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media: hantro: jpeg: Add COM segment to JPEG header to align image scan

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The JPEG header size is not 64-bit aligned. This makes the driver
require a bounce buffer for the encoded JPEG image scan output.

Add a COM (comment) segment to the JPEG header so that the header size
is a multiple of 64 bits. This will then allow dropping the use of the
bounce buffer, and instead have the hardware write out to the capture
buffer directly.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
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>
This commit is contained in:
Chen-Yu Tsai
2022-01-07 10:34:52 +01:00
committed by Mauro Carvalho Chehab
parent e90410d130
commit 00b5359bac
2 changed files with 23 additions and 2 deletions
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23
drivers/staging/media/hantro/hantro_jpeg.c
View File

@@ -6,6 +6,9 @@
* Copyright (C) Jean-Francois Moine (http://moinejf.free.fr)
* Copyright (C) 2014 Philipp Zabel, Pengutronix
*/
#include <linux/align.h>
#include <linux/build_bug.h>
#include <linux/dma-mapping.h>
#include <linux/kernel.h>
#include <linux/string.h>
@@ -140,7 +143,7 @@ static const unsigned char chroma_ac_table[] = {
* and we'll use fixed offsets to change the width, height
* quantization tables, etc.
*/
static const unsigned char hantro_jpeg_header[JPEG_HEADER_SIZE] = {
static const unsigned char hantro_jpeg_header[] = {
/* SOI */
0xff, 0xd8,
@@ -247,11 +250,29 @@ static const unsigned char hantro_jpeg_header[JPEG_HEADER_SIZE] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
/* COM */
0xff, 0xfe, 0x00, 0x03, 0x00,
/* SOS */
0xff, 0xda, 0x00, 0x0c, 0x03, 0x01, 0x00, 0x02,
0x11, 0x03, 0x11, 0x00, 0x3f, 0x00,
};
/*
* JPEG_HEADER_SIZE is used in other parts of the driver in lieu of
* "sizeof(hantro_jpeg_header)". The two must be equal.
*/
static_assert(sizeof(hantro_jpeg_header) == JPEG_HEADER_SIZE);
/*
* hantro_jpeg_header is padded with a COM segment, so that the payload
* of the SOS segment (the entropy-encoded image scan), which should
* trail the whole header, is 8-byte aligned for the hardware to write
* to directly.
*/
static_assert(IS_ALIGNED(sizeof(hantro_jpeg_header), 8),
"Hantro JPEG header size needs to be 8-byte aligned.");
static unsigned char jpeg_scale_qp(const unsigned char qp, int scale)
{
unsigned int temp;

2
drivers/staging/media/hantro/hantro_jpeg.h
View File

@@ -1,6 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0+ */
#define JPEG_HEADER_SIZE 619
#define JPEG_HEADER_SIZE 624
#define JPEG_QUANT_SIZE 64
struct hantro_jpeg_ctx {