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Date:   Tue, 29 Mar 2022 14:57:16 +0200
From:   Sebastian Fricke <sebastian.fricke@collabora.com>
To:     Nicolas Dufresne <nicolas.dufresne@collabora.com>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>, kernel@collabora.com,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 05/24] media: h264: Store all fields into the
 unordered list
Message-ID: <20220329125716.qsuu24x5y4ezk2ob@basti-XPS-13-9310>
References: <20220328195936.82552-1-nicolas.dufresne@collabora.com>
 <20220328195936.82552-6-nicolas.dufresne@collabora.com>
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In-Reply-To: <20220328195936.82552-6-nicolas.dufresne@collabora.com>
Precedence: bulk

Hey Nicolas,

On 28.03.2022 15:59, Nicolas Dufresne wrote:
>When the current picture is a field, store each field into the
>unordered_list. Doing this required preserving the top and bottom field
>poc.

I would slightly reword this to highlight that we talk about the
reference list and to improve the grammatic of the second sentence:

"""
If the current image is a field, each field is stored in the unordered
reference list, preserving the original picture order count of the
top and bottom fields.
"""

>
>Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>

>---
> drivers/media/v4l2-core/v4l2-h264.c | 65 +++++++++++++++++++++--------
> include/media/v4l2-h264.h           |  6 ++-
> 2 files changed, 51 insertions(+), 20 deletions(-)
>
>diff --git a/drivers/media/v4l2-core/v4l2-h264.c b/drivers/media/v4l2-core/v4l2-h264.c
>index 4c6bfb057bda..d5698c981973 100644
>--- a/drivers/media/v4l2-core/v4l2-h264.c
>+++ b/drivers/media/v4l2-core/v4l2-h264.c
>@@ -47,8 +47,6 @@ v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
> 	}
>
> 	for (i = 0; i < V4L2_H264_NUM_DPB_ENTRIES; i++) {
>-		u32 pic_order_count;
>-
> 		if (!(dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
> 			continue;
>
>@@ -59,8 +57,6 @@ v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
> 		/*
> 		 * Handle frame_num wraparound as described in section
> 		 * '8.2.4.1 Decoding process for picture numbers' of the spec.
>-		 * TODO: This logic will have to be adjusted when we start
>-		 * supporting interlaced content.

Ah, I see here you remove the TODO comment disregard my comment from
patch 3 please.

Greetings,
Sebastian

> 		 * For long term reference, frame_num is set to
> 		 * long_term_frame_idx which requires no wrapping.
> 		 */
>@@ -70,17 +66,33 @@ v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
> 		else
> 			b->refs[i].frame_num = dpb[i].frame_num;
>
>-		if (dpb[i].fields == V4L2_H264_FRAME_REF)
>-			pic_order_count = min(dpb[i].top_field_order_cnt,
>-					      dpb[i].bottom_field_order_cnt);
>-		else if (dpb[i].fields & V4L2_H264_BOTTOM_FIELD_REF)
>-			pic_order_count = dpb[i].bottom_field_order_cnt;
>-		else
>-			pic_order_count = dpb[i].top_field_order_cnt;
>+		b->refs[i].top_field_order_cnt = dpb[i].top_field_order_cnt;
>+		b->refs[i].bottom_field_order_cnt = dpb[i].bottom_field_order_cnt;
>+
>+		if (b->cur_pic_fields == V4L2_H264_FRAME_REF) {
>+			u8 fields = V4L2_H264_FRAME_REF;
>+
>+			b->unordered_reflist[b->num_valid].index = i;
>+			b->unordered_reflist[b->num_valid].fields = fields;

