display: fix validation process of properties during discovery.

Some VA drivers (e.g. EMGD) can have completely random values for initial
display attributes. So, try to improve the discovery process to check the
initial display attribute values actually fall within valid bounds. If not,
try to reset those to some sensible values like the default value reported
through vaQueryDisplayAttributes().

diff --git a/gst-libs/gst/vaapi/gstvaapidisplay.c b/gst-libs/gst/vaapi/gstvaapidisplay.c
index 985c281..96a7209 100644 (file)
--- a/gst-libs/gst/vaapi/gstvaapidisplay.c
+++ b/gst-libs/gst/vaapi/gstvaapidisplay.c
@@ -609,6 +609,7 @@ gst_vaapi_display_create(GstVaapiDisplay *display)
     for (i = 0; i < n; i++) {
         VADisplayAttribute * const attr = &display_attrs[i];
         GstVaapiProperty prop;
+        gint value;
 
         GST_DEBUG("  %s", string_of_VADisplayAttributeType(attr->type));
 
@@ -645,9 +646,24 @@ gst_vaapi_display_create(GstVaapiDisplay *display)
 
         /* Assume the attribute is really supported if we can get the
          * actual and current value */
+        if (!get_attribute(display, attr->type, &value))
+            continue;
+
+        /* Some drivers (e.g. EMGD) have completely random initial
+         * values. So try to reset sensible ones */
+        if (value < attr->min_value || value > attr->max_value) {
+            gint v;
+            if (!(attr->flags & VA_DISPLAY_ATTRIB_SETTABLE))
+                continue;
+            if (!set_attribute(display, attr->type, attr->value))
+                continue;
+            if (!get_attribute(display, attr->type, &v) || v != value)
+                continue;
+        }
+
         prop.attribute = *attr;
-        if (get_attribute(display, attr->type, &prop.old_value))
-            g_array_append_val(priv->properties, prop);
+        prop.old_value = value;
+        g_array_append_val(priv->properties, prop);
     }
 
     /* VA image formats */