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Subject: Re: [PATCH v2 2/2] media: platform: Add Aspeed Video Engine driver
To:     Eddie James <eajames@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org
Cc:     mark.rutland@arm.com, devicetree@vger.kernel.org,
        linux-aspeed@lists.ozlabs.org, openbmc@lists.ozlabs.org,
        robh+dt@kernel.org, mchehab@kernel.org,
        linux-media@vger.kernel.org, andrew@aj.id.au, joel@jms.id.au
References: <1536866964-71593-1-git-send-email-eajames@linux.vnet.ibm.com>
 <1536866964-71593-3-git-send-email-eajames@linux.vnet.ibm.com>
From:   Hans Verkuil <hverkuil@xs4all.nl>
Message-ID: <d1d58122-976b-b1dd-e4b4-bcc475219925@xs4all.nl>
Date:   Fri, 14 Sep 2018 10:19:19 +0200
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On 09/13/2018 09:29 PM, Eddie James wrote:
> The Video Engine (VE) embedded in the Aspeed AST2400 and AST2500 SOCs
> can capture and compress video data from digital or analog sources. With
> the Aspeed chip acting a service processor, the Video Engine can capture
> the host processor graphics output.
> 
> Add a V4L2 driver to capture video data and compress it to JPEG images,
> making the data available through a standard read interface.
> 
> Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
> ---
>  MAINTAINERS                           |    8 +
>  drivers/media/platform/Kconfig        |    8 +
>  drivers/media/platform/Makefile       |    1 +
>  drivers/media/platform/aspeed-video.c | 1469 +++++++++++++++++++++++++++++++++
>  4 files changed, 1486 insertions(+)
>  create mode 100644 drivers/media/platform/aspeed-video.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 389fb2e..d8352ad 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2356,6 +2356,14 @@ S:	Maintained
>  F:	Documentation/hwmon/asc7621
>  F:	drivers/hwmon/asc7621.c
>  
> +ASPEED VIDEO ENGINE DRIVER
> +M:	Eddie James <eajames@linux.vnet.ibm.com>
> +L:	linux-media@vger.kernel.org
> +L:	openbmc@lists.ozlabs.org (moderated for non-subscribers)
> +S:	Maintained
> +F:	drivers/media/platform/aspeed-video.c
> +F:	Documentation/devicetree/bindings/media/aspeed-video.txt
> +
>  ASUS NOTEBOOKS AND EEEPC ACPI/WMI EXTRAS DRIVERS
>  M:	Corentin Chary <corentin.chary@gmail.com>
>  L:	acpi4asus-user@lists.sourceforge.net
> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> index f627587..5cce385 100644
> --- a/drivers/media/platform/Kconfig
> +++ b/drivers/media/platform/Kconfig
> @@ -32,6 +32,14 @@ source "drivers/media/platform/davinci/Kconfig"
>  
>  source "drivers/media/platform/omap/Kconfig"
>  
> +config VIDEO_ASPEED
> +	tristate "Aspeed AST2400 and AST2500 Video Engine driver"
> +	depends on VIDEO_V4L2
> +	help
> +	  Support for the Aspeed Video Engine (VE) embedded in the Aspeed
> +	  AST2400 and AST2500 SOCs. The VE can capture and compress video data
> +	  from digital or analog sources.
> +
>  config VIDEO_SH_VOU
>  	tristate "SuperH VOU video output driver"
>  	depends on MEDIA_CAMERA_SUPPORT
> diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
> index 6ab6200..2973953 100644
> --- a/drivers/media/platform/Makefile
> +++ b/drivers/media/platform/Makefile
> @@ -3,6 +3,7 @@
>  # Makefile for the video capture/playback device drivers.
>  #
>  
> +obj-$(CONFIG_VIDEO_ASPEED)		+= aspeed-video.o
>  obj-$(CONFIG_VIDEO_CADENCE)		+= cadence/
>  obj-$(CONFIG_VIDEO_VIA_CAMERA) += via-camera.o
>  obj-$(CONFIG_VIDEO_CAFE_CCIC) += marvell-ccic/
> diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c
> new file mode 100644
> index 0000000..4f55c2e
> --- /dev/null
> +++ b/drivers/media/platform/aspeed-video.c
> @@ -0,0 +1,1469 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +
> +#include <linux/atomic.h>
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/interrupt.h>
> +#include <linux/jiffies.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_reserved_mem.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset.h>
> +#include <linux/sched.h>
> +#include <linux/spinlock.h>
> +#include <linux/string.h>
> +#include <linux/v4l2-controls.h>

No need for this,

> +#include <linux/videodev2.h>

it's already included by videodev2.h.

> +#include <linux/wait.h>
> +#include <linux/workqueue.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-dev.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-event.h>
> +#include <media/v4l2-ioctl.h>
> +
> +#define DEVICE_NAME			"aspeed-video"
> +
> +#define ASPEED_VIDEO_JPEG_NUM_QUALITIES	12
> +#define ASPEED_VIDEO_JPEG_HEADER_SIZE	10
> +#define ASPEED_VIDEO_JPEG_QUANT_SIZE	116
> +#define ASPEED_VIDEO_JPEG_DCT_SIZE	34
> +
> +#define MAX_FRAME_RATE			60
> +#define NUM_POLARITY_CHECKS		10
> +#define INVALID_RESOLUTION_RETRIES	1
> +#define INVALID_RESOLUTION_DELAY	msecs_to_jiffies(250)
> +#define RESOLUTION_CHANGE_DELAY		msecs_to_jiffies(500)
> +#define MODE_DETECT_TIMEOUT		msecs_to_jiffies(500)
> +#define DIRECT_FETCH_THRESHOLD		0x0c0000 /* 1024 * 768, 32bpp */
> +
> +#define VE_SRC_BUFFER_SIZE		0x900000 /* 1920 * 1200, 32bpp */
> +#define VE_COMP_BUFFER_SIZE		0x100000 /* 128K packet * 8 packets */
> +#define VE_JPEG_BUFFER_SIZE		0x006000 /* 512 * 12 * 4 */
> +
> +#define VE_PROTECTION_KEY		0x000
> +#define  VE_PROTECTION_KEY_UNLOCK	0x1A038AA8

The linux codingstyle is lower case hex (so A-F -> a-f).

