From: Chen-Yu Tsai <wenst@chromium.org>
To: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>,
Philipp Zabel <p.zabel@pengutronix.de>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Hans Verkuil <hverkuil-cisco@xs4all.nl>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Chen-Yu Tsai <wenst@chromium.org>,
linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org,
linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: [PATCH RFT v2 5/8] media: hantro: jpeg: Add COM segment to JPEG header to align image scan
Date: Fri, 7 Jan 2022 17:34:52 +0800 [thread overview]
Message-ID: <20220107093455.73766-6-wenst@chromium.org> (raw)
In-Reply-To: <20220107093455.73766-1-wenst@chromium.org>
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>
---
drivers/staging/media/hantro/hantro_jpeg.c | 23 +++++++++++++++++++++-
drivers/staging/media/hantro/hantro_jpeg.h | 2 +-
2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/media/hantro/hantro_jpeg.c b/drivers/staging/media/hantro/hantro_jpeg.c
index 7d4018bd6876..e63eeef3952d 100644
--- a/drivers/staging/media/hantro/hantro_jpeg.c
+++ b/drivers/staging/media/hantro/hantro_jpeg.c
@@ -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;
diff --git a/drivers/staging/media/hantro/hantro_jpeg.h b/drivers/staging/media/hantro/hantro_jpeg.h
index f33c492134e4..0b49d0b82caa 100644
--- a/drivers/staging/media/hantro/hantro_jpeg.h
+++ b/drivers/staging/media/hantro/hantro_jpeg.h
@@ -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 {
--
2.34.1.575.g55b058a8bb-goog
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next prev parent reply other threads:[~2022-01-07 9:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-07 9:34 [PATCH RFT v2 0/8] media: hantro: jpeg: Various improvements Chen-Yu Tsai
2022-01-07 9:34 ` [PATCH RFT v2 1/8] media: hantro: jpeg: Relax register writes before write starting hardware Chen-Yu Tsai
2022-01-18 21:02 ` Ezequiel Garcia
2022-01-19 10:08 ` Chen-Yu Tsai
2022-01-19 11:59 ` Ezequiel Garcia
2022-01-20 14:20 ` Hans Verkuil
2022-01-21 2:25 ` Chen-Yu Tsai
2022-01-07 9:34 ` [PATCH RFT v2 2/8] media: hantro: Fix overfill bottom register field name Chen-Yu Tsai
2022-01-07 9:34 ` [PATCH RFT v2 3/8] media: hantro: Support cropping visible area for encoders Chen-Yu Tsai
2022-01-07 9:34 ` [PATCH RFT v2 4/8] media: hantro: jpeg: Add JFIF APP0 segment to JPEG encoder output Chen-Yu Tsai
2022-01-07 9:34 ` Chen-Yu Tsai [this message]
2022-01-07 9:34 ` [PATCH RFT v2 6/8] media: hantro: Implement V4L2_CID_JPEG_ACTIVE_MARKER control Chen-Yu Tsai
2022-01-07 9:34 ` [PATCH RFT v2 7/8] media: hantro: output encoded JPEG content directly to capture buffers Chen-Yu Tsai
2022-01-07 9:34 ` [PATCH RFT v2 8/8] media: hantro: jpeg: Remove open-coded size in quantization table code Chen-Yu Tsai
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