zink: add a function for getting the minimum framebuffer layers

this clamps the layer count to the smallest number of layers rather
than the largest

cc: mesa-stable

Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17061>

diff --git a/src/gallium/drivers/zink/zink_framebuffer.c b/src/gallium/drivers/zink/zink_framebuffer.c
index 84f410d..e0bc32d 100644 (file)
--- a/src/gallium/drivers/zink/zink_framebuffer.c
+++ b/src/gallium/drivers/zink/zink_framebuffer.c
@@ -219,3 +219,26 @@ zink_update_framebuffer_state(struct zink_context *ctx)
    ctx->fb_changed |= ctx->framebuffer != fb;
    ctx->framebuffer = fb;
 }
+
+/* same as u_framebuffer_get_num_layers, but clamp to lowest layer count */
+unsigned
+zink_framebuffer_get_num_layers(const struct pipe_framebuffer_state *fb)
+{
+   unsigned i, num_layers = UINT32_MAX;
+   if (!(fb->nr_cbufs || fb->zsbuf))
+      return MAX2(fb->layers, 1);
+
+   for (i = 0; i < fb->nr_cbufs; i++) {
+      if (fb->cbufs[i]) {
+         unsigned num = fb->cbufs[i]->u.tex.last_layer -
+         fb->cbufs[i]->u.tex.first_layer + 1;
+         num_layers = MIN2(num_layers, num);
+      }
+   }
+   if (fb->zsbuf) {
+      unsigned num = fb->zsbuf->u.tex.last_layer -
+      fb->zsbuf->u.tex.first_layer + 1;
+      num_layers = MIN2(num_layers, num);
+   }
+   return MAX2(num_layers, 1);
+}

diff --git a/src/gallium/drivers/zink/zink_framebuffer.h b/src/gallium/drivers/zink/zink_framebuffer.h
index 7544074..e129183 100644 (file)
--- a/src/gallium/drivers/zink/zink_framebuffer.h
+++ b/src/gallium/drivers/zink/zink_framebuffer.h
@@ -87,4 +87,6 @@ zink_get_framebuffer(struct zink_context *ctx);
 
 void
 zink_update_framebuffer_state(struct zink_context *ctx);
+unsigned
+zink_framebuffer_get_num_layers(const struct pipe_framebuffer_state *fb);
 #endif