> +
> +#define VE_SEQ_CTRL			0x004
> +#define  VE_SEQ_CTRL_TRIG_MODE_DET	BIT(0)
> +#define  VE_SEQ_CTRL_TRIG_CAPTURE	BIT(1)
> +#define  VE_SEQ_CTRL_FORCE_IDLE		BIT(2)
> +#define  VE_SEQ_CTRL_MULT_FRAME		BIT(3)
> +#define  VE_SEQ_CTRL_TRIG_COMP		BIT(4)
> +#define  VE_SEQ_CTRL_AUTO_COMP		BIT(5)
> +#define  VE_SEQ_CTRL_EN_WATCHDOG	BIT(7)
> +#define  VE_SEQ_CTRL_YUV420		BIT(10)
> +#define  VE_SEQ_CTRL_COMP_FMT		GENMASK(11, 10)
> +#define  VE_SEQ_CTRL_HALT		BIT(12)
> +#define  VE_SEQ_CTRL_EN_WATCHDOG_COMP	BIT(14)
> +#define  VE_SEQ_CTRL_TRIG_JPG		BIT(15)
> +#define  VE_SEQ_CTRL_CAP_BUSY		BIT(16)
> +#define  VE_SEQ_CTRL_COMP_BUSY		BIT(18)
> +
> +#ifdef CONFIG_MACH_ASPEED_G5
> +#define  VE_SEQ_CTRL_JPEG_MODE		BIT(13)	/* AST2500 */
> +#else
> +#define  VE_SEQ_CTRL_JPEG_MODE		BIT(8)	/* AST2400 */
> +#endif /* CONFIG_MACH_ASPEED_G5 */
> +
> +#define VE_CTRL				0x008
> +#define  VE_CTRL_HSYNC_POL		BIT(0)
> +#define  VE_CTRL_VSYNC_POL		BIT(1)
> +#define  VE_CTRL_SOURCE			BIT(2)
> +#define  VE_CTRL_INT_DE			BIT(4)
> +#define  VE_CTRL_DIRECT_FETCH		BIT(5)
> +#define  VE_CTRL_YUV			BIT(6)
> +#define  VE_CTRL_RGB			BIT(7)
> +#define  VE_CTRL_CAPTURE_FMT		GENMASK(7, 6)
> +#define  VE_CTRL_AUTO_OR_CURSOR		BIT(8)
> +#define  VE_CTRL_CLK_INVERSE		BIT(11)
> +#define  VE_CTRL_CLK_DELAY		GENMASK(11, 9)
> +#define  VE_CTRL_INTERLACE		BIT(14)
> +#define  VE_CTRL_HSYNC_POL_CTRL		BIT(15)
> +#define  VE_CTRL_FRC			GENMASK(23, 16)
> +
> +#define VE_TGS_0			0x00c
> +#define VE_TGS_1			0x010
> +#define  VE_TGS_FIRST			GENMASK(28, 16)
> +#define  VE_TGS_LAST			GENMASK(12, 0)
> +
> +#define VE_SCALING_FACTOR		0x014
> +#define VE_SCALING_FILTER0		0x018
> +#define VE_SCALING_FILTER1		0x01c
> +#define VE_SCALING_FILTER2		0x020
> +#define VE_SCALING_FILTER3		0x024
> +
> +#define VE_CAP_WINDOW			0x030
> +#define VE_COMP_WINDOW			0x034
> +#define VE_COMP_PROC_OFFSET		0x038
> +#define VE_COMP_OFFSET			0x03c
> +#define VE_JPEG_ADDR			0x040
> +#define VE_SRC0_ADDR			0x044
> +#define VE_SRC_SCANLINE_OFFSET		0x048
> +#define VE_SRC1_ADDR			0x04c
> +#define VE_COMP_ADDR			0x054
> +
> +#define VE_STREAM_BUF_SIZE		0x058
> +#define  VE_STREAM_BUF_SIZE_N_PACKETS	GENMASK(5, 3)
> +#define  VE_STREAM_BUF_SIZE_P_SIZE	GENMASK(2, 0)
> +
> +#define VE_COMP_CTRL			0x060
> +#define  VE_COMP_CTRL_VQ_DCT_ONLY	BIT(0)
> +#define  VE_COMP_CTRL_VQ_4COLOR		BIT(1)
> +#define  VE_COMP_CTRL_QUANTIZE		BIT(2)
> +#define  VE_COMP_CTRL_EN_BQ		BIT(4)
> +#define  VE_COMP_CTRL_EN_CRYPTO		BIT(5)
> +#define  VE_COMP_CTRL_DCT_CHR		GENMASK(10, 6)
> +#define  VE_COMP_CTRL_DCT_LUM		GENMASK(15, 11)
> +#define  VE_COMP_CTRL_EN_HQ		BIT(16)
> +#define  VE_COMP_CTRL_RSVD		BIT(19)
> +#define  VE_COMP_CTRL_ENCODE		GENMASK(21, 20)
> +#define  VE_COMP_CTRL_HQ_DCT_CHR	GENMASK(26, 22)
> +#define  VE_COMP_CTRL_HQ_DCT_LUM	GENMASK(31, 27)
> +
> +#define VE_OFFSET_COMP_STREAM		0x078
> +
> +#define VE_SRC_LR_EDGE_DET		0x090
> +#define  VE_SRC_LR_EDGE_DET_LEFT	GENMASK(11, 0)
> +#define  VE_SRC_LR_EDGE_DET_NO_V	BIT(12)
> +#define  VE_SRC_LR_EDGE_DET_NO_H	BIT(13)
> +#define  VE_SRC_LR_EDGE_DET_NO_DISP	BIT(14)
> +#define  VE_SRC_LR_EDGE_DET_NO_CLK	BIT(15)
> +#define  VE_SRC_LR_EDGE_DET_RT_SHF	16
> +#define  VE_SRC_LR_EDGE_DET_RT		GENMASK(27, VE_SRC_LR_EDGE_DET_RT_SHF)
> +#define  VE_SRC_LR_EDGE_DET_INTERLACE	BIT(31)
> +
> +#define VE_SRC_TB_EDGE_DET		0x094
> +#define  VE_SRC_TB_EDGE_DET_TOP		GENMASK(12, 0)
> +#define  VE_SRC_TB_EDGE_DET_BOT_SHF	16
> +#define  VE_SRC_TB_EDGE_DET_BOT		GENMASK(28, VE_SRC_TB_EDGE_DET_BOT_SHF)
> +
> +#define VE_MODE_DETECT_STATUS		0x098
> +#define  VE_MODE_DETECT_STATUS_VSYNC	BIT(28)
> +#define  VE_MODE_DETECT_STATUS_HSYNC	BIT(29)
> +
> +#define VE_INTERRUPT_CTRL		0x304
> +#define VE_INTERRUPT_STATUS		0x308
> +#define  VE_INTERRUPT_MODE_DETECT_WD	BIT(0)
> +#define  VE_INTERRUPT_CAPTURE_COMPLETE	BIT(1)
> +#define  VE_INTERRUPT_COMP_READY	BIT(2)
> +#define  VE_INTERRUPT_COMP_COMPLETE	BIT(3)
> +#define  VE_INTERRUPT_MODE_DETECT	BIT(4)
> +#define  VE_INTERRUPT_FRAME_COMPLETE	BIT(5)
> +#define  VE_INTERRUPT_DECODE_ERR	BIT(6)
> +#define  VE_INTERRUPT_HALT_READY	BIT(8)
> +#define  VE_INTERRUPT_HANG_WD		BIT(9)
> +#define  VE_INTERRUPT_STREAM_DESC	BIT(10)
> +#define  VE_INTERRUPT_VSYNC_DESC	BIT(11)
> +
> +#define VE_MODE_DETECT			0x30c
> +#define VE_MEM_RESTRICT_START		0x310
> +#define VE_MEM_RESTRICT_END		0x314
> +
> +enum {
> +	VIDEO_MODE_DETECT_DONE,
> +	VIDEO_RES_CHANGE,
> +	VIDEO_FRAME_AVAILABLE,
> +	VIDEO_FRAME_TRIGGERED,
> +};
> +
> +struct aspeed_video_addr {
> +	dma_addr_t dma;
> +	void *virt;
> +};
> +
> +struct aspeed_video {
> +	void __iomem *base;
> +	struct clk *eclk;
> +	struct clk *vclk;
> +	struct reset_control *rst;
> +
> +	struct device *dev;
> +	struct v4l2_ctrl_handler v4l2_ctrl;

Don't call this v4l2_ctrl. Most drivers just call this hdl or ctrl_handler.

> +	struct v4l2_device v4l2_dev;
> +	struct v4l2_format v4l2_fmt;

You probably want to use v4l2_pix_format here, using the full v4l2_format
struct is overkill.

