gpu: nvgpu: cache cde compbits buf mappings

don't unmap compbits_buf explicitly from system vm early but store it in
the dmabuf's private data, and unmap it later when all user mappings to
that buffer have been disappeared.

Bug 1546619

Change-Id: I333235a0ea74c48503608afac31f5e9f1eb4b99b
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/661949
(cherry picked from commit ed2177e25d9e5facfb38786b818330798a14b9bb)
Reviewed-on: http://git-master/r/661835
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 18 insertions, 14 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/cde_gk20a.c b/drivers/gpu/nvgpu/gk20a/cde_gk20a.c
index 57283343..49a1c1a8 100644
--- a/drivers/gpu/nvgpu/gk20a/cde_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/cde_gk20a.c
@@ -1,7 +1,7 @@
 /*
  * Color decompression engine support
  *
- * Copyright (c) 2014, NVIDIA Corporation.  All rights reserved.
+ * Copyright (c) 2014-2015, NVIDIA Corporation.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -979,17 +979,23 @@ __releases(&cde_app->mutex)
                 map_size = compbits_buf->size - map_offset;
         }
 
-        /* map the destination buffer */
-        get_dma_buf(compbits_buf); /* a ref for gk20a_vm_map */
-        map_vaddr = gk20a_vm_map(cde_ctx->vm, compbits_buf, 0,
-                                 NVGPU_MAP_BUFFER_FLAGS_CACHEABLE_TRUE,
-                                 compbits_kind, NULL, true,
-                                 gk20a_mem_flag_none,
-                                 map_offset, map_size);
+        /* map the destination buffer, if not cached yet */
+        /* races protected by the cde app mutex above */
+        map_vaddr = gk20a_vm_cde_mapped(cde_ctx->vm, compbits_buf);
         if (!map_vaddr) {
-                dma_buf_put(compbits_buf);
-                err = -EINVAL;
-                goto exit_unlock;
+                /* take a ref for gk20a_vm_map, pair is in (cached) unmap */
+                get_dma_buf(compbits_buf);
+                map_vaddr = gk20a_vm_map(cde_ctx->vm, compbits_buf, 0,
+                                NVGPU_MAP_BUFFER_FLAGS_CACHEABLE_TRUE,
+                                compbits_kind, NULL, true,
+                                gk20a_mem_flag_none,
+                                map_offset, map_size);
+                if (!map_vaddr) {
+                        dma_buf_put(compbits_buf);
+                        err = -EINVAL;
+                        goto exit_unlock;
+                }
+                gk20a_vm_mark_cde_mapped(cde_ctx->vm, compbits_buf, map_vaddr);
         }
 
         /* store source buffer compression tags */
@@ -1052,9 +1058,7 @@ __releases(&cde_app->mutex)
 
 exit_unlock:
 
-        /* unmap the buffers - channel holds references to them now */
-        if (map_vaddr)
-                gk20a_vm_unmap(cde_ctx->vm, map_vaddr);
+        /* leave map_vaddr mapped - released when unmapped from userspace */
 
         mutex_unlock(&g->cde_app.mutex);
         return err;