From caf99133ece234607a180dc4191ff68f30a8baf1 Mon Sep 17 00:00:00 2001
From: Dave Airlie <airlied@redhat.com>
Date: Tue, 20 Feb 2024 13:10:29 +1000
Subject: [PATCH] glx/dri3: handle zink fallback if loader picks it.

if we get a zink driver selected for the fd then don't bind it to dri3
return a special error and this should stop dri2 binding it.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27628>
---
 src/glx/dri3_glx.c  | 11 +++++++++--
 src/glx/glxclient.h |  2 ++
 src/glx/glxext.c    |  8 ++++++--
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/glx/dri3_glx.c b/src/glx/dri3_glx.c
index a1c9fb56696..12a05246af1 100644
--- a/src/glx/dri3_glx.c
+++ b/src/glx/dri3_glx.c
@@ -800,6 +800,7 @@ dri3_create_screen(int screen, struct glx_display * priv)
    __GLXDRIscreen *psp;
    struct glx_config *configs = NULL, *visuals = NULL;
    char *driverName, *driverNameDisplayGPU, *tmp;
+   bool return_zink = false;
 
    psc = calloc(1, sizeof *psc);
    if (psc == NULL)
@@ -835,6 +836,11 @@ dri3_create_screen(int screen, struct glx_display * priv)
       goto handle_error;
    }
 
+   if (!strcmp(driverName, "zink")) {
+      return_zink = true;
+      goto handle_error;
+   }
+
    extensions = driOpenDriver(driverName, &psc->driver);
    if (extensions == NULL)
       goto handle_error;
@@ -1009,7 +1015,8 @@ dri3_create_screen(int screen, struct glx_display * priv)
    return &psc->base;
 
 handle_error:
-   CriticalErrorMessageF("failed to load driver: %s\n", driverName ? driverName : "(null)");
+   if (!return_zink)
+      CriticalErrorMessageF("failed to load driver: %s\n", driverName ? driverName : "(null)");
 
    if (configs)
        glx_config_destroy_list(configs);
@@ -1032,7 +1039,7 @@ handle_error:
    glx_screen_cleanup(&psc->base);
    free(psc);
 
-   return NULL;
+   return return_zink ? GLX_LOADER_USE_ZINK : NULL;
 }
 
 /** dri_destroy_display
diff --git a/src/glx/glxclient.h b/src/glx/glxclient.h
index 38980d76ddf..e262b4a80fa 100644
--- a/src/glx/glxclient.h
+++ b/src/glx/glxclient.h
@@ -78,6 +78,8 @@ typedef struct __GLXDRIdisplayRec __GLXDRIdisplay;
 typedef struct __GLXDRIscreenRec __GLXDRIscreen;
 typedef struct __GLXDRIdrawableRec __GLXDRIdrawable;
 
+#define GLX_LOADER_USE_ZINK ((struct glx_screen *)(uintptr_t)-1)
+
 struct __GLXDRIdisplayRec
 {
     /**
diff --git a/src/glx/glxext.c b/src/glx/glxext.c
index 05c825a2b07..6cf04d1b745 100644
--- a/src/glx/glxext.c
+++ b/src/glx/glxext.c
@@ -794,7 +794,7 @@ AllocAndFetchScreenConfigs(Display * dpy, struct glx_display * priv, Bool zink)
 	 psc = priv->windowsdriDisplay->createScreen(i, priv);
 #endif
 
-      if (psc == NULL && priv->driswDisplay)
+      if ((psc == GLX_LOADER_USE_ZINK || psc == NULL) && priv->driswDisplay)
 	 psc = priv->driswDisplay->createScreen(i, priv);
 #endif /* GLX_DIRECT_RENDERING && !GLX_USE_APPLEGL */
 
@@ -903,8 +903,12 @@ __glXInitialize(Display * dpy)
 #if defined(GLX_USE_DRM)
    if (glx_direct && glx_accel && !zink) {
 #if defined(HAVE_DRI3)
-      if (!debug_get_bool_option("LIBGL_DRI3_DISABLE", false))
+      if (!debug_get_bool_option("LIBGL_DRI3_DISABLE", false)) {
          dpyPriv->dri3Display = dri3_create_display(dpy);
+         /* nouveau wants to fallback to zink so if we get a screen enable try_zink */
+         if (dpyPriv->dri3Display)
+            try_zink = !debug_get_bool_option("LIBGL_KOPPER_DISABLE", false);
+      }
 #endif /* HAVE_DRI3 */
       if (!debug_get_bool_option("LIBGL_DRI2_DISABLE", false))
          dpyPriv->dri2Display = dri2CreateDisplay(dpy);