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Message-ID: <0aef6cd5cc7019912a973ad8c5ba5e7b6105baf9.camel@collabora.com>
Subject: Re: [PATCH] media: rkvdec: Fix H264 scaling list order
From:   Ezequiel Garcia <ezequiel@collabora.com>
To:     Jonas Karlman <jonas@kwiboo.se>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Mauro Carvalho Chehab <mchehab@kernel.org>
Cc:     Jeffrey Kardatzke <jkardatzke@chromium.org>,
        Alexandre Courbot <acourbot@chromium.org>,
        Boris Brezillon <boris.brezillon@collabora.com>,
        Tomasz Figa <tfiga@chromium.org>,
        Nicolas Dufresne <nicolas.dufresne@collabora.com>,
        linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org,
        linux-kernel@vger.kernel.org
Date:   Tue, 02 Jun 2020 01:36:37 -0300
In-Reply-To: <20200522202130.13306-1-jonas@kwiboo.se>
References: <20200522202130.13306-1-jonas@kwiboo.se>
Organization: Collabora
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Hi Jonas,

Thanks a lot for the fix! Indeed it fixes
a few bitstream that had artifacts :)

On Fri, 2020-05-22 at 20:21 +0000, Jonas Karlman wrote:
> The Rockchip Video Decoder driver is expecting that the values in a
> scaling list are in zig-zag order and applies the inverse scanning process
> to get the values in matrix order.
> 
> Commit 0b0393d59eb4 ("media: uapi: h264: clarify expected
> scaling_list_4x4/8x8 order") clarified that the values in the scaling list
> should already be in matrix order.
> 
> Fix this by removing the reordering and change to use two memcpy.
> 
> Fixes: cd33c830448b ("media: rkvdec: Add the rkvdec driver")
> Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
> ---
>  drivers/staging/media/rkvdec/rkvdec-h264.c | 70 +++++++---------------
>  1 file changed, 22 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/staging/media/rkvdec/rkvdec-h264.c b/drivers/staging/media/rkvdec/rkvdec-h264.c
> index cd4980d06be7..2719f0c66a4a 100644
> --- a/drivers/staging/media/rkvdec/rkvdec-h264.c
> +++ b/drivers/staging/media/rkvdec/rkvdec-h264.c
> @@ -18,11 +18,16 @@
>  /* Size with u32 units. */
>  #define RKV_CABAC_INIT_BUFFER_SIZE	(3680 + 128)
>  #define RKV_RPS_SIZE			((128 + 128) / 4)
> -#define RKV_SCALING_LIST_SIZE		(6 * 16 + 6 * 64 + 128)
>  #define RKV_ERROR_INFO_SIZE		(256 * 144 * 4)
>  
>  #define RKVDEC_NUM_REFLIST		3
>  
> +struct rkvdec_scaling_matrix {

How about we call this rkvdec_scaling_list
or even rkvdec_h264_scaling_list?

It'll make code more readable and easier to grep.

> +	u8 scaling_list_4x4[6][16];
> +	u8 scaling_list_8x8[6][64];
> +	u8 padding[128];

Oops, something is wrong here, maybe some
mistake when porting code around.

Rockchip MPP defines the scaling list size as:

#define RKV_SCALING_LIST_SIZE (6*16 + 2*64 + 128)

Consistently with the fact that 4:4:4 sampling
is not supported (chroma_format_idc == 3),
only the first two scaling matrices are used.

Moreover, given all these buffers are specified separately
(see below), I bet not even the 128 padding bytes
are needed.
 
> +};
> +
>  struct rkvdec_sps_pps_packet {
>  	u32 info[8];
>  };
> @@ -86,7 +91,7 @@ struct rkvdec_ps_field {
>  /* Data structure describing auxiliary buffer format. */
>  struct rkvdec_h264_priv_tbl {
>  	s8 cabac_table[4][464][2];

As can be seen, all these buffers can be allocated
independently, which perhaps could reduce the
pressure on the DMA allocator.

> -	u8 scaling_list[RKV_SCALING_LIST_SIZE];
> +	struct rkvdec_scaling_matrix scaling_list;
>  	u32 rps[RKV_RPS_SIZE];
>  	struct rkvdec_sps_pps_packet param_set[256];
>  	u8 err_info[RKV_ERROR_INFO_SIZE];

In particular, I wonder if the error info stuff
is really required.

I guess we'll want to merge a simple fix,
so no need to address any of these questions
for now.

