Mesa (master): svga: Fix banded DMA upload

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Module: Mesa
Branch: master
Commit: 451cf228d53ba8f51beb3dcf04370e126fb7ccb6
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=451cf228d53ba8f51beb3dcf04370e126fb7ccb6

Author: Thomas Hellstrom <thellstrom at vmware.com>
Date:   Wed Feb  5 07:54:19 2020 +0100

svga: Fix banded DMA upload

A previous commit ("winsys/svga: Limit the maximum DMA hardware buffer
size") made banded DMA transfer kick in when transfering gnome-shell
window contents under gnome-shell / wayland. This uncovered a bug where
we assumed that banded DMA transfers always occur to the top (y=0) of the
surface.
Fix this by taking the destination y offset into account.

Cc: 19.2 19.3 20.0 <mesa-stable at lists.freedesktop.org>
Fixes: 287c94ea498 ("Squashed commit of the following:")
Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
Reviewed-by: Brian Paul <brianp at vmware.com>
Reviewed-by: Charmaine Lee <charmainel at vmware.com>
Reviewed-by: Roland Scheidegger <sroland at vmware.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3733>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3733>

---

 src/gallium/drivers/svga/svga_resource_texture.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/gallium/drivers/svga/svga_resource_texture.c b/src/gallium/drivers/svga/svga_resource_texture.c
index b57d2d7ee95..4cc58e001c0 100644
--- a/src/gallium/drivers/svga/svga_resource_texture.c
+++ b/src/gallium/drivers/svga/svga_resource_texture.c
@@ -133,25 +133,26 @@ svga_transfer_dma(struct svga_context *svga,
       }
    }
    else {
-      int y, h, srcy;
+      int y, h, y_max;
       unsigned blockheight =
          util_format_get_blockheight(st->base.resource->format);
 
       h = st->hw_nblocksy * blockheight;
-      srcy = 0;
+      y_max = st->box.y + st->box.h;
 
-      for (y = 0; y < st->box.h; y += h) {
+      for (y = st->box.y; y < y_max; y += h) {
          unsigned offset, length;
          void *hw, *sw;
 
-         if (y + h > st->box.h)
-            h = st->box.h - y;
+         if (y + h > y_max)
+            h = y_max - y;
 
          /* Transfer band must be aligned to pixel block boundaries */
          assert(y % blockheight == 0);
          assert(h % blockheight == 0);
 
-         offset = y * st->base.stride / blockheight;
+         /* First band starts at the top of the SW buffer. */
+         offset = (y - st->box.y) * st->base.stride / blockheight;
          length = h * st->base.stride / blockheight;
 
          sw = (uint8_t *) st->swbuf + offset;
@@ -159,9 +160,9 @@ svga_transfer_dma(struct svga_context *svga,
          if (transfer == SVGA3D_WRITE_HOST_VRAM) {
             unsigned usage = PIPE_TRANSFER_WRITE;
 
-            /* Wait for the previous DMAs to complete */
-            /* TODO: keep one DMA (at half the size) in the background */
-            if (y) {
+            /* Don't write to an in-flight DMA buffer. Synchronize or
+             * discard in-flight storage. */
+            if (y != st->box.y) {
                svga_context_flush(svga, NULL);
                usage |= PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE;
             }
@@ -177,7 +178,7 @@ svga_transfer_dma(struct svga_context *svga,
          svga_transfer_dma_band(svga, st, transfer,
                                 st->box.x, y, st->box.z,
                                 st->box.w, h, st->box.d,
-                                0, srcy, 0, flags);
+                                0, 0, 0, flags);
 
          /*
           * Prevent the texture contents to be discarded on the next band