>+      break;
>    default:
>       return _eglError(EGL_BAD_ATTRIBUTE, "eglQueryContext");
>    }
>diff --git a/src/egl/main/eglcontext.h b/src/egl/main/eglcontext.h
>index f2fe806626..e8c2d7d4f3 100644
>--- a/src/egl/main/eglcontext.h
>+++ b/src/egl/main/eglcontext.h
>@@ -62,6 +62,7 @@ struct _egl_context
>    EGLint Flags;
>    EGLint Profile;
>    EGLint ResetNotificationStrategy;
>+   EGLint ContextPriority;

Should this be initialized to EGL_CONTEXT_PRIORITY_MEDIUM_IMG? Quick glance
through the spec doesn't make this immediately obvious, but it seems like yes to
me.

>
>    /* The real render buffer when a window surface is bound */
>    EGLint WindowRenderBuffer;
>diff --git a/src/egl/main/egldisplay.h b/src/egl/main/egldisplay.h
>index 6c1049d23c..84899ddcd0 100644
>--- a/src/egl/main/egldisplay.h
>+++ b/src/egl/main/egldisplay.h
>@@ -104,6 +104,8 @@ struct _egl_extensions
>    EGLBoolean EXT_image_dma_buf_import;
>    EGLBoolean EXT_swap_buffers_with_damage;
>
>+   EGLBoolean IMG_context_priority;
>+
>    EGLBoolean KHR_cl_event2;
>    EGLBoolean KHR_config_attribs;
>    EGLBoolean KHR_create_context;
>-- 
>2.11.0
>