v4l: vsp1: Map the DL and video buffers through the proper bus master

On Gen2 hardware the VSP1 is a bus master and accesses the display list
and video buffers through DMA directly. On Gen3 hardware, however,
memory accesses go through a separate IP core called FCP.

The VSP1 driver unconditionally maps DMA buffers through the VSP device.
While this doesn't cause any practical issue so far, DMA mappings will
be incorrect as soon as we will enable IOMMU support for the FCP on Gen3
platforms, resulting in IOMMU faults.

Fix this by mapping all buffers through the FCP device if present, and
through the VSP1 device as usual otherwise.
Suggested-by: Magnus Damm <magnus.damm@gmail.com>
[Cache the bus master device]
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Acked-by: Mauro Cavalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/vsp1/vsp1.h

@@ -74,6 +74,7 @@ struct vsp1_device {
 
 	void __iomem *mmio;
 	struct rcar_fcp_device *fcp;
+	struct device *bus_master;
 
 	struct vsp1_bru *bru;
 	struct vsp1_clu *clu;

drivers/media/platform/vsp1/vsp1_dl.c

@@ -137,7 +137,7 @@ static int vsp1_dl_body_init(struct vsp1_device *vsp1,
 	dlb->vsp1 = vsp1;
 	dlb->size = size;
 
-	dlb->entries = dma_alloc_wc(vsp1->dev, dlb->size, &dlb->dma,
+	dlb->entries = dma_alloc_wc(vsp1->bus_master, dlb->size, &dlb->dma,
 				    GFP_KERNEL);
 	if (!dlb->entries)
 		return -ENOMEM;
@@ -150,7 +150,7 @@ static int vsp1_dl_body_init(struct vsp1_device *vsp1,
  */
 static void vsp1_dl_body_cleanup(struct vsp1_dl_body *dlb)
 {
-	dma_free_wc(dlb->vsp1->dev, dlb->size, dlb->entries, dlb->dma);
+	dma_free_wc(dlb->vsp1->bus_master, dlb->size, dlb->entries, dlb->dma);
 }
 
 /**

drivers/media/platform/vsp1/vsp1_drv.c

@@ -764,6 +764,15 @@ static int vsp1_probe(struct platform_device *pdev)
 				PTR_ERR(vsp1->fcp));
 			return PTR_ERR(vsp1->fcp);
 		}
+
+		/*
+		 * When the FCP is present, it handles all bus master accesses
+		 * for the VSP and must thus be used in place of the VSP device
+		 * to map DMA buffers.
+		 */
+		vsp1->bus_master = rcar_fcp_get_device(vsp1->fcp);
+	} else {
+		vsp1->bus_master = vsp1->dev;
 	}
 
 	/* Configure device parameters based on the version register. */

drivers/media/platform/vsp1/vsp1_video.c

@@ -1197,7 +1197,7 @@ struct vsp1_video *vsp1_video_create(struct vsp1_device *vsp1,
 	video->queue.ops = &vsp1_video_queue_qops;
 	video->queue.mem_ops = &vb2_dma_contig_memops;
 	video->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
-	video->queue.dev = video->vsp1->dev;
+	video->queue.dev = video->vsp1->bus_master;
 	ret = vb2_queue_init(&video->queue);
 	if (ret < 0) {
 		dev_err(video->vsp1->dev, "failed to initialize vb2 queue\n");