drm/nouveau/instmem/gk20a: use DMA attributes

instmem for GK20A is allocated using dma_alloc_coherent(), which
provides us with a coherent CPU mapping that we never use because
instmem objects are accessed through PRAMIN. Switch to
dma_alloc_attrs() which gives us the option to dismiss that CPU mapping
and free up some CPU virtual space.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
index 9a1fc84..175ac18 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
@@ -24,6 +24,10 @@
 #include <core/mm.h>
 #include <core/device.h>
 
+#ifdef __KERNEL__
+#include <linux/dma-attrs.h>
+#endif
+
 #include "priv.h"
 
 struct gk20a_instobj_priv {
@@ -41,6 +45,7 @@ struct gk20a_instmem_priv {
        struct nvkm_instmem base;
        spinlock_t lock;
        u64 addr;
+       struct dma_attrs attrs;
 };
 
 static u32
@@ -91,8 +96,8 @@ gk20a_instobj_dtor(struct nvkm_object *object)
        if (unlikely(!node->handle))
                return;
 
-       dma_free_coherent(dev, node->mem->size << PAGE_SHIFT, node->cpuaddr,
-                         node->handle);
+       dma_free_attrs(dev, node->mem->size << PAGE_SHIFT, node->cpuaddr,
+                      node->handle, &priv->attrs);
 
        nvkm_instobj_destroy(&node->base);
 }
@@ -126,8 +131,9 @@ gk20a_instobj_ctor(struct nvkm_object *parent, struct nvkm_object *engine,
 
        node->mem = &node->_mem;
 
-       node->cpuaddr = dma_alloc_coherent(dev, npages << PAGE_SHIFT,
-                                          &node->handle, GFP_KERNEL);
+       node->cpuaddr = dma_alloc_attrs(dev, npages << PAGE_SHIFT,
+                                       &node->handle, GFP_KERNEL,
+                                       &priv->attrs);
        if (!node->cpuaddr) {
                nv_error(priv, "cannot allocate DMA memory\n");
                return -ENOMEM;
@@ -195,6 +201,16 @@ gk20a_instmem_ctor(struct nvkm_object *parent, struct nvkm_object *engine,
 
        spin_lock_init(&priv->lock);
 
+       init_dma_attrs(&priv->attrs);
+       /*
+        * We will access instmem through PRAMIN and thus do not need a
+        * consistent CPU pointer or kernel mapping
+        */
+       dma_set_attr(DMA_ATTR_NON_CONSISTENT, &priv->attrs);
+       dma_set_attr(DMA_ATTR_WEAK_ORDERING, &priv->attrs);
+       dma_set_attr(DMA_ATTR_WRITE_COMBINE, &priv->attrs);
+       dma_set_attr(DMA_ATTR_NO_KERNEL_MAPPING, &priv->attrs);
+
        return 0;
 }