media: hantro: HEVC: Fix reference frames management

PoC shall be int the range of -2^31 to 2^31 -1
(HEVC spec section 8.3.1 Decoding process for picture order count).
The current way to know if an entry in reference picture array is free
is to test if PoC = UNUSED_REF. Since UNUSED_REF is defined as '-1' that
could lead to decode issue if one PoC also equal '-1'.
PoC with value = '-1' exists in conformance test SLIST_B_Sony_9.

Change the way unused entries are managed in reference pictures array to
avoid using PoC to detect then.

This patch doesn't change fluster HEVC score.
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>

drivers/staging/media/hantro/hantro_g2_hevc_dec.c

@@ -420,7 +420,7 @@ static int set_ref(struct hantro_ctx *ctx)
 	set_ref_pic_list(ctx);
 
 	/* We will only keep the reference pictures that are still used */
-	ctx->hevc_dec.ref_bufs_used = 0;
+	hantro_hevc_ref_init(ctx);
 
 	/* Set up addresses of DPB buffers */
 	dpb_longterm_e = 0;
@@ -461,8 +461,6 @@ static int set_ref(struct hantro_ctx *ctx)
 	hantro_write_addr(vpu, G2_OUT_CHROMA_ADDR, chroma_addr);
 	hantro_write_addr(vpu, G2_OUT_MV_ADDR, mv_addr);
 
-	hantro_hevc_ref_remove_unused(ctx);
-
 	for (; i < V4L2_HEVC_DPB_ENTRIES_NUM_MAX; i++) {
 		hantro_write_addr(vpu, G2_REF_LUMA_ADDR(i), 0);
 		hantro_write_addr(vpu, G2_REF_CHROMA_ADDR(i), 0);

drivers/staging/media/hantro/hantro_hevc.c

@@ -25,15 +25,11 @@
 #define MAX_TILE_COLS 20
 #define MAX_TILE_ROWS 22
 
-#define UNUSED_REF	-1
-
-static void hantro_hevc_ref_init(struct hantro_ctx *ctx)
+void hantro_hevc_ref_init(struct hantro_ctx *ctx)
 {
 	struct hantro_hevc_dec_hw_ctx *hevc_dec = &ctx->hevc_dec;
-	int i;
 
-	for (i = 0;  i < NUM_REF_PICTURES; i++)
-		hevc_dec->ref_bufs_poc[i] = UNUSED_REF;
+	hevc_dec->ref_bufs_used = 0;
 }
 
 dma_addr_t hantro_hevc_get_ref_buf(struct hantro_ctx *ctx,
@@ -60,7 +56,7 @@ int hantro_hevc_add_ref_buf(struct hantro_ctx *ctx, int poc, dma_addr_t addr)
 
 	/* Add a new reference buffer */
 	for (i = 0; i < NUM_REF_PICTURES; i++) {
-		if (hevc_dec->ref_bufs_poc[i] == UNUSED_REF) {
+		if (!(hevc_dec->ref_bufs_used & 1 << i)) {
 			hevc_dec->ref_bufs_used |= 1 << i;
 			hevc_dec->ref_bufs_poc[i] = poc;
 			hevc_dec->ref_bufs[i].dma = addr;
@@ -71,23 +67,6 @@ int hantro_hevc_add_ref_buf(struct hantro_ctx *ctx, int poc, dma_addr_t addr)
 	return -EINVAL;
 }
 
-void hantro_hevc_ref_remove_unused(struct hantro_ctx *ctx)
-{
-	struct hantro_hevc_dec_hw_ctx *hevc_dec = &ctx->hevc_dec;
-	int i;
-
-	/* Just tag buffer as unused, do not free them */
-	for (i = 0;  i < NUM_REF_PICTURES; i++) {
-		if (hevc_dec->ref_bufs_poc[i] == UNUSED_REF)
-			continue;
-
-		if (hevc_dec->ref_bufs_used & (1 << i))
-			continue;
-
-		hevc_dec->ref_bufs_poc[i] = UNUSED_REF;
-	}
-}
-
 static int tile_buffer_reallocate(struct hantro_ctx *ctx)
 {
 	struct hantro_dev *vpu = ctx->dev;

drivers/staging/media/hantro/hantro_hw.h

@@ -342,9 +342,9 @@ int hantro_hevc_dec_init(struct hantro_ctx *ctx);
 void hantro_hevc_dec_exit(struct hantro_ctx *ctx);
 int hantro_g2_hevc_dec_run(struct hantro_ctx *ctx);
 int hantro_hevc_dec_prepare_run(struct hantro_ctx *ctx);
+void hantro_hevc_ref_init(struct hantro_ctx *ctx);
 dma_addr_t hantro_hevc_get_ref_buf(struct hantro_ctx *ctx, int poc);
 int hantro_hevc_add_ref_buf(struct hantro_ctx *ctx, int poc, dma_addr_t addr);
-void hantro_hevc_ref_remove_unused(struct hantro_ctx *ctx);
 
 static inline unsigned short hantro_vp9_num_sbs(unsigned short dimension)
 {