[Mesa-dev] [PATCH 3/3] radv: enable TC-compat HTILE for 16-bit depth surfaces on GFX8

[Samuel Pitoiset]

The hardware only supports 32-bit depth surfaces, but we can
enable TC-compat HTILE for 16-bit depth surfaces if no Z planes
are compressed.

The main benefit is to reduce the number of depth decompression
passes. Also, we don't need to implement DB->CB copies which is
fine.

This improves Serious Sam 2017 by +4%. Talos and F12017 are also
affected but I don't see a performance difference.

This also improves the shadowmapping Vulkan demo by 10-15%
(FPS is now similar to AMDVLK).

No CTS regressions on Polaris10.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
---
 src/amd/vulkan/radv_device.c | 22 ++++++++++++++++------
 src/amd/vulkan/radv_image.c  | 20 ++++++++------------
 2 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/src/amd/vulkan/radv_device.c b/src/amd/vulkan/radv_device.c
index 22500bfc13..9c82fd059f 100644
--- a/src/amd/vulkan/radv_device.c
+++ b/src/amd/vulkan/radv_device.c
@@ -3615,12 +3615,22 @@ radv_calc_decompress_on_z_planes(struct radv_device *device,
 
 		max_zplanes = max_zplanes + 1;
 	} else {
-		if (iview->image->info.samples <= 1)
-			max_zplanes = 5;
-		else if (iview->image->info.samples <= 4)
-			max_zplanes = 3;
-		else
-			max_zplanes = 2;
+		if (iview->vk_format == VK_FORMAT_D16_UNORM) {
+			/* Do not enable Z plane compression for 16-bit depth
+			 * surfaces because isn't supported on GFX8. Only
+			 * 32-bit depth surfaces are supported by the hardware.
+			 * This allows to maintain shader compatibility and to
+			 * reduce the number of depth decompressions.
+			 */
+			max_zplanes = 1;
+		} else {
+			if (iview->image->info.samples <= 1)
+				max_zplanes = 5;
+			else if (iview->image->info.samples <= 4)
+				max_zplanes = 3;
+			else
+				max_zplanes = 2;
+		}
 	}
 
 	return max_zplanes;
diff --git a/src/amd/vulkan/radv_image.c b/src/amd/vulkan/radv_image.c
index 6e5f3e7ad0..dd3189c67d 100644
--- a/src/amd/vulkan/radv_image.c
+++ b/src/amd/vulkan/radv_image.c
@@ -91,18 +91,14 @@ radv_image_is_tc_compat_htile(struct radv_device *device,
 	    pCreateInfo->format == VK_FORMAT_D32_SFLOAT_S8_UINT)
 		return false;
 
-	if (device->physical_device->rad_info.chip_class >= GFX9) {
-		/* GFX9 supports both 32-bit and 16-bit depth surfaces. */
-		if (pCreateInfo->format != VK_FORMAT_D32_SFLOAT_S8_UINT &&
-		    pCreateInfo->format != VK_FORMAT_D32_SFLOAT &&
-		    pCreateInfo->format != VK_FORMAT_D16_UNORM)
-			return false;
-	} else {
-		/* GFX8 only supports 32-bit depth surfaces. */
-		if (pCreateInfo->format != VK_FORMAT_D32_SFLOAT_S8_UINT &&
-		    pCreateInfo->format != VK_FORMAT_D32_SFLOAT)
-			return false;
-	}
+	/* GFX9 supports both 32-bit and 16-bit depth surfaces, while GFX8 only
+	 * supports 32-bit. Though, it's possible to enable TC-compat for
+	 * 16-bit depth surfaces if no Z planes are compressed.
+	 */
+	if (pCreateInfo->format != VK_FORMAT_D32_SFLOAT_S8_UINT &&
+	    pCreateInfo->format != VK_FORMAT_D32_SFLOAT &&
+	    pCreateInfo->format != VK_FORMAT_D16_UNORM)
+		return false;
 
 	return true;
 }
-- 
2.16.2