With the struct rkvdec_scaling_matrix rename:

Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>

Thanks,
Ezequiel

> @@ -785,56 +790,25 @@ static void assemble_hw_rps(struct rkvdec_ctx *ctx,
>  	}
>  }
>  
> -/*
> - * NOTE: The values in a scaling list are in zig-zag order, apply inverse
> - * scanning process to get the values in matrix order.
> - */
> -static const u32 zig_zag_4x4[16] = {
> -	0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
> -};
> -
> -static const u32 zig_zag_8x8[64] = {
> -	0,  1,  8, 16,  9,  2,  3, 10, 17, 24, 32, 25, 18, 11,  4,  5,
> -	12, 19, 26, 33, 40, 48, 41, 34, 27, 20, 13,  6,  7, 14, 21, 28,
> -	35, 42, 49, 56, 57, 50, 43, 36, 29, 22, 15, 23, 30, 37, 44, 51,
> -	58, 59, 52, 45, 38, 31, 39, 46, 53, 60, 61, 54, 47, 55, 62, 63
> -};
> -
> -static void reorder_scaling_list(struct rkvdec_ctx *ctx,
> -				 struct rkvdec_h264_run *run)
> +static void assemble_hw_scaling_list(struct rkvdec_ctx *ctx,
> +				     struct rkvdec_h264_run *run)
>  {
>  	const struct v4l2_ctrl_h264_scaling_matrix *scaling = run->scaling_matrix;
> -	const size_t num_list_4x4 = ARRAY_SIZE(scaling->scaling_list_4x4);
> -	const size_t list_len_4x4 = ARRAY_SIZE(scaling->scaling_list_4x4[0]);
> -	const size_t num_list_8x8 = ARRAY_SIZE(scaling->scaling_list_8x8);
> -	const size_t list_len_8x8 = ARRAY_SIZE(scaling->scaling_list_8x8[0]);
>  	struct rkvdec_h264_ctx *h264_ctx = ctx->priv;
>  	struct rkvdec_h264_priv_tbl *tbl = h264_ctx->priv_tbl.cpu;
> -	u8 *dst = tbl->scaling_list;
> -	const u8 *src;
> -	int i, j;
> -
> -	BUILD_BUG_ON(ARRAY_SIZE(zig_zag_4x4) != list_len_4x4);
> -	BUILD_BUG_ON(ARRAY_SIZE(zig_zag_8x8) != list_len_8x8);
> -	BUILD_BUG_ON(ARRAY_SIZE(tbl->scaling_list) <
> -		     num_list_4x4 * list_len_4x4 +
> -		     num_list_8x8 * list_len_8x8);
> -
> -	src = &scaling->scaling_list_4x4[0][0];
> -	for (i = 0; i < num_list_4x4; ++i) {
> -		for (j = 0; j < list_len_4x4; ++j)
> -			dst[zig_zag_4x4[j]] = src[j];
> -		src += list_len_4x4;
> -		dst += list_len_4x4;
> -	}
>  
> -	src = &scaling->scaling_list_8x8[0][0];
> -	for (i = 0; i < num_list_8x8; ++i) {
> -		for (j = 0; j < list_len_8x8; ++j)
> -			dst[zig_zag_8x8[j]] = src[j];
> -		src += list_len_8x8;
> -		dst += list_len_8x8;
> -	}
> +	BUILD_BUG_ON(sizeof(tbl->scaling_list.scaling_list_4x4) !=
> +		     sizeof(scaling->scaling_list_4x4));
> +	BUILD_BUG_ON(sizeof(tbl->scaling_list.scaling_list_8x8) !=
> +		     sizeof(scaling->scaling_list_8x8));
> +
> +	memcpy(tbl->scaling_list.scaling_list_4x4,
> +	       scaling->scaling_list_4x4,
> +	       sizeof(scaling->scaling_list_4x4));
> +
> +	memcpy(tbl->scaling_list.scaling_list_8x8,
> +	       scaling->scaling_list_8x8,
> +	       sizeof(scaling->scaling_list_8x8));
>  }
>  
>  /*
> @@ -1126,7 +1100,7 @@ static int rkvdec_h264_run(struct rkvdec_ctx *ctx)
>  	v4l2_h264_build_b_ref_lists(&reflist_builder, h264_ctx->reflists.b0,
>  				    h264_ctx->reflists.b1);
>  
> -	reorder_scaling_list(ctx, &run);
> +	assemble_hw_scaling_list(ctx, &run);
>  	assemble_hw_pps(ctx, &run);
>  	assemble_hw_rps(ctx, &run);
>  	config_registers(ctx, &run);