> +	struct video_device vdev;
> +	struct mutex video_lock;
> +
> +	atomic_t clients;
> +	wait_queue_head_t wait;
> +	struct delayed_work res_work;
> +	unsigned long flags;
> +
> +	int frame_idx;
> +	u32 frame_size;
> +
> +	dma_addr_t max;
> +	dma_addr_t min;
> +	struct aspeed_video_addr srcs[2];
> +	struct aspeed_video_addr comp[2];
> +	struct aspeed_video_addr jpeg;
> +
> +	bool yuv420;
> +	int frame_rate;
> +	int jpeg_quality;
> +	unsigned int height;
> +	unsigned int width;
> +};
> +
> +#define to_aspeed_video(x) container_of((x), struct aspeed_video, v4l2_dev)
> +
> +static const u32 aspeed_video_jpeg_header[ASPEED_VIDEO_JPEG_HEADER_SIZE] = {
> +	0xE0FFD8FF, 0x464A1000, 0x01004649, 0x60000101, 0x00006000, 0x0F00FEFF,
> +	0x00002D05, 0x00000000, 0x00000000, 0x00DBFF00
> +};
> +
> +static const u32 aspeed_video_jpeg_quant[ASPEED_VIDEO_JPEG_QUANT_SIZE] = {
> +	0x081100C0, 0x00000000, 0x00110103, 0x03011102, 0xC4FF0111, 0x00001F00,
> +	0x01010501, 0x01010101, 0x00000000, 0x00000000, 0x04030201, 0x08070605,
> +	0xFF0B0A09, 0x10B500C4, 0x03010200, 0x03040203, 0x04040505, 0x7D010000,
> +	0x00030201, 0x12051104, 0x06413121, 0x07615113, 0x32147122, 0x08A19181,
> +	0xC1B14223, 0xF0D15215, 0x72623324, 0x160A0982, 0x1A191817, 0x28272625,
> +	0x35342A29, 0x39383736, 0x4544433A, 0x49484746, 0x5554534A, 0x59585756,
> +	0x6564635A, 0x69686766, 0x7574736A, 0x79787776, 0x8584837A, 0x89888786,
> +	0x9493928A, 0x98979695, 0xA3A29A99, 0xA7A6A5A4, 0xB2AAA9A8, 0xB6B5B4B3,
> +	0xBAB9B8B7, 0xC5C4C3C2, 0xC9C8C7C6, 0xD4D3D2CA, 0xD8D7D6D5, 0xE2E1DAD9,
> +	0xE6E5E4E3, 0xEAE9E8E7, 0xF4F3F2F1, 0xF8F7F6F5, 0xC4FFFAF9, 0x00011F00,
> +	0x01010103, 0x01010101, 0x00000101, 0x00000000, 0x04030201, 0x08070605,
> +	0xFF0B0A09, 0x11B500C4, 0x02010200, 0x04030404, 0x04040507, 0x77020100,
> +	0x03020100, 0x21050411, 0x41120631, 0x71610751, 0x81322213, 0x91421408,
> +	0x09C1B1A1, 0xF0523323, 0xD1726215, 0x3424160A, 0x17F125E1, 0x261A1918,
> +	0x2A292827, 0x38373635, 0x44433A39, 0x48474645, 0x54534A49, 0x58575655,
> +	0x64635A59, 0x68676665, 0x74736A69, 0x78777675, 0x83827A79, 0x87868584,
> +	0x928A8988, 0x96959493, 0x9A999897, 0xA5A4A3A2, 0xA9A8A7A6, 0xB4B3B2AA,
> +	0xB8B7B6B5, 0xC3C2BAB9, 0xC7C6C5C4, 0xD2CAC9C8, 0xD6D5D4D3, 0xDAD9D8D7,
> +	0xE5E4E3E2, 0xE9E8E7E6, 0xF4F3F2EA, 0xF8F7F6F5, 0xDAFFFAF9, 0x01030C00,
> +	0x03110200, 0x003F0011
> +};
> +
> +static const u32 aspeed_video_jpeg_dct[ASPEED_VIDEO_JPEG_NUM_QUALITIES]
> +				      [ASPEED_VIDEO_JPEG_DCT_SIZE] = {
> +	{ 0x0D140043, 0x0C0F110F, 0x11101114, 0x17141516, 0x1E20321E,
> +	  0x3D1E1B1B, 0x32242E2B, 0x4B4C3F48, 0x44463F47, 0x61735A50,
> +	  0x566C5550, 0x88644644, 0x7A766C65, 0x4D808280, 0x8C978D60,
> +	  0x7E73967D, 0xDBFF7B80, 0x1F014300, 0x272D2121, 0x3030582D,
> +	  0x697BB958, 0xB8B9B97B, 0xB9B8A6A6, 0xB9B9B9B9, 0xB9B9B9B9,
> +	  0xB9B9B9B9, 0xB9B9B9B9, 0xB9B9B9B9, 0xB9B9B9B9, 0xB9B9B9B9,
> +	  0xB9B9B9B9, 0xB9B9B9B9, 0xB9B9B9B9, 0xFFB9B9B9 },
> +	{ 0x0C110043, 0x0A0D0F0D, 0x0F0E0F11, 0x14111213, 0x1A1C2B1A,
> +	  0x351A1818, 0x2B1F2826, 0x4142373F, 0x3C3D373E, 0x55644E46,
> +	  0x4B5F4A46, 0x77573D3C, 0x6B675F58, 0x43707170, 0x7A847B54,
> +	  0x6E64836D, 0xDBFF6C70, 0x1B014300, 0x22271D1D, 0x2A2A4C27,
> +	  0x5B6BA04C, 0xA0A0A06B, 0xA0A0A0A0, 0xA0A0A0A0, 0xA0A0A0A0,
> +	  0xA0A0A0A0, 0xA0A0A0A0, 0xA0A0A0A0, 0xA0A0A0A0, 0xA0A0A0A0,
> +	  0xA0A0A0A0, 0xA0A0A0A0, 0xA0A0A0A0, 0xFFA0A0A0 },
> +	{ 0x090E0043, 0x090A0C0A, 0x0C0B0C0E, 0x110E0F10, 0x15172415,
> +	  0x2C151313, 0x241A211F, 0x36372E34, 0x31322E33, 0x4653413A,
> +	  0x3E4E3D3A, 0x62483231, 0x58564E49, 0x385D5E5D, 0x656D6645,
> +	  0x5B536C5A, 0xDBFF595D, 0x16014300, 0x1C201818, 0x22223F20,
> +	  0x4B58853F, 0x85858558, 0x85858585, 0x85858585, 0x85858585,
> +	  0x85858585, 0x85858585, 0x85858585, 0x85858585, 0x85858585,
> +	  0x85858585, 0x85858585, 0x85858585, 0xFF858585 },
> +	{ 0x070B0043, 0x07080A08, 0x0A090A0B, 0x0D0B0C0C, 0x11121C11,
> +	  0x23110F0F, 0x1C141A19, 0x2B2B2429, 0x27282428, 0x3842332E,
> +	  0x313E302E, 0x4E392827, 0x46443E3A, 0x2C4A4A4A, 0x50565137,
> +	  0x48425647, 0xDBFF474A, 0x12014300, 0x161A1313, 0x1C1C331A,
> +	  0x3D486C33, 0x6C6C6C48, 0x6C6C6C6C, 0x6C6C6C6C, 0x6C6C6C6C,
> +	  0x6C6C6C6C, 0x6C6C6C6C, 0x6C6C6C6C, 0x6C6C6C6C, 0x6C6C6C6C,
> +	  0x6C6C6C6C, 0x6C6C6C6C, 0x6C6C6C6C, 0xFF6C6C6C },
> +	{ 0x06090043, 0x05060706, 0x07070709, 0x0A09090A, 0x0D0E160D,
> +	  0x1B0D0C0C, 0x16101413, 0x21221C20, 0x1E1F1C20, 0x2B332824,
> +	  0x26302624, 0x3D2D1F1E, 0x3735302D, 0x22393A39, 0x3F443F2B,
> +	  0x38334338, 0xDBFF3739, 0x0D014300, 0x11130E0E, 0x15152613,
> +	  0x2D355026, 0x50505035, 0x50505050, 0x50505050, 0x50505050,
> +	  0x50505050, 0x50505050, 0x50505050, 0x50505050, 0x50505050,
> +	  0x50505050, 0x50505050, 0x50505050, 0xFF505050 },
> +	{ 0x04060043, 0x03040504, 0x05040506, 0x07060606, 0x09090F09,
> +	  0x12090808, 0x0F0A0D0D, 0x16161315, 0x14151315, 0x1D221B18,
> +	  0x19201918, 0x281E1514, 0x2423201E, 0x17262726, 0x2A2D2A1C,
> +	  0x25222D25, 0xDBFF2526, 0x09014300, 0x0B0D0A0A, 0x0E0E1A0D,
> +	  0x1F25371A, 0x37373725, 0x37373737, 0x37373737, 0x37373737,
> +	  0x37373737, 0x37373737, 0x37373737, 0x37373737, 0x37373737,
> +	  0x37373737, 0x37373737, 0x37373737, 0xFF373737 },
> +	{ 0x02030043, 0x01020202, 0x02020203, 0x03030303, 0x04040704,
> +	  0x09040404, 0x07050606, 0x0B0B090A, 0x0A0A090A, 0x0E110D0C,
> +	  0x0C100C0C, 0x140F0A0A, 0x1211100F, 0x0B131313, 0x1516150E,
> +	  0x12111612, 0xDBFF1213, 0x04014300, 0x05060505, 0x07070D06,
> +	  0x0F121B0D, 0x1B1B1B12, 0x1B1B1B1B, 0x1B1B1B1B, 0x1B1B1B1B,
> +	  0x1B1B1B1B, 0x1B1B1B1B, 0x1B1B1B1B, 0x1B1B1B1B, 0x1B1B1B1B,
> +	  0x1B1B1B1B, 0x1B1B1B1B, 0x1B1B1B1B, 0xFF1B1B1B },
> +	{ 0x01020043, 0x01010101, 0x01010102, 0x02020202, 0x03030503,
> +	  0x06030202, 0x05030404, 0x07070607, 0x06070607, 0x090B0908,
> +	  0x080A0808, 0x0D0A0706, 0x0C0B0A0A, 0x070C0D0C, 0x0E0F0E09,
> +	  0x0C0B0F0C, 0xDBFF0C0C, 0x03014300, 0x03040303, 0x04040804,
> +	  0x0A0C1208, 0x1212120C, 0x12121212, 0x12121212, 0x12121212,
> +	  0x12121212, 0x12121212, 0x12121212, 0x12121212, 0x12121212,
> +	  0x12121212, 0x12121212, 0x12121212, 0xFF121212 },
> +	{ 0x01020043, 0x01010101, 0x01010102, 0x02020202, 0x03030503,
> +	  0x06030202, 0x05030404, 0x07070607, 0x06070607, 0x090B0908,
> +	  0x080A0808, 0x0D0A0706, 0x0C0B0A0A, 0x070C0D0C, 0x0E0F0E09,
> +	  0x0C0B0F0C, 0xDBFF0C0C, 0x02014300, 0x03030202, 0x04040703,
> +	  0x080A0F07, 0x0F0F0F0A, 0x0F0F0F0F, 0x0F0F0F0F, 0x0F0F0F0F,
> +	  0x0F0F0F0F, 0x0F0F0F0F, 0x0F0F0F0F, 0x0F0F0F0F, 0x0F0F0F0F,
> +	  0x0F0F0F0F, 0x0F0F0F0F, 0x0F0F0F0F, 0xFF0F0F0F },
> +	{ 0x01010043, 0x01010101, 0x01010101, 0x01010101, 0x02020302,
> +	  0x04020202, 0x03020303, 0x05050405, 0x05050405, 0x07080606,
> +	  0x06080606, 0x0A070505, 0x09080807, 0x05090909, 0x0A0B0A07,
> +	  0x09080B09, 0xDBFF0909, 0x02014300, 0x02030202, 0x03030503,
> +	  0x07080C05, 0x0C0C0C08, 0x0C0C0C0C, 0x0C0C0C0C, 0x0C0C0C0C,
> +	  0x0C0C0C0C, 0x0C0C0C0C, 0x0C0C0C0C, 0x0C0C0C0C, 0x0C0C0C0C,
> +	  0x0C0C0C0C, 0x0C0C0C0C, 0x0C0C0C0C, 0xFF0C0C0C },
> +	{ 0x01010043, 0x01010101, 0x01010101, 0x01010101, 0x01010201,
> +	  0x03010101, 0x02010202, 0x03030303, 0x03030303, 0x04050404,
> +	  0x04050404, 0x06050303, 0x06050505, 0x03060606, 0x07070704,
> +	  0x06050706, 0xDBFF0606, 0x01014300, 0x01020101, 0x02020402,
> +	  0x05060904, 0x09090906, 0x09090909, 0x09090909, 0x09090909,
> +	  0x09090909, 0x09090909, 0x09090909, 0x09090909, 0x09090909,
> +	  0x09090909, 0x09090909, 0x09090909, 0xFF090909 },
> +	{ 0x01010043, 0x01010101, 0x01010101, 0x01010101, 0x01010101,
> +	  0x01010101, 0x01010101, 0x01010101, 0x01010101, 0x02020202,
> +	  0x02020202, 0x03020101, 0x03020202, 0x01030303, 0x03030302,
> +	  0x03020303, 0xDBFF0403, 0x01014300, 0x01010101, 0x01010201,
> +	  0x03040602, 0x06060604, 0x06060606, 0x06060606, 0x06060606,
> +	  0x06060606, 0x06060606, 0x06060606, 0x06060606, 0x06060606,
> +	  0x06060606, 0x06060606, 0x06060606, 0xFF060606 }
> +};
> +
> +static void aspeed_video_init_jpeg_table(u32 *table, bool yuv420)
> +{
> +	int i;
> +	unsigned int base;
> +
> +	for (i = 0; i < ASPEED_VIDEO_JPEG_NUM_QUALITIES; i++) {
> +		base = 256 * i;	/* AST HW requires this header spacing */
> +		memcpy(&table[base], aspeed_video_jpeg_header,
> +		       sizeof(aspeed_video_jpeg_header));
> +
> +		base += ASPEED_VIDEO_JPEG_HEADER_SIZE;
> +		memcpy(&table[base], aspeed_video_jpeg_dct[i],
> +		       sizeof(aspeed_video_jpeg_dct[i]));
> +
> +		base += ASPEED_VIDEO_JPEG_DCT_SIZE;
> +		memcpy(&table[base], aspeed_video_jpeg_quant,
> +		       sizeof(aspeed_video_jpeg_quant));
> +
> +		if (yuv420)
> +			table[base + 2] = 0x00220103;
> +	}
> +}
> +
> +static void aspeed_video_update(struct aspeed_video *video, u32 reg,
> +				unsigned long mask, u32 bits)
> +{
> +	u32 t = readl(video->base + reg);
> +	u32 before = t;
> +
> +	t &= mask;
> +	t |= bits;
> +	writel(t, video->base + reg);
