[PATCH 1/2] media: cedrus: Fix decoding for some HEVC videos

[Jernej Skrabec]

It seems that for some HEVC 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 several videos
with this fix are now decoded correctly and there is no regression with
others.

Without this fix, those same videos totally crash HEVC decoder (other
decoder engines are unaffected). After decoding those problematic
videos, HEVC decoder always returns only green image (all zeros).
Only complete HW reset helps.

This fix is similar to that for H264.

Signed-off-by: Jernej Skrabec <jernej.skrabec@xxxxxxxx>
---
 .../staging/media/sunxi/cedrus/cedrus_h265.c  | 25 ++++++++++++++++---
 .../staging/media/sunxi/cedrus/cedrus_regs.h  |  1 +
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
index 109d3289418c..5a207f1e137c 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
@@ -7,6 +7,7 @@
  * Copyright (C) 2018 Bootlin
  */
 
+#include <linux/delay.h>
 #include <linux/types.h>
 
 #include <media/videobuf2-dma-contig.h>
@@ -283,6 +284,23 @@ static void cedrus_h265_write_scaling_list(struct cedrus_ctx *ctx,
 		}
 }
 
+static void cedrus_h265_skip_bits(struct cedrus_dev *dev, int num)
+{
+	int count = 0;
+
+	while (count < num) {
+		int tmp = min(num - count, 32);
+
+		cedrus_write(dev, VE_DEC_H265_TRIGGER,
+			     VE_DEC_H265_TRIGGER_FLUSH_BITS |
+			     VE_DEC_H265_TRIGGER_TYPE_N_BITS(tmp));
+		while (cedrus_read(dev, VE_DEC_H265_STATUS) & VE_DEC_H265_STATUS_VLD_BUSY)
+			udelay(1);
+
+		count += tmp;
+	}
+}
+
 static void cedrus_h265_setup(struct cedrus_ctx *ctx,
 			      struct cedrus_run *run)
 {
@@ -347,10 +365,9 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
 
 	/* Source offset and length in bits. */
 
-	reg = slice_params->data_bit_offset;
-	cedrus_write(dev, VE_DEC_H265_BITS_OFFSET, reg);
+	cedrus_write(dev, VE_DEC_H265_BITS_OFFSET, 0);
 
-	reg = slice_params->bit_size - slice_params->data_bit_offset;
+	reg = slice_params->bit_size;
 	cedrus_write(dev, VE_DEC_H265_BITS_LEN, reg);
 
 	/* Source beginning and end addresses. */
@@ -385,6 +402,8 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
 	/* Initialize bitstream access. */
 	cedrus_write(dev, VE_DEC_H265_TRIGGER, VE_DEC_H265_TRIGGER_INIT_SWDEC);
 
+	cedrus_h265_skip_bits(dev, slice_params->data_bit_offset);
+
 	/* Bitstream parameters. */
 
 	reg = VE_DEC_H265_DEC_NAL_HDR_NAL_UNIT_TYPE(slice_params->nal_unit_type) |
diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_regs.h b/drivers/staging/media/sunxi/cedrus/cedrus_regs.h
index 0d9449fe2b28..df1cceef8d93 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_regs.h
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_regs.h
@@ -424,6 +424,7 @@
 
 #define VE_DEC_H265_TRIGGER			(VE_ENGINE_DEC_H265 + 0x34)
 
+#define VE_DEC_H265_TRIGGER_TYPE_N_BITS(x)	(((x) & 0x3f) << 8)
 #define VE_DEC_H265_TRIGGER_STCD_VC1		(0x02 << 4)
 #define VE_DEC_H265_TRIGGER_STCD_AVS		(0x01 << 4)
 #define VE_DEC_H265_TRIGGER_STCD_HEVC		(0x00 << 4)
-- 
2.24.0