V4L/DVB (11320): pxa_camera: Remove YUV planar formats hole

All planes were PAGE aligned (ie. 4096 bytes aligned). This
is not consistent with YUV422 format, which requires Y, U
and V planes glued together.  The new implementation forces
the alignement on 8 bytes (DMA requirement), which is almost
always the case (granted by width x height being a multiple
of 8).

The test cases include tests in both YUV422 and RGB565 :
 - a picture of size 111 x 111 (cross RAM pages example)
 - a picture of size 1023 x 4 in (under 1 RAM page)
 - a picture of size 1024 x 4 in (exactly 1 RAM page)
 - a picture of size 1025 x 4 in (over 1 RAM page)
 - a picture of size 1280 x 1024 (many RAM pages)

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/pxa_camera.c

@@ -287,48 +287,118 @@ static void free_buffer(struct videobuf_queue *vq, struct pxa_buffer *buf)
 	buf->vb.state = VIDEOBUF_NEEDS_INIT;
 }
 
+static int calculate_dma_sglen(struct scatterlist *sglist, int sglen,
+			       int sg_first_ofs, int size)
+{
+	int i, offset, dma_len, xfer_len;
+	struct scatterlist *sg;
+
+	offset = sg_first_ofs;
+	for_each_sg(sglist, sg, sglen, i) {
+		dma_len = sg_dma_len(sg);
+
+		/* PXA27x Developer's Manual 27.4.4.1: round up to 8 bytes */
+		xfer_len = roundup(min(dma_len - offset, size), 8);
+
+		size = max(0, size - xfer_len);
+		offset = 0;
+		if (size == 0)
+			break;
+	}
+
+	BUG_ON(size != 0);
+	return i + 1;
+}
+
+/**
+ * pxa_init_dma_channel - init dma descriptors
+ * @pcdev: pxa camera device
+ * @buf: pxa buffer to find pxa dma channel
+ * @dma: dma video buffer
+ * @channel: dma channel (0 => 'Y', 1 => 'U', 2 => 'V')
+ * @cibr: camera Receive Buffer Register
+ * @size: bytes to transfer
+ * @sg_first: first element of sg_list
+ * @sg_first_ofs: offset in first element of sg_list
+ *
+ * Prepares the pxa dma descriptors to transfer one camera channel.
+ * Beware sg_first and sg_first_ofs are both input and output parameters.
+ *
+ * Returns 0 or -ENOMEM if no coherent memory is available
+ */
 static int pxa_init_dma_channel(struct pxa_camera_dev *pcdev,
 				struct pxa_buffer *buf,
 				struct videobuf_dmabuf *dma, int channel,
-				int sglen, int sg_start, int cibr,
-				unsigned int size)
+				int cibr, int size,
+				struct scatterlist **sg_first, int *sg_first_ofs)
 {
 	struct pxa_cam_dma *pxa_dma = &buf->dmas[channel];
-	int i;
+	struct scatterlist *sg;
+	int i, offset, sglen;
+	int dma_len = 0, xfer_len = 0;
 
 	if (pxa_dma->sg_cpu)
 		dma_free_coherent(pcdev->dev, pxa_dma->sg_size,
 				  pxa_dma->sg_cpu, pxa_dma->sg_dma);
 
+	sglen = calculate_dma_sglen(*sg_first, dma->sglen,
+				    *sg_first_ofs, size);
+
 	pxa_dma->sg_size = (sglen + 1) * sizeof(struct pxa_dma_desc);
 	pxa_dma->sg_cpu = dma_alloc_coherent(pcdev->dev, pxa_dma->sg_size,
 					     &pxa_dma->sg_dma, GFP_KERNEL);
 	if (!pxa_dma->sg_cpu)
 		return -ENOMEM;
 
 	pxa_dma->sglen = sglen;
+	offset = *sg_first_ofs;
 
-	for (i = 0; i < sglen; i++) {
-		int sg_i = sg_start + i;
-		struct scatterlist *sg = dma->sglist;
-		unsigned int dma_len = sg_dma_len(&sg[sg_i]), xfer_len;
+	dev_dbg(pcdev->dev, "DMA: sg_first=%p, sglen=%d, ofs=%d, dma.desc=%x\n",
+		*sg_first, sglen, *sg_first_ofs, pxa_dma->sg_dma);
 
-		pxa_dma->sg_cpu[i].dsadr = pcdev->res->start + cibr;
-		pxa_dma->sg_cpu[i].dtadr = sg_dma_address(&sg[sg_i]);
+
+	for_each_sg(*sg_first, sg, sglen, i) {
+		dma_len = sg_dma_len(sg);
 
 		/* PXA27x Developer's Manual 27.4.4.1: round up to 8 bytes */
-		xfer_len = (min(dma_len, size) + 7) & ~7;
+		xfer_len = roundup(min(dma_len - offset, size), 8);
 