>+			b->num_valid++;
>+			continue;
>+		}
>+
>+		if (dpb[i].fields & V4L2_H264_TOP_FIELD_REF) {
>+			u8 fields = V4L2_H264_TOP_FIELD_REF;
>+
>+			b->unordered_reflist[b->num_valid].index = i;
>+			b->unordered_reflist[b->num_valid].fields = fields;
>+			b->num_valid++;
>+		}
>
>-		b->refs[i].pic_order_count = pic_order_count;
>-		b->unordered_reflist[b->num_valid].index = i;
>-		b->num_valid++;
>+		if (dpb[i].fields & V4L2_H264_BOTTOM_FIELD_REF) {
>+			u8 fields = V4L2_H264_BOTTOM_FIELD_REF;
>+
>+			b->unordered_reflist[b->num_valid].index = i;
>+			b->unordered_reflist[b->num_valid].fields = fields;
>+			b->num_valid++;
>+		}
> 	}
>
> 	for (i = b->num_valid; i < ARRAY_SIZE(b->unordered_reflist); i++)
>@@ -88,6 +100,23 @@ v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
> }
> EXPORT_SYMBOL_GPL(v4l2_h264_init_reflist_builder);
>
>+static s32 v4l2_h264_get_poc(const struct v4l2_h264_reflist_builder *b,
>+			     const struct v4l2_h264_reference *ref)
>+{
>+	switch (ref->fields) {
>+	case V4L2_H264_FRAME_REF:
>+		return min(b->refs[ref->index].top_field_order_cnt,
>+				b->refs[ref->index].bottom_field_order_cnt);
>+	case V4L2_H264_TOP_FIELD_REF:
>+		return b->refs[ref->index].top_field_order_cnt;
>+	case V4L2_H264_BOTTOM_FIELD_REF:
>+		return b->refs[ref->index].bottom_field_order_cnt;
>+	}
>+
>+	/* not reached */
>+	return 0;
>+}
>+
> static int v4l2_h264_p_ref_list_cmp(const void *ptra, const void *ptrb,
> 				    const void *data)
> {
>@@ -150,8 +179,8 @@ static int v4l2_h264_b0_ref_list_cmp(const void *ptra, const void *ptrb,
> 		       builder->refs[idxb].pic_num ?
> 		       -1 : 1;
>
>-	poca = builder->refs[idxa].pic_order_count;
>-	pocb = builder->refs[idxb].pic_order_count;
>+	poca = v4l2_h264_get_poc(builder, ptra);
>+	pocb = v4l2_h264_get_poc(builder, ptrb);
>
> 	/*
> 	 * Short term pics with POC < cur POC first in POC descending order
>@@ -195,8 +224,8 @@ static int v4l2_h264_b1_ref_list_cmp(const void *ptra, const void *ptrb,
> 		       builder->refs[idxb].pic_num ?
> 		       -1 : 1;
>
>-	poca = builder->refs[idxa].pic_order_count;
>-	pocb = builder->refs[idxb].pic_order_count;
>+	poca = v4l2_h264_get_poc(builder, ptra);
>+	pocb = v4l2_h264_get_poc(builder, ptrb);
>
> 	/*
> 	 * Short term pics with POC > cur POC first in POC ascending order
>diff --git a/include/media/v4l2-h264.h b/include/media/v4l2-h264.h
>index e165a54c68fa..4cef717b3f18 100644
>--- a/include/media/v4l2-h264.h
>+++ b/include/media/v4l2-h264.h
>@@ -15,7 +15,8 @@
> /**
>  * struct v4l2_h264_reflist_builder - Reference list builder object
>  *
>- * @refs.pic_order_count: reference picture order count
>+ * @refs.top_field_order_cnt: top field order count
>+ * @refs.bottom_field_order_cnt: bottom field order count
>  * @refs.frame_num: reference frame number
>  * @refs.pic_num: reference picture number
>  * @refs.longterm: set to true for a long term reference
>@@ -32,7 +33,8 @@
>  */
> struct v4l2_h264_reflist_builder {
> 	struct {
>-		s32 pic_order_count;
>+		s32 top_field_order_cnt;
>+		s32 bottom_field_order_cnt;
> 		int frame_num;
> 		u32 pic_num;
> 		u16 longterm : 1;
>-- 
>2.34.1
>