[Mesa-dev] [PATCH 4/6] [v2] i965: Handle Y-tiled modifier

[Ben Widawsky]

This patch begins introducing how we'll actually handle the potentially
many modifiers coming in from the API, how we'll store them, and the
structure in the code to support it.

Prior to this patch, the Y-tiled modifier would be entirely ignored. It
shouldn't actually be used until this point because we've not bumped the
DRIimage extension version (which is a requirement to use modifiers).

Measuring later in the series with kmscbe:
Linear:
Read bandwidth: 1048.44 MiB/s
Write bandwidth: 1483.17 MiB/s

Y-tiled:
Read bandwidth: 471.13 MiB/s
Write bandwidth: 589.10 MiB/s

Similar functionality was introduced and then reverted here:

commit 6a0d036483caf87d43ebe2edd1905873446c9589
Author: Ben Widawsky <ben at bwidawsk.net>
Date:   Thu Apr 21 20:14:58 2016 -0700

    i965: Always use Y-tiled buffers on SKL+

v2: Use last set bit instead of first set bit in modifiers to address
bug found by Daniel Stone.

v3: Use the new priority modifier selection thing. This nullifies the
bug fixed by v2 also.

Signed-off-by: Ben Widawsky <benjamin.widawsky at intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom at imgtec.com>
Acked-by: Daniel Stone <daniels at collabora.com>
---
 src/gbm/backends/dri/gbm_dri.c           | 18 ++++++++++++++++
 src/mesa/drivers/dri/i965/intel_screen.c | 36 ++++++++++++++++++++++++++++----
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/src/gbm/backends/dri/gbm_dri.c b/src/gbm/backends/dri/gbm_dri.c
index a7ac149365..a78ea89fca 100644
--- a/src/gbm/backends/dri/gbm_dri.c
+++ b/src/gbm/backends/dri/gbm_dri.c
@@ -1143,6 +1143,15 @@ gbm_dri_bo_create(struct gbm_device *gbm,
          goto failed;
       }
 
+      if (modifiers) {
+         for (int i = 0; i < count; i++)
+            if (modifiers[i] == DRM_FORMAT_MOD_INVALID) {
+               fprintf(stderr, "Invalid modifier passed in DRM_FORMAT_MOD_INVALID");
+               errno = EINVAL;
+               goto failed;
+            }
+      }
+
       bo->image =
          dri->image->createImageWithModifiers(dri->screen,
                                               width, height,
@@ -1240,6 +1249,15 @@ gbm_dri_surface_create(struct gbm_device *gbm,
       return NULL;
    }
 
+   if (modifiers) {
+      for (int i = 0; i < count; i++)
+         if (modifiers[i] == DRM_FORMAT_MOD_INVALID) {
+            fprintf(stderr, "Invalid modifier passed in DRM_FORMAT_MOD_INVALID");
+            errno = EINVAL;
+            return NULL;
+         }
+   }
+
    surf = calloc(1, sizeof *surf);
    if (surf == NULL) {
       errno = ENOMEM;
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 14e60ef1a1..e4f858ed33 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -23,6 +23,7 @@
  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <drm_fourcc.h>
 #include <errno.h>
 #include <time.h>
 #include <unistd.h>
@@ -518,11 +519,13 @@ intel_destroy_image(__DRIimage *image)
 enum modifier_priority {
    MODIFIER_PRIORITY_INVALID = 0,
    MODIFIER_PRIORITY_LINEAR,
+   MODIFIER_PRIORITY_Y,
 };
 
 const uint64_t priority_to_modifier[] = {
    [MODIFIER_PRIORITY_INVALID] = DRM_FORMAT_MOD_INVALID,
    [MODIFIER_PRIORITY_LINEAR] = DRM_FORMAT_MOD_LINEAR,
+   [MODIFIER_PRIORITY_Y] = I915_FORMAT_MOD_Y_TILED,
 };
 
 static uint64_t
@@ -530,11 +533,13 @@ select_best_modifier(struct gen_device_info *devinfo,
                      const uint64_t *modifiers,
                      const unsigned count)
 {
-
    enum modifier_priority prio = MODIFIER_PRIORITY_INVALID;
 
    for (int i = 0; i < count; i++) {
       switch (modifiers[i]) {
+      case I915_FORMAT_MOD_Y_TILED:
+         prio = MAX2(prio, MODIFIER_PRIORITY_Y);
+         break;
       case DRM_FORMAT_MOD_LINEAR:
          prio = MAX2(prio, MODIFIER_PRIORITY_LINEAR);
          break;
@@ -575,6 +580,9 @@ intel_create_image_common(__DRIscreen *dri_screen,
    case DRM_FORMAT_MOD_LINEAR:
       tiling = I915_TILING_NONE;
       break;
+   case I915_FORMAT_MOD_Y_TILED:
+      tiling = I915_TILING_Y;
+      break;
    case DRM_FORMAT_MOD_INVALID:
    default:
          break;
@@ -626,8 +634,26 @@ intel_create_image_with_modifiers(__DRIscreen *dri_screen,
                                   const unsigned count,
                                   void *loaderPrivate)
 {
-   return intel_create_image_common(dri_screen, width, height, format, 0, NULL,
-                                    0, loaderPrivate);
+   uint64_t local_mods[count];
+   int local_count = 0;
+
+   /* This compacts the actual modifiers to the ones we know how to handle */
+   for (int i = 0; i < count; i++) {
+      switch (modifiers[i]) {
+      case I915_FORMAT_MOD_Y_TILED:
+      case DRM_FORMAT_MOD_LINEAR:
+         local_mods[local_count++] = modifiers[i];
+         break;
+      case DRM_FORMAT_MOD_INVALID:
+         unreachable("Invalid modifiers specified\n");
+      default:
+         /* Modifiers from other vendors would land here. */
+         break;
+      }
+   }
+
+   return intel_create_image_common(dri_screen, width, height, format, 0,
+                                    local_mods, local_count, loaderPrivate);
 }
 
 static GLboolean
@@ -1997,7 +2023,9 @@ intelAllocateBuffer(__DRIscreen *dri_screen,
    if (intelBuffer == NULL)
       return NULL;
 
-   /* The front and back buffers are color buffers, which are X tiled. */
+   /* The front and back buffers are color buffers, which are X tiled. GEN9+
+    * supports Y tiled and compressed buffers, but there is no way to plumb that
+    * through to here. */
    uint32_t tiling = I915_TILING_X;
    unsigned long pitch;
    int cpp = format / 8;
-- 
2.12.0