[Mesa-dev] [PATCH 5/6] anv/device: Increase the UBO alignment requirement to 32

[Jason Ekstrand]

Push constants work in terms of 32-byte chunks so if we want to be able
to push UBOs, every thing needs to be 32-byte aligned.  Currently, we
only require 16-byte which is too small.
---
 src/intel/vulkan/anv_device.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/intel/vulkan/anv_device.c b/src/intel/vulkan/anv_device.c
index b5577ee..937efb9 100644
--- a/src/intel/vulkan/anv_device.c
+++ b/src/intel/vulkan/anv_device.c
@@ -822,7 +822,8 @@ void anv_GetPhysicalDeviceProperties(
       .viewportSubPixelBits                     = 13, /* We take a float? */
       .minMemoryMapAlignment                    = 4096, /* A page */
       .minTexelBufferOffsetAlignment            = 1,
-      .minUniformBufferOffsetAlignment          = 16,
+      /* We need 16 for UBO block reads to work and 32 for push UBOs */
+      .minUniformBufferOffsetAlignment          = 32,
       .minStorageBufferOffsetAlignment          = 4,
       .minTexelOffset                           = -8,
       .maxTexelOffset                           = 7,
@@ -1833,8 +1834,15 @@ void anv_GetBufferMemoryRequirements(
          memory_types |= (1u << i);
    }
 
+   /* Base alignment requirement of a cache line */
+   uint32_t alignment = 16;
+
+   /* We need an alignment of 32 for pushing UBOs */
+   if (buffer->usage & VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT)
+      alignment = MAX2(alignment, 32);
+
    pMemoryRequirements->size = buffer->size;
-   pMemoryRequirements->alignment = 16;
+   pMemoryRequirements->alignment = alignment;
    pMemoryRequirements->memoryTypeBits = memory_types;
 }
 
-- 
2.5.0.400.gff86faf