glamor_egl: Don't initialize on llvmpipe

Mesa started supporting GL_OES_EGL_image on llvmpipe in 17.3, after this
commit:

    commit bbdeddd5fd0b797e1e281f058338b3da4d98029d
    Author: Gurchetan Singh <gurchetansingh@chromium.org>
    Date:   Tue Aug 1 14:49:33 2017 -0700

        st/dri: add drisw image extension

That's pretty cool, but it means glamor now thinks it can initialize on
llvmpipe. This is almost certainly not what anyone wants, as glamor on
llvmpipe is pretty much uniformly slower than fb.

This fixes both Xorg and Xwayland to refuse glamor in such a setup.
Xephyr is left alone, both because glamor is not the default there and
because Xephyr+glamor+llvmpipe is one of the easier ways to get xts to
exercise glamor.

The (very small) downside of this change is that you lose DRI3 support.
This wouldn't have helped you very much (since an lp glamor blit is
slower than a pixman blit), but it would eliminate the PutImage overhead
for llvmpipe's glXSwapBuffers. A future change should add DRI3 support
for the fb-only case.

Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Adam Jackson <ajax@redhat.com>

2 files changed, 15 insertions, 1 deletions

diff --git a/glamor/glamor_egl.c b/glamor/glamor_egl.c
index df278b1a1..9b930d603 100644
--- a/glamor/glamor_egl.c
+++ b/glamor/glamor_egl.c
@@ -898,6 +898,7 @@ Bool
 glamor_egl_init(ScrnInfoPtr scrn, int fd)
 {
     struct glamor_egl_screen_private *glamor_egl;
+    const GLubyte *renderer;
 
     glamor_egl = calloc(sizeof(*glamor_egl), 1);
     if (glamor_egl == NULL)
@@ -992,6 +993,14 @@ glamor_egl_init(ScrnInfoPtr scrn, int fd)
                    "Failed to make EGL context current\n");
         goto error;
     }
+
+    renderer = glGetString(GL_RENDERER);
+    if (strstr((const char *)renderer, "llvmpipe")) {
+        xf86DrvMsg(scrn->scrnIndex, X_INFO,
+                   "Refusing to try glamor on llvmpipe\n");
+        goto error;
+    }
+
     /*
      * Force the next glamor_make_current call to set the right context
      * (in case of multiple GPUs using glamor)
@@ -1005,7 +1014,7 @@ glamor_egl_init(ScrnInfoPtr scrn, int fd)
     }
 
     xf86DrvMsg(scrn->scrnIndex, X_INFO, "glamor X acceleration enabled on %s\n",
-               glGetString(GL_RENDERER));
+               renderer);
 
 #ifdef GBM_BO_WITH_MODIFIERS
     if (epoxy_has_egl_extension(glamor_egl->display,
diff --git a/hw/xwayland/xwayland-glamor-gbm.c b/hw/xwayland/xwayland-glamor-gbm.c
index 06fcf5239..25a354bf7 100644
--- a/hw/xwayland/xwayland-glamor-gbm.c
+++ b/hw/xwayland/xwayland-glamor-gbm.c
@@ -843,6 +843,11 @@ xwl_glamor_gbm_init_egl(struct xwl_screen *xwl_screen)
         goto error;
     }
 
+    if (strstr((const char *)glGetString(GL_RENDERER), "llvmpipe")) {
+        ErrorF("Refusing to try glamor on llvmpipe\n");
+        goto error;
+    }
+
     if (!epoxy_has_gl_extension("GL_OES_EGL_image")) {
         ErrorF("GL_OES_EGL_image not available\n");
         goto error;