drm/prime: support to cache mapping

The drm prime also can support it like GEM CMA supports to cache
mapping. It doesn't allow multiple mappings for one attachment.

[airlied: rebased on top of other prime changes]
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 49 insertions, 3 deletions

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 4ad2c45090b3..b1cd47438850 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -62,15 +62,29 @@ struct drm_prime_member {
         struct dma_buf *dma_buf;
         uint32_t handle;
 };
+
+struct drm_prime_attachment {
+        struct sg_table *sgt;
+        enum dma_data_direction dir;
+};
+
 static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle);
 
 static int drm_gem_map_attach(struct dma_buf *dma_buf,
                               struct device *target_dev,
                               struct dma_buf_attachment *attach)
 {
+        struct drm_prime_attachment *prime_attach;
         struct drm_gem_object *obj = dma_buf->priv;
         struct drm_device *dev = obj->dev;
 
+        prime_attach = kzalloc(sizeof(*prime_attach), GFP_KERNEL);
+        if (!prime_attach)
+                return -ENOMEM;
+
+        prime_attach->dir = DMA_NONE;
+        attach->priv = prime_attach;
+
         if (!dev->driver->gem_prime_pin)
                 return 0;
 
@@ -80,19 +94,50 @@ static int drm_gem_map_attach(struct dma_buf *dma_buf,
 static void drm_gem_map_detach(struct dma_buf *dma_buf,
                                struct dma_buf_attachment *attach)
 {
+        struct drm_prime_attachment *prime_attach = attach->priv;
         struct drm_gem_object *obj = dma_buf->priv;
         struct drm_device *dev = obj->dev;
+        struct sg_table *sgt;
 
         if (dev->driver->gem_prime_unpin)
                 dev->driver->gem_prime_unpin(obj);
+
+        if (!prime_attach)
+                return;
+
+        sgt = prime_attach->sgt;
+
+        if (prime_attach->dir != DMA_NONE)
+                dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents,
+                                prime_attach->dir);
+
+        sg_free_table(sgt);
+        kfree(sgt);
+        kfree(prime_attach);
+        attach->priv = NULL;
 }
 
 static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
                 enum dma_data_direction dir)
 {
+        struct drm_prime_attachment *prime_attach = attach->priv;
         struct drm_gem_object *obj = attach->dmabuf->priv;
         struct sg_table *sgt;
 
+        if (WARN_ON(dir == DMA_NONE || !prime_attach))
+                return ERR_PTR(-EINVAL);
+
+        /* return the cached mapping when possible */
+        if (prime_attach->dir == dir)
+                return prime_attach->sgt;
+
+        /*
+         * two mappings with different directions for the same attachment are
+         * not allowed
+         */
+        if (WARN_ON(prime_attach->dir != DMA_NONE))
+                return ERR_PTR(-EBUSY);
+
         mutex_lock(&obj->dev->struct_mutex);
 
         sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
@@ -102,6 +147,9 @@ static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
                         sg_free_table(sgt);
                         kfree(sgt);
                         sgt = ERR_PTR(-ENOMEM);
+                } else {
+                        prime_attach->sgt = sgt;
+                        prime_attach->dir = dir;
                 }
         }
 
@@ -112,9 +160,7 @@ static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
 static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
                 struct sg_table *sgt, enum dma_data_direction dir)
 {
-        dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
-        sg_free_table(sgt);
-        kfree(sgt);
+        /* nothing to be done here */
 }
 
 static void drm_gem_dmabuf_release(struct dma_buf *dma_buf)