> +	dev_dbg(video->dev, "update %03x[%08x -> %08x]\n", reg, before,
> +		readl(video->base + reg));
> +}
> +
> +static u32 aspeed_video_read(struct aspeed_video *video, u32 reg)
> +{
> +	u32 t = readl(video->base + reg);
> +
> +	dev_dbg(video->dev, "read %03x[%08x]\n", reg, t);
> +	return t;
> +}
> +
> +static void aspeed_video_write(struct aspeed_video *video, u32 reg, u32 val)
> +{
> +	writel(val, video->base + reg);
> +	dev_dbg(video->dev, "write %03x[%08x]\n", reg,
> +		readl(video->base + reg));
> +}
> +
> +static bool aspeed_video_engine_busy(struct aspeed_video *video)
> +{
> +	u32 seq_ctrl = aspeed_video_read(video, VE_SEQ_CTRL);
> +
> +	if (!(seq_ctrl & VE_SEQ_CTRL_COMP_BUSY) ||
> +	    !(seq_ctrl & VE_SEQ_CTRL_CAP_BUSY)) {
> +		dev_info(video->dev, "video engine busy\n");
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +static int aspeed_video_start_frame(struct aspeed_video *video)
> +{
> +	if (aspeed_video_engine_busy(video))
> +		return -EBUSY;
> +
> +	video->frame_idx = (video->frame_idx + 1) % 2;
> +
> +	aspeed_video_write(video, VE_COMP_PROC_OFFSET, 0);
> +	aspeed_video_write(video, VE_COMP_OFFSET, 0);
> +	aspeed_video_write(video, VE_COMP_ADDR,
> +			   video->comp[video->frame_idx].dma);
> +
> +	set_bit(VIDEO_FRAME_TRIGGERED, &video->flags);
> +
> +	aspeed_video_update(video, VE_INTERRUPT_CTRL, 0xFFFFFFFF,
> +			    VE_INTERRUPT_COMP_COMPLETE |
> +			    VE_INTERRUPT_CAPTURE_COMPLETE);
> +
> +	aspeed_video_update(video, VE_SEQ_CTRL, 0xFFFFFFFF,
> +			    VE_SEQ_CTRL_TRIG_CAPTURE | VE_SEQ_CTRL_TRIG_COMP);
> +
> +	return 0;
> +}
> +
> +static void aspeed_video_start_mode_detect(struct aspeed_video *video)
> +{
> +	/* Enable mode detect interrupts */
> +	aspeed_video_update(video, VE_INTERRUPT_CTRL, 0xFFFFFFFF,
> +			    VE_INTERRUPT_MODE_DETECT);
> +
> +	/* Trigger mode detect */
> +	aspeed_video_update(video, VE_SEQ_CTRL, 0xFFFFFFFF,
> +			    VE_SEQ_CTRL_TRIG_MODE_DET);
> +}
> +
> +static void aspeed_video_disable_mode_detect(struct aspeed_video *video)
> +{
> +	/* Disable mode detect interrupts */
> +	aspeed_video_update(video, VE_INTERRUPT_CTRL,
> +			    ~VE_INTERRUPT_MODE_DETECT, 0);
> +
> +	/* Disable mode detect */
> +	aspeed_video_update(video, VE_SEQ_CTRL, ~VE_SEQ_CTRL_TRIG_MODE_DET, 0);
> +}
> +
> +static void aspeed_video_off(struct aspeed_video *video)
> +{
> +	/* Reset the engine */
> +	reset_control_assert(video->rst);
> +	udelay(100);
> +	reset_control_deassert(video->rst);
> +
> +	/* Turn off the relevant clocks */
> +	clk_disable_unprepare(video->vclk);
> +	clk_disable_unprepare(video->eclk);
> +}
> +
> +static void aspeed_video_on(struct aspeed_video *video)
> +{
> +	/* Turn on the relevant clocks */
> +	clk_prepare_enable(video->eclk);
> +	clk_prepare_enable(video->vclk);
> +
> +	/* Reset the engine */
> +	reset_control_assert(video->rst);
> +	udelay(100);
> +	reset_control_deassert(video->rst);
> +}
> +
> +static irqreturn_t aspeed_video_irq(int irq, void *arg)
> +{
> +	struct aspeed_video *video = arg;
> +	u32 sts = aspeed_video_read(video, VE_INTERRUPT_STATUS);
> +
> +	if (atomic_read(&video->clients) == 0) {
> +		dev_info(video->dev, "irq with no client; disabling irqs\n");
> +
> +		aspeed_video_write(video, VE_INTERRUPT_CTRL, 0);
> +		aspeed_video_write(video, VE_INTERRUPT_STATUS, 0xFFFFFFFF);
> +		return IRQ_HANDLED;
> +	}
> +
> +	/* Resolution changed; reset entire engine and reinitialize */
> +	if (sts & VE_INTERRUPT_MODE_DETECT_WD) {
> +		dev_info(video->dev, "resolution changed; resetting\n");
> +		set_bit(VIDEO_RES_CHANGE, &video->flags);
> +
> +		aspeed_video_off(video);
> +
> +		schedule_delayed_work(&video->res_work,
> +				      RESOLUTION_CHANGE_DELAY);
> +		return IRQ_HANDLED;
> +	}
> +
> +	if (sts & VE_INTERRUPT_MODE_DETECT) {
> +		aspeed_video_update(video, VE_INTERRUPT_CTRL,
> +				    ~VE_INTERRUPT_MODE_DETECT, 0);
> +		aspeed_video_write(video, VE_INTERRUPT_STATUS,
> +				   VE_INTERRUPT_MODE_DETECT);
> +
> +		set_bit(VIDEO_MODE_DETECT_DONE, &video->flags);
> +		wake_up_interruptible_all(&video->wait);
> +	}
> +
> +	if ((sts & VE_INTERRUPT_COMP_COMPLETE) &&
> +	    (sts & VE_INTERRUPT_CAPTURE_COMPLETE)) {
> +		video->frame_size = aspeed_video_read(video,
> +						      VE_OFFSET_COMP_STREAM);
> +
> +		aspeed_video_update(video, VE_INTERRUPT_CTRL,
> +				    ~(VE_INTERRUPT_COMP_COMPLETE |
> +				      VE_INTERRUPT_CAPTURE_COMPLETE), 0);
> +		aspeed_video_write(video, VE_INTERRUPT_STATUS,
> +				   VE_INTERRUPT_COMP_COMPLETE |
> +				   VE_INTERRUPT_CAPTURE_COMPLETE);
> +		aspeed_video_update(video, VE_SEQ_CTRL,
> +				    ~(VE_SEQ_CTRL_TRIG_CAPTURE |
> +				      VE_SEQ_CTRL_FORCE_IDLE |
> +				      VE_SEQ_CTRL_TRIG_COMP), 0);
> +
> +		set_bit(VIDEO_FRAME_AVAILABLE, &video->flags);
> +		clear_bit(VIDEO_FRAME_TRIGGERED, &video->flags);
> +		wake_up_interruptible_all(&video->wait);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void aspeed_video_check_polarity(struct aspeed_video *video)
> +{
> +	int i;
> +	int hsync_counter = 0;
> +	int vsync_counter = 0;
> +	u32 sts;
> +
> +	for (i = 0; i < NUM_POLARITY_CHECKS; ++i) {
> +		sts = aspeed_video_read(video, VE_MODE_DETECT_STATUS);
> +		if (sts & VE_MODE_DETECT_STATUS_VSYNC)
> +			vsync_counter--;
> +		else
> +			vsync_counter++;
> +
> +		if (sts & VE_MODE_DETECT_STATUS_HSYNC)
> +			hsync_counter--;
> +		else
> +			hsync_counter++;
> +	}
> +
> +	if (hsync_counter < 0 || vsync_counter < 0) {
> +		u32 ctrl;
> +
> +		if (hsync_counter < 0)
> +			ctrl = VE_CTRL_HSYNC_POL;
> +
> +		if (vsync_counter < 0)
> +			ctrl = VE_CTRL_VSYNC_POL;
> +
> +		aspeed_video_update(video, VE_CTRL, 0xFFFFFFFF, ctrl);
> +	}
> +}
> +
> +#define res_check(v) test_and_clear_bit(VIDEO_MODE_DETECT_DONE, &(v)->flags)
> +
> +static int aspeed_video_get_resolution(struct aspeed_video *video)
> +{
> +	bool invalid_resolution = true;
> +	int rc;
> +	int tries = 0;
> +	unsigned int bottom;
> +	unsigned int left;
> +	unsigned int right;
> +	unsigned int top;
> +	u32 src_lr_edge;
> +	u32 src_tb_edge;
> +
> +	video->width = 0;
> +	video->height = 0;
> +
> +	do {
> +		if (tries) {
> +			set_current_state(TASK_INTERRUPTIBLE);
> +			if (schedule_timeout(INVALID_RESOLUTION_DELAY))
> +				return -EINTR;
> +		}
> +
> +		aspeed_video_start_mode_detect(video);
> +
> +		rc = wait_event_interruptible_timeout(video->wait,
> +						      res_check(video),
> +						      MODE_DETECT_TIMEOUT);
> +		if (!rc) {
> +			dev_err(video->dev, "timed out on 1st mode detect\n");
> +			aspeed_video_disable_mode_detect(video);
> +			return -ETIME;
> +		}
> +
> +		/* Disable mode detect in order to re-trigger */
> +		aspeed_video_update(video, VE_SEQ_CTRL,
> +				    ~VE_SEQ_CTRL_TRIG_MODE_DET, 0);
> +
> +		aspeed_video_check_polarity(video);
> +
> +		aspeed_video_start_mode_detect(video);
> +
> +		rc = wait_event_interruptible_timeout(video->wait,
> +						      res_check(video),
> +						      MODE_DETECT_TIMEOUT);
> +		if (!rc) {
> +			dev_err(video->dev, "timed out on 2nd mode detect\n");
> +			aspeed_video_disable_mode_detect(video);
> +			return -ETIME;
> +		}
> +
> +		src_lr_edge = aspeed_video_read(video, VE_SRC_LR_EDGE_DET);
> +		src_tb_edge = aspeed_video_read(video, VE_SRC_TB_EDGE_DET);
> +
> +		bottom = (src_tb_edge & VE_SRC_TB_EDGE_DET_BOT) >>
> +			VE_SRC_TB_EDGE_DET_BOT_SHF;
> +		top = src_tb_edge & VE_SRC_TB_EDGE_DET_TOP;
> +		if (top > bottom)
> +			continue;
> +
> +		right = (src_lr_edge & VE_SRC_LR_EDGE_DET_RT) >>
> +			VE_SRC_LR_EDGE_DET_RT_SHF;
> +		left = src_lr_edge & VE_SRC_LR_EDGE_DET_LEFT;
> +		if (left > right)
> +			continue;
> +
> +		invalid_resolution = false;
> +	} while (invalid_resolution && (tries++ < INVALID_RESOLUTION_RETRIES));
> +
> +	if (invalid_resolution) {
> +		dev_err(video->dev, "invalid resolution detected\n");
> +		return -EMSGSIZE;
> +	}
> +
> +	video->height = (bottom - top) + 1;
> +	video->width = (right - left) + 1;
> +
> +	/* Don't use direct mode below 1024 x 768 (irqs don't fire) */
> +	if (video->height * video->width < DIRECT_FETCH_THRESHOLD) {
> +		aspeed_video_write(video, VE_TGS_0,
> +				   FIELD_PREP(VE_TGS_FIRST, left - 1) |
> +				   FIELD_PREP(VE_TGS_LAST, right));
> +		aspeed_video_write(video, VE_TGS_1,
> +				   FIELD_PREP(VE_TGS_FIRST, top) |
> +				   FIELD_PREP(VE_TGS_LAST, bottom + 1));
> +		aspeed_video_update(video, VE_CTRL,
> +				    ~VE_CTRL_DIRECT_FETCH, VE_CTRL_INT_DE);
> +	}
> +
> +	aspeed_video_write(video, VE_CAP_WINDOW,
> +			   video->width << 16 | video->height);
> +	aspeed_video_write(video, VE_COMP_WINDOW,
> +			   video->width << 16 | video->height);
> +	aspeed_video_write(video, VE_SRC_SCANLINE_OFFSET, video->width * 4);
> +
> +	aspeed_video_update(video, VE_INTERRUPT_CTRL, 0xFFFFFFFF,
> +			    VE_INTERRUPT_MODE_DETECT_WD);
> +	aspeed_video_update(video, VE_SEQ_CTRL, 0xFFFFFFFF,
> +			    VE_SEQ_CTRL_EN_WATCHDOG);
> +
> +	dev_dbg(video->dev, "got resolution[%dx%d]\n", video->width,
> +		video->height);

