[PATCH 2/3] rpmsg: virtio_rpmsg_bus: allocate rx/tx buffer separately

[Xiang Xiao]

many dma allocator align the returned address with buffer size,
so two small allocation could reduce the alignment requirement
and save the the memory space wasted by the potential alignment.

Signed-off-by: Xiang Xiao <xiaoxiang@xxxxxxxxxx>
---
 drivers/rpmsg/virtio_rpmsg_bus.c | 58 +++++++++++++++++++++++-----------------
 1 file changed, 34 insertions(+), 24 deletions(-)

diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index fb0d2eb..59c4554 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c
@@ -40,7 +40,8 @@
  * @num_sbufs:	total number of buffers for tx
  * @buf_size:	size of one rx or tx buffer
  * @last_sbuf:	index of last tx buffer used
- * @bufs_dma:	dma base addr of the buffers
+ * @rbufs_dma:	dma base addr of rx buffers
+ * @sbufs_dma:	dma base addr of tx buffers
  * @tx_lock:	protects svq, sbufs and sleepers, to allow concurrent senders.
  *		sending a message might require waking up a dozing remote
  *		processor, which involves sleeping, hence the mutex.
@@ -62,7 +63,8 @@ struct virtproc_info {
 	unsigned int num_sbufs;
 	unsigned int buf_size;
 	int last_sbuf;
-	dma_addr_t bufs_dma;
+	dma_addr_t rbufs_dma;
+	dma_addr_t sbufs_dma;
 	struct mutex tx_lock;
 	struct idr endpoints;
 	struct mutex endpoints_lock;
@@ -872,9 +874,7 @@ static int rpmsg_probe(struct virtio_device *vdev)
 	static const char * const names[] = { "input", "output" };
 	struct virtqueue *vqs[2];
 	struct virtproc_info *vrp;
-	void *bufs_va;
 	int err = 0, i;
-	size_t total_buf_space;
 	bool notify;
 
 	vrp = kzalloc(sizeof(*vrp), GFP_KERNEL);
@@ -909,25 +909,28 @@ static int rpmsg_probe(struct virtio_device *vdev)
 
 	vrp->buf_size = MAX_RPMSG_BUF_SIZE;
 
-	total_buf_space = (vrp->num_rbufs + vrp->num_sbufs) * vrp->buf_size;
-
 	/* allocate coherent memory for the buffers */
-	bufs_va = dma_alloc_coherent(vdev->dev.parent->parent,
-				     total_buf_space, &vrp->bufs_dma,
-				     GFP_KERNEL);
-	if (!bufs_va) {
+	vrp->rbufs = dma_alloc_coherent(vdev->dev.parent->parent,
+					vrp->num_rbufs * vrp->buf_size,
+					&vrp->rbufs_dma, GFP_KERNEL);
+	if (!vrp->rbufs) {
 		err = -ENOMEM;
 		goto vqs_del;
 	}
 
-	dev_dbg(&vdev->dev, "buffers: va %p, dma %pad\n",
-		bufs_va, &vrp->bufs_dma);
+	dev_dbg(&vdev->dev, "rx buffers: va %p, dma 0x%pad\n",
+		vrp->rbufs, &vrp->rbufs_dma);
 
-	/* first part of the buffers is dedicated for RX */
-	vrp->rbufs = bufs_va;
+	vrp->sbufs = dma_alloc_coherent(vdev->dev.parent->parent,
+					vrp->num_sbufs * vrp->buf_size,
+					&vrp->sbufs_dma, GFP_KERNEL);
+	if (!vrp->sbufs) {
+		err = -ENOMEM;
+		goto free_rbufs;
+	}
 
-	/* and second part is dedicated for TX */
-	vrp->sbufs = bufs_va + vrp->num_rbufs * vrp->buf_size;
+	dev_dbg(&vdev->dev, "tx buffers: va %p, dma 0x%pad\n",
+		vrp->sbufs, &vrp->sbufs_dma);
 
 	/* set up the receive buffers */
 	for (i = 0; i < vrp->num_rbufs; i++) {
@@ -954,7 +957,7 @@ static int rpmsg_probe(struct virtio_device *vdev)
 		if (!vrp->ns_ept) {
 			dev_err(&vdev->dev, "failed to create the ns ept\n");
 			err = -ENOMEM;
-			goto free_coherent;
+			goto free_sbufs;
 		}
 	}
 
@@ -979,9 +982,14 @@ static int rpmsg_probe(struct virtio_device *vdev)
 
 	return 0;
 
-free_coherent:
-	dma_free_coherent(vdev->dev.parent->parent, total_buf_space,
-			  bufs_va, vrp->bufs_dma);
+free_sbufs:
+	dma_free_coherent(vdev->dev.parent->parent,
+			  vrp->num_sbufs * vrp->buf_size,
+			  vrp->sbufs, vrp->sbufs_dma);
+free_rbufs:
+	dma_free_coherent(vdev->dev.parent->parent,
+			  vrp->num_rbufs * vrp->buf_size,
+			  vrp->rbufs, vrp->rbufs_dma);
 vqs_del:
 	vdev->config->del_vqs(vrp->vdev);
 free_vrp:
@@ -999,8 +1007,6 @@ static int rpmsg_remove_device(struct device *dev, void *data)
 static void rpmsg_remove(struct virtio_device *vdev)
 {
 	struct virtproc_info *vrp = vdev->priv;
-	unsigned int num_bufs = vrp->num_rbufs + vrp->num_sbufs;
-	size_t total_buf_space = num_bufs * vrp->buf_size;
 	int ret;
 
 	vdev->config->reset(vdev);
@@ -1016,8 +1022,12 @@ static void rpmsg_remove(struct virtio_device *vdev)
 
 	vdev->config->del_vqs(vrp->vdev);
 
-	dma_free_coherent(vdev->dev.parent->parent, total_buf_space,
-			  vrp->rbufs, vrp->bufs_dma);
+	dma_free_coherent(vdev->dev.parent->parent,
+			  vrp->num_sbufs * vrp->buf_size,
+			  vrp->sbufs, vrp->sbufs_dma);
+	dma_free_coherent(vdev->dev.parent->parent,
+			  vrp->num_rbufs * vrp->buf_size,
+			  vrp->rbufs, vrp->rbufs_dma);
 
 	kfree(vrp);
 }
-- 
2.7.4