linux-kernel - [PATCH 3/7] media: cedrus: Fix decoding for some H264 videos

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Date:   Thu, 30 May 2019 23:15:12 +0200
From:   Jernej Skrabec <jernej.skrabec@...l.net>
To:     paul.kocialkowski@...tlin.com, maxime.ripard@...tlin.com
Cc:     wens@...e.org, mchehab@...nel.org, gregkh@...uxfoundation.org,
        linux-media@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/7] media: cedrus: Fix decoding for some H264 videos

It seems that for some H264 videos at least one bitstream parsing
trigger must be called in order to be decoded correctly. There is no
explanation why this helps, but it was observed that two sample videos
with this fix are now decoded correctly and there is no regression with
others.

Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
---
I have two samples which are fixed by this:
http://jernej.libreelec.tv/videos/h264/test.mkv
http://jernej.libreelec.tv/videos/h264/Dredd%20%E2%80%93%20DTS%20Sound%20Check%20DTS-HD%20MA%207.1.m2ts

Although second one also needs support for multi-slice frames, which is not yet implemented here.

 .../staging/media/sunxi/cedrus/cedrus_h264.c  | 22 ++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
index cc8d17f211a1..d0ee3f90ff46 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
@@ -6,6 +6,7 @@
  * Copyright (c) 2018 Bootlin
  */
 
+#include <linux/delay.h>
 #include <linux/types.h>
 
 #include <media/videobuf2-dma-contig.h>
@@ -289,6 +290,20 @@ static void cedrus_write_pred_weight_table(struct cedrus_ctx *ctx,
 	}
 }
 
+static void cedrus_skip_bits(struct cedrus_dev *dev, int num)
+{
+	for (; num > 32; num -= 32) {
+		cedrus_write(dev, VE_H264_TRIGGER_TYPE, 0x3 | (32 << 8));
+		while (cedrus_read(dev, VE_H264_STATUS) & (1 << 8))
+			udelay(1);
+	}
+	if (num > 0) {
+		cedrus_write(dev, VE_H264_TRIGGER_TYPE, 0x3 | (num << 8));
+		while (cedrus_read(dev, VE_H264_STATUS) & (1 << 8))
+			udelay(1);
+	}
+}
+
 static void cedrus_set_params(struct cedrus_ctx *ctx,
 			      struct cedrus_run *run)
 {
@@ -299,12 +314,11 @@ static void cedrus_set_params(struct cedrus_ctx *ctx,
 	struct vb2_buffer *src_buf = &run->src->vb2_buf;
 	struct cedrus_dev *dev = ctx->dev;
 	dma_addr_t src_buf_addr;
-	u32 offset = slice->header_bit_size;
-	u32 len = (slice->size * 8) - offset;
+	u32 len = slice->size * 8;
 	u32 reg;
 
 	cedrus_write(dev, VE_H264_VLD_LEN, len);
-	cedrus_write(dev, VE_H264_VLD_OFFSET, offset);
+	cedrus_write(dev, VE_H264_VLD_OFFSET, 0);
 
 	src_buf_addr = vb2_dma_contig_plane_dma_addr(src_buf, 0);
 	cedrus_write(dev, VE_H264_VLD_END,
@@ -323,6 +337,8 @@ static void cedrus_set_params(struct cedrus_ctx *ctx,
 	cedrus_write(dev, VE_H264_TRIGGER_TYPE,
 		     VE_H264_TRIGGER_TYPE_INIT_SWDEC);
 
+	cedrus_skip_bits(dev, slice->header_bit_size);
+
 	if (((pps->flags & V4L2_H264_PPS_FLAG_WEIGHTED_PRED) &&
 	     (slice->slice_type == V4L2_H264_SLICE_TYPE_P ||
 	      slice->slice_type == V4L2_H264_SLICE_TYPE_SP)) ||
-- 
2.21.0