[Mesa-dev] [PATCH v3 2/3] mesa/st: enable EXT_sRGB_write_control for drivers that support it

[Gert Wollny]

From: Gert Wollny <gert.wollny at collabora.com>

With this patch the extension EXT_sRGB_write_control is enabled for
gallium drivers that support sRGB formats as render targets.

Tested (and pass) on r600 (evergreen) and softpipe:

  dEQP-GLES31.functional.fbo.srgb_write_control.framebuffer_srgb_enabled*

with "MESA_GLES_VERSION_OVERRIDE=3.2" (the tests needlessly check for this), and

  dEQP-GLES31.functional.fbo.srgb_write_control.framebuffer_srgb_unsupported_enum

when extension is manually disabled via MESA_EXTENSION_OVERRIDE

v2: - always enable the extension when sRGB is supported (Ilia Mirkin).
    - Correct handling by moving extension initialization to the
      place where gallium/st actually takes care of this. This also
      fixes properly disabling the extension via MESA_EXTENSION_OVERRIDE
    - reinstate check for desktop GL and add check for the extension
      when creating the framebuffer

v3: Only create sRGB renderbuffers based on Visual.srgbCapable when
    on desktop GL.

Signed-off-by: Gert Wollny <gert.wollny at collabora.com>
---
 src/mesa/state_tracker/st_extensions.c |  6 +++++
 src/mesa/state_tracker/st_manager.c    | 37 ++++++++++++++++----------
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/src/mesa/state_tracker/st_extensions.c b/src/mesa/state_tracker/st_extensions.c
index 798ee60875..401609d728 100644
--- a/src/mesa/state_tracker/st_extensions.c
+++ b/src/mesa/state_tracker/st_extensions.c
@@ -1169,6 +1169,12 @@ void st_init_extensions(struct pipe_screen *screen,
                                      void_formats, 32,
                                      PIPE_BIND_RENDER_TARGET);
 
+      extensions->EXT_sRGB_write_control =
+         screen->is_format_supported(screen, PIPE_FORMAT_R8G8B8A8_SRGB,
+                                     PIPE_TEXTURE_2D, 0, 0,
+                                     (PIPE_BIND_DISPLAY_TARGET |
+                                      PIPE_BIND_RENDER_TARGET));
+
       if (extensions->AMD_framebuffer_multisample_advanced) {
          /* AMD_framebuffer_multisample_advanced */
          /* This can be greater than storage samples. */
diff --git a/src/mesa/state_tracker/st_manager.c b/src/mesa/state_tracker/st_manager.c
index ceb48dd490..df898beb23 100644
--- a/src/mesa/state_tracker/st_manager.c
+++ b/src/mesa/state_tracker/st_manager.c
@@ -295,7 +295,7 @@ st_framebuffer_update_attachments(struct st_framebuffer *stfb)
  */
 static boolean
 st_framebuffer_add_renderbuffer(struct st_framebuffer *stfb,
-                                gl_buffer_index idx)
+                                gl_buffer_index idx, bool prefer_srgb)
 {
    struct gl_renderbuffer *rb;
    enum pipe_format format;
@@ -318,7 +318,7 @@ st_framebuffer_add_renderbuffer(struct st_framebuffer *stfb,
       break;
    default:
       format = stfb->iface->visual->color_format;
-      if (stfb->Base.Visual.sRGBCapable)
+      if (prefer_srgb)
          format = util_format_srgb(format);
       sw = FALSE;
       break;
@@ -436,6 +436,7 @@ st_framebuffer_create(struct st_context *st,
    struct st_framebuffer *stfb;
    struct gl_config mode;
    gl_buffer_index idx;
+   bool prefer_srgb = false;
 
    if (!stfbi)
       return NULL;
@@ -457,14 +458,15 @@ st_framebuffer_create(struct st_context *st,
     * format such that util_format_srgb(visual->color_format) can be supported
     * by the pipe driver.  We still need to advertise the capability here.
     *
-    * For GLES, however, sRGB framebuffer write is controlled only by the
-    * capability of the framebuffer.  There is GL_EXT_sRGB_write_control to
-    * give applications the control back, but sRGB write is still enabled by
-    * default.  To avoid unexpected results, we should not advertise the
-    * capability.  This could change when we add support for
-    * EGL_KHR_gl_colorspace.
+    * For GLES, however, sRGB framebuffer write is initially only controlled
+    * by the capability of the framebuffer, with GL_EXT_sRGB_write_control
+    * control is given back to the applications, but GL_FRAMEBUFFER_SRGB is
+    * still enabled by default since this is the behaviour when
+    * EXT_sRGB_write_control is not available.
     */
-   if (_mesa_is_desktop_gl(st->ctx)) {
+   if (_mesa_is_desktop_gl(st->ctx) ||
+       st->ctx->Extensions.EXT_sRGB_write_control)
+   {
       struct pipe_screen *screen = st->pipe->screen;
       const enum pipe_format srgb_format =
          util_format_srgb(stfbi->visual->color_format);
@@ -475,8 +477,14 @@ st_framebuffer_create(struct st_context *st,
                                       PIPE_TEXTURE_2D, stfbi->visual->samples,
                                       stfbi->visual->samples,
                                       (PIPE_BIND_DISPLAY_TARGET |
-                                       PIPE_BIND_RENDER_TARGET)))
+                                       PIPE_BIND_RENDER_TARGET))) {
          mode.sRGBCapable = GL_TRUE;
+         /* Since GL_FRAMEBUFFER_SRGB is enabled by default on GLES we must not
+          * create renderbuffers with an sRGB format derived from the
+          * visual->color_format, but we still want this for desktop GL.
+          */
+         prefer_srgb = _mesa_is_desktop_gl(st->ctx);
+      }
    }
 
    _mesa_initialize_window_framebuffer(&stfb->Base, &mode);
@@ -487,13 +495,13 @@ st_framebuffer_create(struct st_context *st,
 
    /* add the color buffer */
    idx = stfb->Base._ColorDrawBufferIndexes[0];
-   if (!st_framebuffer_add_renderbuffer(stfb, idx)) {
+   if (!st_framebuffer_add_renderbuffer(stfb, idx, prefer_srgb)) {
       free(stfb);
       return NULL;
    }
 
-   st_framebuffer_add_renderbuffer(stfb, BUFFER_DEPTH);
-   st_framebuffer_add_renderbuffer(stfb, BUFFER_ACCUM);
+   st_framebuffer_add_renderbuffer(stfb, BUFFER_DEPTH, false);
+   st_framebuffer_add_renderbuffer(stfb, BUFFER_ACCUM, false);
 
    stfb->stamp = 0;
    st_framebuffer_update_attachments(stfb);
@@ -1189,7 +1197,8 @@ st_manager_add_color_renderbuffer(struct st_context *st,
       return FALSE;
    }
 
-   if (!st_framebuffer_add_renderbuffer(stfb, idx))
+   if (!st_framebuffer_add_renderbuffer(stfb, idx,
+                                        stfb->Base.Visual.sRGBCapable))
       return FALSE;
 
    st_framebuffer_update_attachments(stfb);
-- 
2.18.1