This is where the DV_TIMINGS ioctls come in and the V4L2_EVENT_SOURCE_CHANGE
event.

> +
> +	return 0;
> +}
> +
> +static void aspeed_video_init_regs(struct aspeed_video *video)
> +{
> +	u32 comp_ctrl = VE_COMP_CTRL_RSVD |
> +		FIELD_PREP(VE_COMP_CTRL_DCT_LUM, video->jpeg_quality) |
> +		FIELD_PREP(VE_COMP_CTRL_DCT_CHR, video->jpeg_quality | 0x10);
> +	u32 ctrl = VE_CTRL_DIRECT_FETCH | VE_CTRL_AUTO_OR_CURSOR;
> +	u32 seq_ctrl = VE_SEQ_CTRL_AUTO_COMP | VE_SEQ_CTRL_JPEG_MODE;
> +
> +	if (video->frame_rate)
> +		ctrl |= FIELD_PREP(VE_CTRL_FRC, video->frame_rate);
> +
> +	if (video->yuv420)
> +		seq_ctrl |= VE_SEQ_CTRL_YUV420;
> +
> +	/* Unlock VE registers */
> +	aspeed_video_write(video, VE_PROTECTION_KEY, VE_PROTECTION_KEY_UNLOCK);
> +
> +	/* Disable interrupts */
> +	aspeed_video_write(video, VE_INTERRUPT_CTRL, 0);
> +	aspeed_video_write(video, VE_INTERRUPT_STATUS, 0xFFFFFFFF);
> +
> +	/* Clear the offset */
> +	aspeed_video_write(video, VE_COMP_PROC_OFFSET, 0);
> +	aspeed_video_write(video, VE_COMP_OFFSET, 0);
> +
> +	/* Set memory restrictions */
> +	aspeed_video_write(video, VE_MEM_RESTRICT_START, video->min);
> +	aspeed_video_write(video, VE_MEM_RESTRICT_END, video->max);
> +
> +	/* Set buffer addresses */
> +	aspeed_video_write(video, VE_SRC0_ADDR, video->srcs[0].dma);
> +	aspeed_video_write(video, VE_SRC1_ADDR, video->srcs[1].dma);
> +	aspeed_video_write(video, VE_COMP_ADDR, video->comp[0].dma);
> +	aspeed_video_write(video, VE_JPEG_ADDR, video->jpeg.dma);
> +
> +	/* Set control registers */
> +	aspeed_video_write(video, VE_SEQ_CTRL, seq_ctrl);
> +	aspeed_video_write(video, VE_CTRL, ctrl);
> +	aspeed_video_write(video, VE_COMP_CTRL, comp_ctrl);
> +
> +	/* Compression buffer size; 128K packet * 8 packets */
> +	aspeed_video_write(video, VE_STREAM_BUF_SIZE, 0xf);
> +
> +	/* Don't downscale */
> +	aspeed_video_write(video, VE_SCALING_FACTOR, 0x10001000);
> +	aspeed_video_write(video, VE_SCALING_FILTER0, 0x00200000);
> +	aspeed_video_write(video, VE_SCALING_FILTER1, 0x00200000);
> +	aspeed_video_write(video, VE_SCALING_FILTER2, 0x00200000);
> +	aspeed_video_write(video, VE_SCALING_FILTER3, 0x00200000);
> +
> +	/* Set mode detection defaults */
> +	aspeed_video_write(video, VE_MODE_DETECT, 0x22666500);
> +}
> +
> +static int aspeed_video_allocate_cma(struct aspeed_video *video)
> +{
> +	video->srcs[0].virt = dma_alloc_coherent(video->dev,
> +						 VE_SRC_BUFFER_SIZE,
> +						 &video->srcs[0].dma,
> +						 GFP_KERNEL);
> +	if (!video->srcs[0].virt) {
> +		dev_err(video->dev,
> +			"Failed to allocate source buffer 0, size[%x]\n",
> +			VE_SRC_BUFFER_SIZE);
> +		goto err;
> +	}
> +
> +	video->srcs[1].virt = dma_alloc_coherent(video->dev,
> +						 VE_SRC_BUFFER_SIZE,
> +						 &video->srcs[1].dma,
> +						 GFP_KERNEL);
> +	if (!video->srcs[1].virt) {
> +		dev_err(video->dev,
> +			"Failed to allocate source buffer 1, size[%x]\n",
> +			VE_SRC_BUFFER_SIZE);
> +		goto free_src0;
> +	}
> +
> +	video->comp[0].virt = dma_alloc_coherent(video->dev,
> +						 VE_COMP_BUFFER_SIZE,
> +						 &video->comp[0].dma,
> +						 GFP_KERNEL);
> +	if (!video->comp[0].virt) {
> +		dev_err(video->dev,
> +			"Failed to allocate compression buffer 0, size[%x]\n",
> +			VE_COMP_BUFFER_SIZE);
> +		goto free_src1;
> +	}
> +
> +	video->comp[1].virt = dma_alloc_coherent(video->dev,
> +						 VE_COMP_BUFFER_SIZE,
> +						 &video->comp[1].dma,
> +						 GFP_KERNEL);
> +	if (!video->comp[0].virt) {
> +		dev_err(video->dev,
> +			"Failed to allocate compression buffer 1, size[%x]\n",
> +			VE_COMP_BUFFER_SIZE);
> +		goto free_comp0;
> +	}
> +
> +	video->jpeg.virt = dma_alloc_coherent(video->dev, VE_JPEG_BUFFER_SIZE,
> +					      &video->jpeg.dma, GFP_KERNEL);
> +	if (!video->jpeg.virt) {
> +		dev_err(video->dev,
> +			"Failed to allocate JPEG buffer, size[%x]\n",
> +			VE_JPEG_BUFFER_SIZE);
> +		goto free_comp1;
> +	}

