diff --git a/src/panfrost/lib/pan_layout.c b/src/panfrost/lib/pan_layout.c
index 04751c9572e..309f4895c30 100644
--- a/src/panfrost/lib/pan_layout.c
+++ b/src/panfrost/lib/pan_layout.c
@@ -104,6 +104,17 @@ panfrost_afbc_is_wide(uint64_t modifier)
    return panfrost_afbc_superblock_width(modifier) > 16;
 }
 
+/*
+ * Given an AFBC modifier, return the subblock size (subdivision of a
+ * superblock). This is always 4x4 for now as we only support one AFBC
+ * superblock layout.
+ */
+struct pan_block_size
+panfrost_afbc_subblock_size(uint64_t modifier)
+{
+   return (struct pan_block_size){4, 4};
+}
+
 /*
  * Given a format, determine the tile size used for u-interleaving. For formats
  * that are already block compressed, this is 4x4. For all other formats, this
diff --git a/src/panfrost/lib/pan_texture.h b/src/panfrost/lib/pan_texture.h
index 001818320a9..80028be275b 100644
--- a/src/panfrost/lib/pan_texture.h
+++ b/src/panfrost/lib/pan_texture.h
@@ -249,6 +249,8 @@ unsigned panfrost_afbc_superblock_height(uint64_t modifier);
 
 bool panfrost_afbc_is_wide(uint64_t modifier);
 
+struct pan_block_size panfrost_afbc_subblock_size(uint64_t modifier);
+
 uint32_t pan_afbc_row_stride(uint64_t modifier, uint32_t width);
 
 uint32_t pan_afbc_stride_blocks(uint64_t modifier, uint32_t row_stride_bytes);