gl-renderer: improve get_egl_config errors

Listing exactly what we were looking for but did not find should help debugging
failures.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

diff --git a/libweston/renderer-gl/egl-glue.c b/libweston/renderer-gl/egl-glue.c
index 2c44c86bcf39712befa3503e17ba41b293478364..b238d6a9f0d9b74a297fc33592fb0ed0292f39ae 100644 (file)
--- a/libweston/renderer-gl/egl-glue.c
+++ b/libweston/renderer-gl/egl-glue.c
@@ -75,6 +75,31 @@ gl_renderer_print_egl_error_state(void)
                egl_error_string(code), (long)code);
 }
 
+static void
+print_egl_surface_type_bits(FILE *fp, EGLint egl_surface_type)
+{
+       const char *sep = "";
+       unsigned i;
+
+       static const struct {
+               EGLint bit;
+               const char *str;
+       } egl_surf_bits[] = {
+               { EGL_WINDOW_BIT, "win" },
+               { EGL_PIXMAP_BIT, "pix" },
+               { EGL_PBUFFER_BIT, "pbf" },
+               { EGL_MULTISAMPLE_RESOLVE_BOX_BIT, "ms_resolve_box" },
+               { EGL_SWAP_BEHAVIOR_PRESERVED_BIT, "swap_preserved" },
+       };
+
+       for (i = 0; i < ARRAY_LENGTH(egl_surf_bits); i++) {
+               if (egl_surface_type & egl_surf_bits[i].bit) {
+                       fprintf(fp, "%s%s", sep, egl_surf_bits[i].str);
+                       sep = "|";
+               }
+       }
+}
+
 void
 log_egl_config_info(EGLDisplay egldpy, EGLConfig eglconfig)
 {
@@ -211,6 +236,40 @@ egl_config_is_compatible(struct gl_renderer *gr,
        return false;
 }
 
+/* The caller must free() the string */
+static char *
+explain_egl_config_criteria(EGLint egl_surface_type,
+                           const struct pixel_format_info *const *pinfo,
+                           unsigned pinfo_count)
+{
+       FILE *fp;
+       char *str = NULL;
+       size_t size = 0;
+       const char *sep;
+       unsigned i;
+
+       fp = open_memstream(&str, &size);
+       if (!fp)
+               return NULL;
+
+       fputs("{ ", fp);
+
+       print_egl_surface_type_bits(fp, egl_surface_type);
+       fputs("; ", fp);
+
+       sep = "";
+       for (i = 0; i < pinfo_count; i++) {
+               fprintf(fp, "%s%s", sep, pinfo[i]->drm_format_name);
+               sep = ", ";
+       }
+
+       fputs(" }", fp);
+
+       fclose(fp);
+
+       return str;
+}
+
 EGLConfig
 gl_renderer_get_egl_config(struct gl_renderer *gr,
                           EGLint egl_surface_type,
@@ -221,6 +280,7 @@ gl_renderer_get_egl_config(struct gl_renderer *gr,
        const struct pixel_format_info *pinfo[16];
        unsigned pinfo_count;
        unsigned i;
+       char *what;
        EGLint config_attribs[] = {
                EGL_SURFACE_TYPE,    egl_surface_type,
                EGL_RED_SIZE,        1,
@@ -249,7 +309,10 @@ gl_renderer_get_egl_config(struct gl_renderer *gr,
 
        if (egl_choose_config(gr, config_attribs, pinfo, pinfo_count,
                              &egl_config) < 0) {
-               weston_log("No EGLConfig matches.\n");
+               what = explain_egl_config_criteria(egl_surface_type,
+                                                  pinfo, pinfo_count);
+               weston_log("No EGLConfig matches %s.\n", what);
+               free(what);
                return EGL_NO_CONFIG_KHR;
        }
 
@@ -260,9 +323,13 @@ gl_renderer_get_egl_config(struct gl_renderer *gr,
         */
        if (gr->egl_config != EGL_NO_CONFIG_KHR &&
            egl_config != gr->egl_config) {
-               weston_log("Found an EGLConfig but it is not usable because "
-                          "neither EGL_KHR_no_config_context nor "
-                          "EGL_MESA_configless_context are supported by EGL.\n");
+               what = explain_egl_config_criteria(egl_surface_type,
+                                                  pinfo, pinfo_count);
+               weston_log("Found an EGLConfig matching %s but it is not usable"
+                          " because neither EGL_KHR_no_config_context nor "
+                          "EGL_MESA_configless_context are supported by EGL.\n",
+                          what);
+               free(what);
                return EGL_NO_CONFIG_KHR;
        }