It looks like the buffers are allocated for a worst-case scenario (1080p I think).
So for smaller resolutions this wastes memory, but on the other hand you don't
need to reallocate buffers when the resolution changes.

Am I right?

> +
> +	aspeed_video_init_jpeg_table(video->jpeg.virt, video->yuv420);
> +
> +	/*
> +	 * Calculate the memory restrictions. Don't consider the JPEG header
> +	 * buffer since HW doesn't need to write to it.
> +	 */
> +	video->max = max(video->srcs[0].dma + VE_SRC_BUFFER_SIZE,
> +			 video->srcs[1].dma + VE_SRC_BUFFER_SIZE);
> +	video->max = max(video->max, video->comp[0].dma + VE_COMP_BUFFER_SIZE);
> +	video->max = max(video->max, video->comp[1].dma + VE_COMP_BUFFER_SIZE);
> +
> +	video->min = min(video->srcs[0].dma, video->srcs[1].dma);
> +	video->min = min(video->min, video->comp[0].dma);
> +	video->min = min(video->min, video->comp[1].dma);
> +
> +	return 0;
> +
> +free_comp1:
> +	dma_free_coherent(video->dev, VE_COMP_BUFFER_SIZE, video->comp[1].virt,
> +			  video->comp[1].dma);
> +	video->comp[1].dma = 0ULL;
> +	video->comp[1].virt = NULL;
> +
> +free_comp0:
> +	dma_free_coherent(video->dev, VE_COMP_BUFFER_SIZE, video->comp[0].virt,
> +			  video->comp[0].dma);
> +	video->comp[0].dma = 0ULL;
> +	video->comp[0].virt = NULL;
> +
> +free_src1:
> +	dma_free_coherent(video->dev, VE_SRC_BUFFER_SIZE, video->srcs[1].virt,
> +			  video->srcs[1].dma);
> +	video->srcs[1].dma = 0ULL;
> +	video->srcs[1].virt = NULL;
> +
> +free_src0:
> +	dma_free_coherent(video->dev, VE_SRC_BUFFER_SIZE, video->srcs[0].virt,
> +			  video->srcs[0].dma);
> +	video->srcs[0].dma = 0ULL;
> +	video->srcs[0].virt = NULL;
> +err:
> +	return -ENOMEM;
> +}
> +
> +static void aspeed_video_free_cma(struct aspeed_video *video)
> +{
> +	dma_free_coherent(video->dev, VE_JPEG_BUFFER_SIZE, video->jpeg.virt,
> +			  video->jpeg.dma);
> +	dma_free_coherent(video->dev, VE_COMP_BUFFER_SIZE, video->comp[1].virt,
> +			  video->comp[1].dma);
> +	dma_free_coherent(video->dev, VE_COMP_BUFFER_SIZE, video->comp[0].virt,
> +			  video->comp[0].dma);
> +	dma_free_coherent(video->dev, VE_SRC_BUFFER_SIZE, video->srcs[1].virt,
> +			  video->srcs[1].dma);
> +	dma_free_coherent(video->dev, VE_SRC_BUFFER_SIZE, video->srcs[0].virt,
> +			  video->srcs[0].dma);
> +
> +	video->srcs[0].dma = 0ULL;
> +	video->srcs[0].virt = NULL;
> +	video->srcs[1].dma = 0ULL;
> +	video->srcs[1].virt = NULL;
> +	video->comp[0].dma = 0ULL;
> +	video->comp[0].virt = NULL;
> +	video->comp[1].dma = 0ULL;
> +	video->comp[1].virt = NULL;
> +	video->jpeg.dma = 0ULL;
> +	video->jpeg.virt = NULL;
> +}
> +
> +static int aspeed_video_start(struct aspeed_video *video)
> +{
> +	int rc = aspeed_video_allocate_cma(video);
> +
> +	if (rc)
> +		return rc;
> +
> +	aspeed_video_on(video);
> +
> +	aspeed_video_init_regs(video);
> +
> +	rc = aspeed_video_get_resolution(video);
> +	if (rc)
> +		aspeed_video_free_cma(video);
> +
> +	video->v4l2_fmt.fmt.pix.width = video->width;
> +	video->v4l2_fmt.fmt.pix.height = video->height;
> +	video->v4l2_fmt.fmt.pix.sizeimage = video->width * video->height * 4;

If you use JPEG compression, why is sizeimage set to the raw image size?
That's for an extreme case where JPEG can't compress the image at all?
But would this be too small in that situation since it doesn't have room
for the JPEG header?

> +
> +	clear_bit(VIDEO_FRAME_TRIGGERED, &video->flags);
> +
> +	return rc;
> +}
> +
> +static void aspeed_video_stop(struct aspeed_video *video)
> +{
> +	cancel_delayed_work_sync(&video->res_work);
> +
> +	aspeed_video_off(video);
> +
> +	aspeed_video_free_cma(video);
> +
> +	clear_bit(VIDEO_FRAME_AVAILABLE, &video->flags);
> +}
> +
> +static int aspeed_video_querycap(struct file *file, void *fh,
> +				 struct v4l2_capability *cap)
> +{
> +	strlcpy(cap->driver, DEVICE_NAME, sizeof(cap->driver));
> +	strlcpy(cap->card, "Aspeed Video Engine", sizeof(cap->card));

Use strscpy instead of strlcpy (just rename).

The plan is that strscpy will replace all strcpy, strncpy and strlcpy usages
in the kernel.

> +	snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:%s",
> +		 DEVICE_NAME);
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_enum_format(struct file *file, void *fh,
> +				    struct v4l2_fmtdesc *f)
> +{
> +	if (f->index)
> +		return -EINVAL;
> +
> +	f->pixelformat = V4L2_PIX_FMT_JPEG;
> +	strlcpy(f->description, "JPEG", sizeof(f->description));

1) use strscpy instead of strlcpy (a recent change).
2) drop this line altogether since it will be filled in for you by the V4L2 core.

> +	f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	f->flags = V4L2_FMT_FLAG_COMPRESSED;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_get_format(struct file *file, void *fh,
> +				   struct v4l2_format *f)
> +{
> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	*f = video->v4l2_fmt;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_set_format(struct file *file, void *fh,
> +				   struct v4l2_format *f)
> +{
> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	if (f->fmt.pix.width == video->width)
> +		video->v4l2_fmt.fmt.pix.width = video->width;
> +
> +	if (f->fmt.pix.height == video->height)
> +		video->v4l2_fmt.fmt.pix.height = video->height;

What's the point of this? Just set aspeed_video_get_format as the
callback for the g/s/try callbacks.

The application cannot change the format at all, so doing that is
fine.

> +
> +	return aspeed_video_get_format(file, fh, f);
> +}
> +
> +static int aspeed_video_try_format(struct file *file, void *fh,
> +				   struct v4l2_format *f)
> +{
> +	int rc;
> +	struct aspeed_video *video = video_drvdata(file);
> +	struct v4l2_pix_format pix = f->fmt.pix;
> +
> +	rc = aspeed_video_get_format(file, fh, f);
> +	if (rc)
> +		return rc;
> +
> +	if (pix.width == video->width)
> +		f->fmt.pix.width = video->width;
> +
> +	if (pix.height == video->height)
> +		f->fmt.pix.height = video->height;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_enum_input(struct file *file, void *fh,
> +				   struct v4l2_input *inp)
> +{
> +	if (inp->index)
> +		return -EINVAL;
> +
> +	strlcpy(inp->name, "Host VGA capture", sizeof(inp->name));
> +	inp->type = V4L2_INPUT_TYPE_CAMERA;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_get_input(struct file *file, void *fh, unsigned int *i)
> +{
> +	*i = 0;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_set_input(struct file *file, void *fh, unsigned int i)
> +{
> +	if (i)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_get_parm(struct file *file, void *fh,
> +				 struct v4l2_streamparm *a)
> +{
> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	a->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

Just drop this line. It's checked by the v4l2 core for you.