+		size = max(0, size - xfer_len);
+
+		pxa_dma->sg_cpu[i].dsadr = pcdev->res->start + cibr;
+		pxa_dma->sg_cpu[i].dtadr = sg_dma_address(sg) + offset;
 		pxa_dma->sg_cpu[i].dcmd =
 			DCMD_FLOWSRC | DCMD_BURST8 | DCMD_INCTRGADDR | xfer_len;
-		size -= dma_len;
 		pxa_dma->sg_cpu[i].ddadr =
 			pxa_dma->sg_dma + (i + 1) * sizeof(struct pxa_dma_desc);
+
+		dev_vdbg(pcdev->dev, "DMA: desc.%08x->@phys=0x%08x, len=%d\n",
+			 pxa_dma->sg_dma + i * sizeof(struct pxa_dma_desc),
+			 sg_dma_address(sg) + offset, xfer_len);
+		offset = 0;
+
+		if (size == 0)
+			break;
 	}
 
 	pxa_dma->sg_cpu[sglen - 1].ddadr = DDADR_STOP;
 	pxa_dma->sg_cpu[sglen - 1].dcmd |= DCMD_ENDIRQEN;
 
+	/*
+	 * Handle 1 special case :
+	 *  - in 3 planes (YUV422P format), we might finish with xfer_len equal
+	 *    to dma_len (end on PAGE boundary). In this case, the sg element
+	 *    for next plane should be the next after the last used to store the
+	 *    last scatter gather RAM page
+	 */
+	if (xfer_len >= dma_len) {
+		*sg_first_ofs = xfer_len - dma_len;
+		*sg_first = sg_next(sg);
+	} else {
+		*sg_first_ofs = xfer_len;
+		*sg_first = sg;
+	}
+
 	return 0;
 }
 
@@ -340,7 +410,6 @@ static int pxa_videobuf_prepare(struct videobuf_queue *vq,
 	struct pxa_camera_dev *pcdev = ici->priv;
 	struct pxa_buffer *buf = container_of(vb, struct pxa_buffer, vb);
 	int ret;
-	int sglen_y,  sglen_yu = 0, sglen_u = 0, sglen_v = 0;
 	int size_y, size_u = 0, size_v = 0;
 
 	dev_dbg(&icd->dev, "%s (vb=0x%p) 0x%08lx %d\n", __func__,
@@ -379,53 +448,51 @@ static int pxa_videobuf_prepare(struct videobuf_queue *vq,
 	}
 
 	if (vb->state == VIDEOBUF_NEEDS_INIT) {
-		unsigned int size = vb->size;
+		int size = vb->size;
+		int next_ofs = 0;
 		struct videobuf_dmabuf *dma = videobuf_to_dma(vb);
+		struct scatterlist *sg;
 
 		ret = videobuf_iolock(vq, vb, NULL);
 		if (ret)
 			goto fail;
 
 		if (pcdev->channels == 3) {
-			/* FIXME the calculations should be more precise */
-			sglen_y = dma->sglen / 2;
-			sglen_u = sglen_v = dma->sglen / 4 + 1;
-			sglen_yu = sglen_y + sglen_u;
 			size_y = size / 2;
 			size_u = size_v = size / 4;
 		} else {
-			sglen_y = dma->sglen;
 			size_y = size;
 		}
 
-		/* init DMA for Y channel */
-		ret = pxa_init_dma_channel(pcdev, buf, dma, 0, sglen_y,
-					   0, 0x28, size_y);
+		sg = dma->sglist;
 
+		/* init DMA for Y channel */
+		ret = pxa_init_dma_channel(pcdev, buf, dma, 0, CIBR0, size_y,
+					   &sg, &next_ofs);
 		if (ret) {
 			dev_err(pcdev->dev,
 				"DMA initialization for Y/RGB failed\n");
 			goto fail;
 		}
 
-		if (pcdev->channels == 3) {
-			/* init DMA for U channel */
-			ret = pxa_init_dma_channel(pcdev, buf, dma, 1, sglen_u,
-						   sglen_y, 0x30, size_u);
-			if (ret) {
-				dev_err(pcdev->dev,
-					"DMA initialization for U failed\n");
-				goto fail_u;
-			}
+		/* init DMA for U channel */
+		if (size_u)
+			ret = pxa_init_dma_channel(pcdev, buf, dma, 1, CIBR1,
+						   size_u, &sg, &next_ofs);
+		if (ret) {
+			dev_err(pcdev->dev,
+				"DMA initialization for U failed\n");
+			goto fail_u;
+		}
 
-			/* init DMA for V channel */
-			ret = pxa_init_dma_channel(pcdev, buf, dma, 2, sglen_v,
-						   sglen_yu, 0x38, size_v);
-			if (ret) {
-				dev_err(pcdev->dev,
-					"DMA initialization for V failed\n");
-				goto fail_v;
-			}
+		/* init DMA for V channel */
+		if (size_v)
+			ret = pxa_init_dma_channel(pcdev, buf, dma, 2, CIBR2,
+						   size_v, &sg, &next_ofs);
+		if (ret) {
+			dev_err(pcdev->dev,
+				"DMA initialization for V failed\n");
+			goto fail_v;
 		}
 
 		vb->state = VIDEOBUF_PREPARED;