linux-kernel - [PATCH 2/7] media: cedrus: Fix H264 default reference index count

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Date:   Thu, 30 May 2019 23:15:11 +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,
        nicolas@...fresne.ca, boris.brezillon@...labora.com,
        jonas@...boo.se
Subject: [PATCH 2/7] media: cedrus: Fix H264 default reference index count

Reference index count in VE_H264_PPS reg should come from PPS control.
However, this is not really important because reference index count is
in our case always overridden by that from slice header.

Cc: nicolas@...fresne.ca
Cc: boris.brezillon@...labora.com
Cc: jonas@...boo.se

Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
---
We have to decide if we drop pps->num_ref_idx_l0_default_active_minus1
and pps->num_ref_idx_l1_default_active_minus1 fields or add
num_ref_idx_l0_active_override_flag and num_ref_idx_l0_active_override_flag
to slice control.

Current control doesn't have those two flags, so in Cedrus override flag is
always set and we rely on userspace to set slice->num_ref_idx_l0_active_minus1
and slice->num_ref_idx_l1_active_minus1 to correct values. This means that
values stored in PPS are not needed and always ignored by VPU.

If I understand correctly, algorithm is very simple:

ref_count = PPS->ref_count
if (override_flag)
	ref_count = slice->ref_count

It seems that VAAPI provides only final value. In my opinion we should do the
same - get rid of PPS default ref index count fields.

 drivers/staging/media/sunxi/cedrus/cedrus_h264.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
index a30bb283f69f..cc8d17f211a1 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
@@ -340,12 +340,8 @@ static void cedrus_set_params(struct cedrus_ctx *ctx,
 
 	// picture parameters
 	reg = 0;
-	/*
-	 * FIXME: the kernel headers are allowing the default value to
-	 * be passed, but the libva doesn't give us that.
-	 */
-	reg |= (slice->num_ref_idx_l0_active_minus1 & 0x1f) << 10;
-	reg |= (slice->num_ref_idx_l1_active_minus1 & 0x1f) << 5;
+	reg |= (pps->num_ref_idx_l0_default_active_minus1 & 0x1f) << 10;
+	reg |= (pps->num_ref_idx_l1_default_active_minus1 & 0x1f) << 5;
 	reg |= (pps->weighted_bipred_idc & 0x3) << 2;
 	if (pps->flags & V4L2_H264_PPS_FLAG_ENTROPY_CODING_MODE)
 		reg |= VE_H264_PPS_ENTROPY_CODING_MODE;
-- 
2.21.0