[PATCH 2/2] media: cedrus: h265: Fix logic for not low delay flag

[Jernej Skrabec]

Now that we know real purpose of "not low delay" flag, logic for
applying this flag should be fixed too. According to vendor and
reference implementation, low delay is signaled when POC of current
frame is lower than POC of at least one reference of a slice.

Implement mentioned logic and invert it to conform to flag meaning. Also
don't apply flag for I frames. They don't have any reference.

This fixes decoding of 3 reference bitstreams.

Fixes: 86caab29da78 ("media: cedrus: Add HEVC/H.265 decoding support")
Signed-off-by: Jernej Skrabec <jernej.skrabec at gmail.com>
---
 .../staging/media/sunxi/cedrus/cedrus_h265.c  | 27 ++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
index 2febdf7a97fe..3f50043093be 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
@@ -301,6 +301,31 @@ static void cedrus_h265_write_scaling_list(struct cedrus_ctx *ctx,
 		}
 }
 
+static int cedrus_h265_is_low_delay(struct cedrus_run *run)
+{
+	const struct v4l2_ctrl_hevc_slice_params *slice_params;
+	const struct v4l2_hevc_dpb_entry *dpb;
+	s32 poc;
+	int i;
+
+	slice_params = run->h265.slice_params;
+	poc = run->h265.decode_params->pic_order_cnt_val;
+	dpb = run->h265.decode_params->dpb;
+
+	for (i = 0; i < slice_params->num_ref_idx_l0_active_minus1 + 1; i++)
+		if (dpb[slice_params->ref_idx_l0[i]].pic_order_cnt[0] > poc)
+			return 1;
+
+	if (slice_params->slice_type != V4L2_HEVC_SLICE_TYPE_B)
+		return 0;
+
+	for (i = 0; i < slice_params->num_ref_idx_l1_active_minus1 + 1; i++)
+		if (dpb[slice_params->ref_idx_l1[i]].pic_order_cnt[0] > poc)
+			return 1;
+
+	return 0;
+}
+
 static void cedrus_h265_setup(struct cedrus_ctx *ctx,
 			      struct cedrus_run *run)
 {
@@ -571,7 +596,7 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
 				V4L2_HEVC_SLICE_PARAMS_FLAG_SLICE_LOOP_FILTER_ACROSS_SLICES_ENABLED,
 				slice_params->flags);
 
-	if (decode_params->num_poc_st_curr_after == 0)
+	if (slice_params->slice_type != V4L2_HEVC_SLICE_TYPE_I && !cedrus_h265_is_low_delay(run))
 		reg |= VE_DEC_H265_DEC_SLICE_HDR_INFO1_FLAG_SLICE_NOT_LOW_DELAY;
 
 	cedrus_write(dev, VE_DEC_H265_DEC_SLICE_HDR_INFO1, reg);
-- 
2.36.1