> +	a->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
> +	a->parm.capture.timeperframe.numerator = 1;
> +	if (!video->frame_rate)
> +		a->parm.capture.timeperframe.denominator = MAX_FRAME_RATE + 1;
> +	else
> +		a->parm.capture.timeperframe.denominator = video->frame_rate;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_set_parm(struct file *file, void *fh,
> +				 struct v4l2_streamparm *a)
> +{
> +	int frame_rate;

unsigned int.

> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	if (a->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
> +		return -EINVAL;

Same here: just drop the check, it's not needed.

> +
> +	a->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
> +
> +	if (a->parm.capture.timeperframe.numerator) {
> +		frame_rate = a->parm.capture.timeperframe.denominator /
> +			a->parm.capture.timeperframe.numerator;

frame_rate can be 0 if denominator is 0,

> +	} else {
> +		frame_rate = 0;
> +		a->parm.capture.timeperframe.numerator = 1;

and then this isn't set to 1.

v4l2-compliance was missing a test for this. I've added one, so I think it
should now fail when run against this driver. Could you test that?

> +	}
> +
> +	if (frame_rate < 0 || frame_rate > MAX_FRAME_RATE)
> +		frame_rate = 0;
> +
> +	if (!frame_rate)
> +		a->parm.capture.timeperframe.denominator = MAX_FRAME_RATE + 1;

Why MAX_FRAME_RATE + 1 and not MAX_FRAME_RATE?

> +
> +	if (video->frame_rate != frame_rate) {
> +		video->frame_rate = frame_rate;
> +		aspeed_video_update(video, VE_CTRL, ~VE_CTRL_FRC,
> +				    FIELD_PREP(VE_CTRL_FRC, frame_rate));

So the frame rate is set by userspace and is not related to the actual
host graphics framerate?

> +	}
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_enum_framesizes(struct file *file, void *fh,
> +					struct v4l2_frmsizeenum *fsize)
> +{
> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	if (fsize->pixel_format != V4L2_PIX_FMT_JPEG)
> +		return -EINVAL;
> +
> +	switch (fsize->index) {
> +	case 0:
> +		fsize->discrete.width = video->v4l2_fmt.fmt.pix.width;
> +		fsize->discrete.height = video->v4l2_fmt.fmt.pix.height;
> +		break;
> +	case 1:
> +		if (video->width == video->v4l2_fmt.fmt.pix.width &&
> +		    video->height == video->v4l2_fmt.fmt.pix.height)
> +			return -EINVAL;
> +
> +		fsize->discrete.width = video->width;
> +		fsize->discrete.height = video->height;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	fsize->type = V4L2_FRMSIZE_TYPE_DISCRETE;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_enum_frameintervals(struct file *file, void *fh,
> +					    struct v4l2_frmivalenum *fival)
> +{
> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	if (fival->index)
> +		return -EINVAL;
> +
> +	if (fival->width != video->width || fival->height != video->height)
> +		return -EINVAL;
> +
> +	if (fival->pixel_format != V4L2_PIX_FMT_JPEG)
> +		return -EINVAL;
> +
> +	fival->type = V4L2_FRMIVAL_TYPE_CONTINUOUS;
> +
> +	fival->stepwise.min.denominator = MAX_FRAME_RATE;
> +	fival->stepwise.min.numerator = 1;
> +	fival->stepwise.max.denominator = 1;
> +	fival->stepwise.max.numerator = 1;
> +	fival->stepwise.step = fival->stepwise.max;
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_ioctl_ops aspeed_video_ioctl_ops = {
> +	.vidioc_querycap = aspeed_video_querycap,
> +	.vidioc_enum_fmt_vid_cap = aspeed_video_enum_format,
> +	.vidioc_g_fmt_vid_cap = aspeed_video_get_format,
> +	.vidioc_s_fmt_vid_cap = aspeed_video_set_format,
> +	.vidioc_try_fmt_vid_cap = aspeed_video_try_format,
> +	.vidioc_enum_input = aspeed_video_enum_input,
> +	.vidioc_g_input = aspeed_video_get_input,
> +	.vidioc_s_input = aspeed_video_set_input,
> +	.vidioc_g_parm = aspeed_video_get_parm,
> +	.vidioc_s_parm = aspeed_video_set_parm,
> +	.vidioc_enum_framesizes = aspeed_video_enum_framesizes,
> +	.vidioc_enum_frameintervals = aspeed_video_enum_frameintervals,
> +	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
> +	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
> +};
> +
> +static void aspeed_video_update_jpeg_quality(struct aspeed_video *video)
> +{
> +	u32 comp_ctrl = FIELD_PREP(VE_COMP_CTRL_DCT_LUM, video->jpeg_quality) |
> +		FIELD_PREP(VE_COMP_CTRL_DCT_CHR, video->jpeg_quality | 0x10);
> +
> +	aspeed_video_update(video, VE_COMP_CTRL,
> +			    ~(VE_COMP_CTRL_DCT_LUM | VE_COMP_CTRL_DCT_CHR),
> +			    comp_ctrl);
> +}
> +
> +static void aspeed_video_update_subsampling(struct aspeed_video *video)
> +{
> +	if (video->jpeg.virt)
> +		aspeed_video_init_jpeg_table(video->jpeg.virt, video->yuv420);
> +
> +	if (video->yuv420)
> +		aspeed_video_update(video, VE_SEQ_CTRL, 0xFFFFFFFF,
> +				    VE_SEQ_CTRL_YUV420);
> +	else
> +		aspeed_video_update(video, VE_SEQ_CTRL, ~VE_SEQ_CTRL_YUV420,
> +				    0);
> +}
> +
> +static int aspeed_video_set_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +	struct aspeed_video *video = container_of(ctrl->handler,
> +						  struct aspeed_video,
> +						  v4l2_ctrl);
> +
> +	switch (ctrl->id) {
> +	case V4L2_CID_JPEG_COMPRESSION_QUALITY:
> +		if (video->jpeg_quality != ctrl->val) {

No need to check if the value is different: this is only called if the value is
indeed different.

> +			video->jpeg_quality = ctrl->val;
> +			aspeed_video_update_jpeg_quality(video);
> +		}
> +		break;
> +	case V4L2_CID_JPEG_CHROMA_SUBSAMPLING:
> +		if (ctrl->val == V4L2_JPEG_CHROMA_SUBSAMPLING_420) {
> +			if (!video->yuv420) {

Ditto.

> +				video->yuv420 = true;
> +				aspeed_video_update_subsampling(video);
> +			}
> +		} else {
> +			if (video->yuv420) {
> +				video->yuv420 = false;
> +				aspeed_video_update_subsampling(video);
> +			}
> +		}
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_ctrl_ops aspeed_video_ctrl_ops = {
> +	.s_ctrl = aspeed_video_set_ctrl,
> +};
> +
> +static void aspeed_video_resolution_work(struct work_struct *work)
> +{
> +	int rc;
> +	struct delayed_work *dwork = to_delayed_work(work);
> +	struct aspeed_video *video = container_of(dwork, struct aspeed_video,
> +						  res_work);
> +
> +	/* No clients remaining after delay */
> +	if (atomic_read(&video->clients) == 0)
> +		goto done;
> +
> +	aspeed_video_on(video);
> +
> +	aspeed_video_init_regs(video);
> +
> +	rc = aspeed_video_get_resolution(video);
> +	if (rc) {
> +		dev_err(video->dev,
> +			"resolution changed; couldn't get new resolution\n");
> +	} else {
> +		video->frame_idx = 0;
> +		clear_bit(VIDEO_FRAME_TRIGGERED, &video->flags);
> +	}
> +
> +done:
> +	clear_bit(VIDEO_RES_CHANGE, &video->flags);
> +	wake_up_interruptible_all(&video->wait);
> +}
> +
> +static bool aspeed_video_frame_available(struct aspeed_video *video)
> +{
> +	if (!test_and_clear_bit(VIDEO_FRAME_AVAILABLE, &video->flags)) {
> +		if (!test_bit(VIDEO_FRAME_TRIGGERED, &video->flags))
> +			aspeed_video_start_frame(video);
> +
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static ssize_t aspeed_video_file_read(struct file *file, char __user *buf,
> +				      size_t count, loff_t *ppos)
> +{
> +	int rc;
> +	int fidx;
> +	size_t size;
> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	if (mutex_lock_interruptible(&video->video_lock))
> +		return -EINTR;
> +
> +	if (file->f_flags & O_NONBLOCK) {
> +		if (!aspeed_video_frame_available(video)) {
> +			rc = -EAGAIN;
> +			goto unlock;
> +		} else {
> +			goto ready;
> +		}
> +	}
> +
> +	rc = wait_event_interruptible(video->wait,
> +				      aspeed_video_frame_available(video));
> +	if (rc) {
> +		rc = -EINTR;
> +		goto unlock;
> +	}
> +
> +ready:
> +	fidx = video->frame_idx;
> +	size = min_t(size_t, video->frame_size, count);
> +	aspeed_video_start_frame(video);
> +
> +	if (copy_to_user(buf, video->comp[fidx].virt, size)) {
> +		rc = -EFAULT;
> +		goto unlock;
> +	}
> +
> +	rc = size;
> +
> +unlock:
> +	mutex_unlock(&video->video_lock);
> +	return rc;
> +}
> +
> +static int aspeed_video_open(struct file *file)
> +{
> +	int rc;
> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	if (atomic_inc_return(&video->clients) == 1) {
> +		rc = aspeed_video_start(video);
> +		if (rc) {
> +			dev_err(video->dev, "Failed to start video engine\n");
> +			atomic_dec(&video->clients);
> +			return rc;
> +		}
> +	}
> +
> +	return v4l2_fh_open(file);
> +}
> +
> +static int aspeed_video_release(struct file *file)
> +{
> +	int rc;
> +	struct aspeed_video *video = video_drvdata(file);
> +
> +	rc = v4l2_fh_release(file);
> +
> +	if (atomic_dec_return(&video->clients) == 0)
> +		aspeed_video_stop(video);
> +
> +	return rc;
> +}
> +
> +static const struct v4l2_file_operations aspeed_video_v4l2_fops = {
> +	.owner = THIS_MODULE,
> +	.read = aspeed_video_file_read,
> +	.poll = v4l2_ctrl_poll,
> +	.unlocked_ioctl = video_ioctl2,
> +	.open = aspeed_video_open,
> +	.release = aspeed_video_release,
> +};
> +
> +static void aspeed_video_device_release(struct video_device *vdev)
> +{
> +}
> +
> +static int aspeed_video_setup_video(struct aspeed_video *video)
> +{
> +	int rc;
> +	u64 mask = ~(BIT(V4L2_JPEG_CHROMA_SUBSAMPLING_444) |
> +		     BIT(V4L2_JPEG_CHROMA_SUBSAMPLING_420));
> +	struct v4l2_device *v4l2_dev = &video->v4l2_dev;
> +	struct video_device *vdev = &video->vdev;
> +
> +	rc = v4l2_device_register(video->dev, v4l2_dev);
> +	if (rc) {
> +		dev_err(video->dev, "Failed to register v4l2 device\n");
> +		return rc;
> +	}
> +
> +	vdev->fops = &aspeed_video_v4l2_fops;
> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_READWRITE;
> +	vdev->v4l2_dev = v4l2_dev;
> +	strncpy(vdev->name, DEVICE_NAME, sizeof(vdev->name));

