egl: Support IMG_context_priority

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!

v2: Remember to set the default ContextPriority value to medium.
v3: Use the driRendererQuery interface to probe the backend for
supported priority values and use those to mask the EGL interface.
v4: Treat the priority attrib as a hint and gracefully mask any requests
not supported by the driver, the EGLContext will remain at medium
priority.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Emil Velikov <emli.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/include/GL/internal/dri_interface.h b/include/GL/internal/dri_interface.h
index aefba92c024ee55b1cdb7705b9da497bf04bd8c7..7ed0169a98459951a45e5cf698b34bcd46fb4988 100644 (file)
--- a/include/GL/internal/dri_interface.h
+++ b/include/GL/internal/dri_interface.h
@@ -1782,6 +1782,14 @@ typedef struct __DRIDriverVtableExtensionRec {
  */
 #define __DRI2_RENDERER_HAS_FRAMEBUFFER_SRGB                  0x000c
 
+/* Bitmaks of supported/available context priorities - must match
+ * __EGL_CONTEXT_PRIORITY_LOW_BIT et al
+ */
+#define __DRI2_RENDERER_HAS_CONTEXT_PRIORITY                  0x000d
+#define   __DRI2_RENDERER_HAS_CONTEXT_PRIORITY_LOW            (1 << 0)
+#define   __DRI2_RENDERER_HAS_CONTEXT_PRIORITY_MEDIUM         (1 << 1)
+#define   __DRI2_RENDERER_HAS_CONTEXT_PRIORITY_HIGH           (1 << 2)
+
 typedef struct __DRI2rendererQueryExtensionRec __DRI2rendererQueryExtension;
 struct __DRI2rendererQueryExtensionRec {
    __DRIextension base;

diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
index d7a88b2984483f4d0c697303af73368f3f2e986f..e18e05e4a99d45e0ba5ecc35bc172199ea22a739 100644 (file)
--- a/src/egl/drivers/dri2/egl_dri2.c
+++ b/src/egl/drivers/dri2/egl_dri2.c
@@ -687,6 +687,11 @@ dri2_setup_screen(_EGLDisplay *disp)
    disp->Extensions.KHR_no_config_context = EGL_TRUE;
    disp->Extensions.KHR_surfaceless_context = EGL_TRUE;
 
+   /* Report back to EGL the bitmask of priorities supported */
+   disp->Extensions.IMG_context_priority =
+      dri2_renderer_query_integer(dri2_dpy,
+                                  __DRI2_RENDERER_HAS_CONTEXT_PRIORITY);
+
    if (dri2_renderer_query_integer(dri2_dpy,
                                    __DRI2_RENDERER_HAS_FRAMEBUFFER_SRGB))
       disp->Extensions.KHR_gl_colorspace = EGL_TRUE;

diff --git a/src/egl/main/eglapi.c b/src/egl/main/eglapi.c
index 38fc9311cb8da3ed5f6f7a53ed91f011562fc498..215332f99cbb9a600829c7e862bb57554e0c6f40 100644 (file)
--- 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_modifiers);
    _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 1b03160439ae08491c191ed4b9e46ae9878ff65f..8c64f9ab82e8dbe1f898b09330afa34508f7e3ff 100644 (file)
--- a/src/egl/main/eglcontext.c
+++ b/src/egl/main/eglcontext.c
@@ -332,6 +332,60 @@ _eglParseContextAttribList(_EGLContext *ctx, _EGLDisplay *dpy,
          ctx->NoError = !!val;
          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."
+          */
+         {
+            int bit;
+
+            switch (val) {
+            case EGL_CONTEXT_PRIORITY_HIGH_IMG:
+               bit = __EGL_CONTEXT_PRIORITY_HIGH_BIT;
+               break;
+            case EGL_CONTEXT_PRIORITY_MEDIUM_IMG:
+               bit = __EGL_CONTEXT_PRIORITY_MEDIUM_BIT;
+               break;
+            case EGL_CONTEXT_PRIORITY_LOW_IMG:
+               bit = __EGL_CONTEXT_PRIORITY_LOW_BIT;
+               break;
+            default:
+               bit = -1;
+               break;
+            }
+
+            if (bit < 0) {
+               err = EGL_BAD_ATTRIBUTE;
+               break;
+            }
+
+            /* "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."
+             *
+             * We currently assume that the driver applies the priority hint
+             * and filters out any it cannot handle during the screen setup,
+             * e.g. dri2_setup_screen(). As such we can mask any change that
+             * the driver would fail, and ctx->ContextPriority matches the
+             * hint applied to the driver/hardware backend.
+             */
+            if (dpy->Extensions.IMG_context_priority & (1 << bit))
+               ctx->ContextPriority = val;
+
+            break;
+         }
+
       default:
          err = EGL_BAD_ATTRIBUTE;
          break;
@@ -533,6 +587,7 @@ _eglInitContext(_EGLContext *ctx, _EGLDisplay *dpy, _EGLConfig *conf,
    ctx->Flags = 0;
    ctx->Profile = EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR;
    ctx->ResetNotificationStrategy = EGL_NO_RESET_NOTIFICATION_KHR;
+   ctx->ContextPriority = EGL_CONTEXT_PRIORITY_MEDIUM_IMG;
 
    err = _eglParseContextAttribList(ctx, dpy, attrib_list);
    if (err == EGL_SUCCESS && ctx->Config) {
@@ -598,6 +653,9 @@ _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 0667622ba15f8656880fa9eb336ce874631dacf0..a75236831360a181558b4b4378d8c2b2f46e5090 100644 (file)
--- 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;
    EGLBoolean NoError;
 
    /* The real render buffer when a window surface is bound */

diff --git a/src/egl/main/egldisplay.h b/src/egl/main/egldisplay.h
index da5339b7bf9ebf9f57bf14776ecb3487d8899ace..952bfe53f00d50c8a770dae709b0c7d628ade4d9 100644 (file)
--- a/src/egl/main/egldisplay.h
+++ b/src/egl/main/egldisplay.h
@@ -105,6 +105,11 @@ struct _egl_extensions
    EGLBoolean EXT_image_dma_buf_import_modifiers;
    EGLBoolean EXT_swap_buffers_with_damage;
 
+   unsigned int IMG_context_priority;
+#define  __EGL_CONTEXT_PRIORITY_LOW_BIT    0
+#define  __EGL_CONTEXT_PRIORITY_MEDIUM_BIT 1
+#define  __EGL_CONTEXT_PRIORITY_HIGH_BIT   2
+
    EGLBoolean KHR_cl_event2;
    EGLBoolean KHR_config_attribs;
    EGLBoolean KHR_create_context;