From 0c283ca15627954239913de43e386aaf2a4b7675 Mon Sep 17 00:00:00 2001
From: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Date: Wed, 15 Jun 2022 12:58:03 -0400
Subject: [PATCH] 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>
(cherry picked from commit f74df6205d245491a8a54ffa6e737f22b9b00fb4)

Conflicts:
	src/gallium/drivers/zink/zink_framebuffer.h
---
 .pick_status.json                           |  2 +-
 src/gallium/drivers/zink/zink_framebuffer.c | 23 +++++++++++++++++++++
 src/gallium/drivers/zink/zink_framebuffer.h |  4 ++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/.pick_status.json b/.pick_status.json
index fe8b2b4058b..cd8a0908a05 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -895,7 +895,7 @@
         "description": "zink: add a function for getting the minimum framebuffer layers",
         "nominated": true,
         "nomination_type": 0,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": null
     },
diff --git a/src/gallium/drivers/zink/zink_framebuffer.c b/src/gallium/drivers/zink/zink_framebuffer.c
index fd21a695c95..99aead406ae 100644
--- a/src/gallium/drivers/zink/zink_framebuffer.c
+++ b/src/gallium/drivers/zink/zink_framebuffer.c
@@ -378,3 +378,26 @@ zink_get_framebuffer(struct zink_context *ctx)
 
    return 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 4fb8bf67b90..d157be96ee5 100644
--- a/src/gallium/drivers/zink/zink_framebuffer.h
+++ b/src/gallium/drivers/zink/zink_framebuffer.h
@@ -95,4 +95,8 @@ zink_get_framebuffer_imageless(struct zink_context *ctx);
 
 struct zink_framebuffer *
 zink_get_framebuffer(struct zink_context *ctx);
+
+unsigned
+zink_framebuffer_get_num_layers(const struct pipe_framebuffer_state *fb);
+
 #endif