strscpy

> +	vdev->vfl_type = VFL_TYPE_GRABBER;
> +	vdev->vfl_dir = VFL_DIR_RX;
> +	vdev->release = aspeed_video_device_release;

Use the video_device_release_empty helper instead. Now you can drop aspeed_video_device_release.

> +	vdev->ioctl_ops = &aspeed_video_ioctl_ops;
> +	vdev->lock = &video->video_lock;
> +
> +	video_set_drvdata(vdev, video);
> +	rc = video_register_device(vdev, VFL_TYPE_GRABBER, 0);

This should be done last in probe(). After this call the video node appears and
can be used by userspace, so everything must be fully initialized and that's
not the case.

> +	if (rc) {
> +		v4l2_device_unregister(v4l2_dev);
> +		dev_err(video->dev, "Failed to register video device\n");
> +		return rc;
> +	}
> +
> +	video->v4l2_fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	video->v4l2_fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_JPEG;
> +	video->v4l2_fmt.fmt.pix.field = V4L2_FIELD_NONE;
> +	video->v4l2_fmt.fmt.pix.colorspace = V4L2_COLORSPACE_JPEG;

COLORSPACE_JPEG is deprecated. Use V4L2_COLORSPACE_SRGB for pix.colorspace
and set pix.quantization to V4L2_QUANTIZATION_FULL_RANGE.

> +
> +	/* Don't fail the probe if controls init fails */
> +	v4l2_ctrl_handler_init(&video->v4l2_ctrl, 2);
> +
> +	v4l2_ctrl_new_std(&video->v4l2_ctrl, &aspeed_video_ctrl_ops,
> +			  V4L2_CID_JPEG_COMPRESSION_QUALITY, 0,
> +			  ASPEED_VIDEO_JPEG_NUM_QUALITIES - 1, 1, 0);
> +
> +	v4l2_ctrl_new_std_menu(&video->v4l2_ctrl, &aspeed_video_ctrl_ops,
> +			       V4L2_CID_JPEG_CHROMA_SUBSAMPLING,
> +			       V4L2_JPEG_CHROMA_SUBSAMPLING_420, mask,
> +			       V4L2_JPEG_CHROMA_SUBSAMPLING_444);
> +
> +	if (video->v4l2_ctrl.error) {
> +		dev_info(video->dev, "Failed to init controls: %d\n",
> +			 video->v4l2_ctrl.error);
> +		v4l2_ctrl_handler_free(&video->v4l2_ctrl);

You really need to return an error here, you shouldn't continue.

> +	} else {
> +		v4l2_dev->ctrl_handler = &video->v4l2_ctrl;
> +		vdev->ctrl_handler = &video->v4l2_ctrl;
> +	}
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_init(struct aspeed_video *video)
> +{
> +	int irq;
> +	int rc;
> +	struct device *dev = video->dev;
> +
> +	irq = irq_of_parse_and_map(dev->of_node, 0);
> +	if (!irq) {
> +		dev_err(dev, "Unable to find IRQ\n");
> +		return -ENODEV;
> +	}
> +
> +	rc = devm_request_irq(dev, irq, aspeed_video_irq, IRQF_SHARED,
> +			      DEVICE_NAME, video);
> +	if (rc < 0) {
> +		dev_err(dev, "Unable to request IRQ %d\n", irq);
> +		return rc;
> +	}
> +
> +	video->eclk = devm_clk_get(dev, "eclk");
> +	if (IS_ERR(video->eclk)) {
> +		dev_err(dev, "Unable to get ECLK\n");
> +		return PTR_ERR(video->eclk);
> +	}
> +
> +	video->vclk = devm_clk_get(dev, "vclk");
> +	if (IS_ERR(video->vclk)) {
> +		dev_err(dev, "Unable to get VCLK\n");
> +		return PTR_ERR(video->vclk);
> +	}
> +
> +	video->rst = devm_reset_control_get_exclusive(dev, NULL);
> +	if (IS_ERR(video->rst)) {
> +		dev_err(dev, "Unable to get VE reset\n");
> +		return PTR_ERR(video->rst);
> +	}
> +
> +	rc = of_reserved_mem_device_init(dev);
> +	if (rc) {
> +		dev_err(dev, "Unable to reserve memory\n");
> +		return rc;
> +	}
> +
> +	rc = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
> +	if (rc) {
> +		dev_err(dev, "Failed to set DMA mask\n");
> +		of_reserved_mem_device_release(dev);
> +		return rc;
> +	}
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_probe(struct platform_device *pdev)
> +{
> +	int rc;
> +	struct resource *res;
> +	struct aspeed_video *video = kzalloc(sizeof(*video), GFP_KERNEL);
> +
> +	if (!video)
> +		return -ENOMEM;
> +
> +	video->frame_rate = 30;
> +	video->dev = &pdev->dev;
> +	mutex_init(&video->video_lock);
> +	init_waitqueue_head(&video->wait);
> +	INIT_DELAYED_WORK(&video->res_work, aspeed_video_resolution_work);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> +	video->base = devm_ioremap_resource(video->dev, res);
> +
> +	if (IS_ERR(video->base))
> +		return PTR_ERR(video->base);
> +
> +	rc = aspeed_video_init(video);
> +	if (rc)
> +		return rc;
> +
> +	rc = aspeed_video_setup_video(video);
> +	if (rc)
> +		return rc;
> +
> +	return 0;
> +}
> +
> +static int aspeed_video_remove(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct v4l2_device *v4l2_dev = dev_get_drvdata(dev);
> +	struct aspeed_video *video = to_aspeed_video(v4l2_dev);
> +
> +	if (video->vdev.ctrl_handler)
> +		v4l2_ctrl_handler_free(&video->v4l2_ctrl);
> +
> +	video_unregister_device(&video->vdev);
> +
> +	v4l2_device_unregister(v4l2_dev);
> +
> +	of_reserved_mem_device_release(dev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id aspeed_video_of_match[] = {
> +	{ .compatible = "aspeed,ast2400-video-engine" },
> +	{ .compatible = "aspeed,ast2500-video-engine" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, aspeed_video_of_match);
> +
> +static struct platform_driver aspeed_video_driver = {
> +	.driver = {
> +		.name = DEVICE_NAME,
> +		.of_match_table = aspeed_video_of_match,
> +	},
> +	.probe = aspeed_video_probe,
> +	.remove = aspeed_video_remove,
> +};
> +
> +module_platform_driver(aspeed_video_driver);
> +
> +MODULE_DESCRIPTION("ASPEED Video Engine Driver");
> +MODULE_AUTHOR("Eddie James");
> +MODULE_LICENSE("GPL v2");
> 

I don't like the read() API here. It is not a real read() either since it assumes
userspace reads full frames at a time. But if you read e.g. one byte at a time,
then each byte is just the first byte of a different frame.

I think we need to figure out how to make the stream I/O version just as fast
if not faster as the read() API.

Regards,

	Hans