buffer_cache: fix the already-disabled check for uniform buffers

DisableGraphicsUniformBuffer tested !current.buffer_id to detect a
binding that is already NULL_BINDING. SlotId converts to true unless it
is the invalid id, and NULL_BUFFER_ID is BufferId{0}, so the check was
false for NULL_BINDING and the early return never triggered. Compare
against NULL_BUFFER_ID instead.

Follow-up to 46b2577bf7.

Assisted-by: Claude Sonnet 5.5 (implementation and commit message)

1 files changed, 2 insertions, 1 deletions

diff --git a/src/video_core/buffer_cache/buffer_cache.h b/src/video_core/buffer_cache/buffer_cache.h
index 6878780866..2d90a949c3 100644
--- a/src/video_core/buffer_cache/buffer_cache.h
+++ b/src/video_core/buffer_cache/buffer_cache.h
@@ -411,7 +411,8 @@ void BufferCache<P>::BindGraphicsUniformBuffer(size_t stage, u32 index, GPUVAddr
 template <class P>
 void BufferCache<P>::DisableGraphicsUniformBuffer(size_t stage, u32 index) {
     auto& current = channel_state->uniform_buffers[stage][index];
-    if (current.device_addr == 0 && current.size == 0 && !current.buffer_id) [[likely]] {
+    if (current.device_addr == 0 && current.size == 0 && current.buffer_id == NULL_BUFFER_ID)
+        [[likely]] {
         return;
     }
     current = NULL_BINDING;