[media] coda: pad first h.264 buffer to 512 bytes

The bitstream reader needs 512 bytes ready to read to examine the
headers in the first frame. If that frame is too small, prepend it
with a filler NAL.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 26 insertions, 2 deletions

diff --git a/drivers/media/platform/coda/coda-bit.c b/drivers/media/platform/coda/coda-bit.c
index e3e322560783..89965ca5bd25 100644
--- a/drivers/media/platform/coda/coda-bit.c
+++ b/drivers/media/platform/coda/coda-bit.c
@@ -179,6 +179,25 @@ static void coda_kfifo_sync_to_device_write(struct coda_ctx *ctx)
 	coda_write(dev, wr_ptr, CODA_REG_BIT_WR_PTR(ctx->reg_idx));
 }
 
+static int coda_bitstream_pad(struct coda_ctx *ctx, u32 size)
+{
+	unsigned char *buf;
+	u32 n;
+
+	if (size < 6)
+		size = 6;
+
+	buf = kmalloc(size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	coda_h264_filler_nal(size, buf);
+	n = kfifo_in(&ctx->bitstream_fifo, buf, size);
+	kfree(buf);
+
+	return (n < size) ? -ENOSPC : 0;
+}
+
 static int coda_bitstream_queue(struct coda_ctx *ctx,
 				struct vb2_v4l2_buffer *src_buf)
 {
@@ -198,10 +217,10 @@ static int coda_bitstream_queue(struct coda_ctx *ctx,
 static bool coda_bitstream_try_queue(struct coda_ctx *ctx,
 				     struct vb2_v4l2_buffer *src_buf)
 {
+	unsigned long payload = vb2_get_plane_payload(&src_buf->vb2_buf, 0);
 	int ret;
 
-	if (coda_get_bitstream_payload(ctx) +
-	    vb2_get_plane_payload(&src_buf->vb2_buf, 0) + 512 >=
+	if (coda_get_bitstream_payload(ctx) + payload + 512 >=
 	    ctx->bitstream.size)
 		return false;
 
@@ -210,6 +229,11 @@ static bool coda_bitstream_try_queue(struct coda_ctx *ctx,
 		return true;
 	}
 
+	/* Add zero padding before the first H.264 buffer, if it is too small */
+	if (ctx->qsequence == 0 && payload < 512 &&
+	    ctx->codec->src_fourcc == V4L2_PIX_FMT_H264)
+		coda_bitstream_pad(ctx, 512 - payload);
+
 	ret = coda_bitstream_queue(ctx, src_buf);
 	if (ret < 0) {
 		v4l2_err(&ctx->dev->v4l2_dev, "bitstream buffer overflow\n");