media: hevc: Embedded indexes in RPS

Reference Picture Set lists provide indices of short and long term
reference in DBP array.
Fix Hantro to not do a look up in DBP entries.
Make documentation more clear about it.

[hverkuil: fix typo in commit log]
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst

@@ -3383,15 +3383,15 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
     * - __u8
       - ``poc_st_curr_before[V4L2_HEVC_DPB_ENTRIES_NUM_MAX]``
       - PocStCurrBefore as described in section 8.3.2 "Decoding process for reference
-        picture set.
+        picture set": provides the index of the short term before references in DPB array.
     * - __u8
       - ``poc_st_curr_after[V4L2_HEVC_DPB_ENTRIES_NUM_MAX]``
       - PocStCurrAfter as described in section 8.3.2 "Decoding process for reference
-        picture set.
+        picture set": provides the index of the short term after references in DPB array.
     * - __u8
       - ``poc_lt_curr[V4L2_HEVC_DPB_ENTRIES_NUM_MAX]``
       - PocLtCurr as described in section 8.3.2 "Decoding process for reference
-        picture set.
+        picture set": provides the index of the long term references in DPB array.
     * - __u64
       - ``flags``
       - See :ref:`Decode Parameters Flags <hevc_decode_params_flags>`

drivers/staging/media/hantro/hantro_g2_hevc_dec.c

@@ -255,24 +255,11 @@ static void set_params(struct hantro_ctx *ctx)
 	hantro_reg_write(vpu, &g2_apf_threshold, 8);
 }
 
-static int find_ref_pic_index(const struct v4l2_hevc_dpb_entry *dpb, int pic_order_cnt)
-{
-	int i;
-
-	for (i = 0; i < V4L2_HEVC_DPB_ENTRIES_NUM_MAX; i++) {
-		if (dpb[i].pic_order_cnt[0] == pic_order_cnt)
-			return i;
-	}
-
-	return 0x0;
-}
-
 static void set_ref_pic_list(struct hantro_ctx *ctx)
 {
 	const struct hantro_hevc_dec_ctrls *ctrls = &ctx->hevc_dec.ctrls;
 	struct hantro_dev *vpu = ctx->dev;
 	const struct v4l2_ctrl_hevc_decode_params *decode_params = ctrls->decode_params;
-	const struct v4l2_hevc_dpb_entry *dpb = decode_params->dpb;
 	u32 list0[V4L2_HEVC_DPB_ENTRIES_NUM_MAX] = {};
 	u32 list1[V4L2_HEVC_DPB_ENTRIES_NUM_MAX] = {};
 	static const struct hantro_reg ref_pic_regs0[] = {
@@ -316,11 +303,11 @@ static void set_ref_pic_list(struct hantro_ctx *ctx)
 	/* List 0 contains: short term before, short term after and long term */
 	j = 0;
 	for (i = 0; i < decode_params->num_poc_st_curr_before && j < ARRAY_SIZE(list0); i++)
-		list0[j++] = find_ref_pic_index(dpb, decode_params->poc_st_curr_before[i]);
+		list0[j++] = decode_params->poc_st_curr_before[i];
 	for (i = 0; i < decode_params->num_poc_st_curr_after && j < ARRAY_SIZE(list0); i++)
-		list0[j++] = find_ref_pic_index(dpb, decode_params->poc_st_curr_after[i]);
+		list0[j++] = decode_params->poc_st_curr_after[i];
 	for (i = 0; i < decode_params->num_poc_lt_curr && j < ARRAY_SIZE(list0); i++)
-		list0[j++] = find_ref_pic_index(dpb, decode_params->poc_lt_curr[i]);
+		list0[j++] = decode_params->poc_lt_curr[i];
 
 	/* Fill the list, copying over and over */
 	i = 0;
@@ -329,11 +316,11 @@ static void set_ref_pic_list(struct hantro_ctx *ctx)
 
 	j = 0;
 	for (i = 0; i < decode_params->num_poc_st_curr_after && j < ARRAY_SIZE(list1); i++)
-		list1[j++] = find_ref_pic_index(dpb, decode_params->poc_st_curr_after[i]);
+		list1[j++] = decode_params->poc_st_curr_after[i];
 	for (i = 0; i < decode_params->num_poc_st_curr_before && j < ARRAY_SIZE(list1); i++)
-		list1[j++] = find_ref_pic_index(dpb, decode_params->poc_st_curr_before[i]);
+		list1[j++] = decode_params->poc_st_curr_before[i];
 	for (i = 0; i < decode_params->num_poc_lt_curr && j < ARRAY_SIZE(list1); i++)
-		list1[j++] = find_ref_pic_index(dpb, decode_params->poc_lt_curr[i]);
+		list1[j++] = decode_params->poc_lt_curr[i];
 
 	i = 0;
 	while (j < ARRAY_SIZE(list1))