【全志平台】A64平台 TP9950 BT656输入驱动调试（1）环境搭建&驱动编写_专栏

1. 前言

由于需要在全志A64平台上接入模拟相机，这里选型的模拟转换芯片是TP9950;
（1）TP9950可以通过CSI接口输出，也可以通过并行的BT656接口输出；
（2）由于A64平台没有MIPI接口，只有并行接口【可支持BT656输入】，
所以TP9950只能通过并行接口连接。

2. A64平台环境搭建

由于A64平台是针对android系统的，但是由于驱动部分调试只与内核有关，
所以可以只搭建内核环境，可以不用搭建android环境【这个毕竟也要点时间】。

（1）配置lichee环境

配置完后运行 ./build.sh

(2) 打包

./build.sh pack

（3）编译完成

（4）烧写镜像

烧写时通过串口输入2，然后插上USB线即可
进入账号输入root即可，然后可以进入linux系统

3. BT656接口camera驱动编写

编写驱动和dts
参考a64/lichee/linux-3.10/drivers/media/platform/sunxi-vfe/device/tw2866.c

（1）移植驱动

a. 修改sensor name，配置TP9950 init reg
b. i2c addr 0x44 (1000100)

我这边调试的设备TP9950,查看datasheet 得出I2C地址是0x44

另外硬件上也是可以修改I2C地址的

(2)修改平台端接口参数

使用 BT656 接口的器件时，如 TV decoder，一般是输入 PAL/NTSC 两种格式的视频信号，
其信号一般是固定为 UYVY 的，只需要填写一组即可。
static struct sensor_format_struct {
__u8 *desc;
//__u32 pixelformat;
enum v4l2_mbus_pixelcode mbus_code;
struct regval_list *regs;
int regs_size;
int bpp; /* Bytes per pixel */
} sensor_formats[] = {
{
.desc = "UYVY 4:2:2",
.mbus_code = V4L2_MBUS_FMT_UYVY8_2X8,
.regs = sensor_fmt_yuv422_uyvy,
.regs_size = ARRAY_SIZE(sensor_fmt_yuv422_uyvy),
.bpp = 2,
}

主控端需要配置成的相应参数：
并口的 sensor 填写接口参数（YUV/RAW）

static int sensor_g_mbus_config(struct v4l2_subdev *sd,
struct v4l2_mbus_config *cfg)
{
cfg->type = V4L2_MBUS_PARALLEL;
cfg->flags = V4L2_MBUS_MASTER | VREF_POL | HREF_POL | CLK_POL ;
return 0;
}

BT656 信号输入时候填写接口参数（YUV）

static int sensor_g_mbus_config(struct v4l2_subdev *sd,
struct v4l2_mbus_config *cfg)
{
cfg->type = V4L2_MBUS_BT656;
cfg->flags = 0 ;//no use here
return 0;
}

BT656 的设备可以仅仅实现 PAL/NTSC 两种 size，其中 PAL 的是每秒 50 场/25fps，NTSC
是每秒 60 场/30fps，一般是将这种信号以 frame 的形式接受下来（与主控后面显示和编码有
关，一般是接收成 frame 的形式）。如果该器件有其他格式的话逐个实现即可。

static struct sensor_win_size sensor_win_sizes[] = {
/* PAL */
{
.width = 704,
.height = 480,
.hoffset = 0,
.voffset = 0,
.regs = sensor_pal_regs,
.regs_size = ARRAY_SIZE(sensor_pal_regs),
.set_size = NULL,
},
/* NTSC */
{
.width = 704
.height = 576,
.hoffset = 0,
.voffset = 0,
.regs = sensor_ntsc_regs,
.regs_size = ARRAY_SIZE(sensor_ntsc_regs),
.set_size = NULL,
},
};

(3)加载驱动

insmod videobuf2-core.ko
insmod videobuf2-memops.ko
insmod videobuf2-dma-contig.ko
insmod vfe_io.ko
insmod tp9950.ko
insmod vfe_v4l2.ko

# [  104.510035] [VFE]probe_work_handle start!
[  104.514633] [VFE]vfe_runtime_resume
[  104.530018] [VFE]..........................vfe clk open!.......................
[  104.538011] [VFE]v4l2 subdev register input_num = 0
[  104.543753] [VFE_ERR]get regulator csi_flvdd error!
[  104.549074] [VFE_ERR]vfe_device_regulator_get error at input_num = 0
[  104.556228] [VFE]v4l2 subdev register input_num = 1
[  104.561657] axp81x_aldo1: Failed to create debugfs directory
[  104.567839] axp81x_aldo2: Failed to create debugfs directory
[  104.574235] axp81x_eldo3: Failed to create debugfs directory
[  104.580526] [VFE_ERR]get regulator csi_flvdd error!
[  104.585846] [VFE_ERR]vfe_device_regulator_get error at input_num = 1
[  104.593000] [VFE]V4L2 device registered as (null)
[  104.598173] [VFE]vfe_runtime_suspend
[  104.602228] [VFE]..........................vfe clk close!.......................
[  104.616673] [VFE]probe_work_handle end!

驱动加载出现些问题，改驱动

（4）驱动修改如下

删除flvdd

关闭csi0_dev1

驱动加载正常如下：

[   38.626013] [VFE]cci probe end cci_sel = 0!
[   38.631032] [VFE]cci_init end
# insmod tp9950.ko 
# insmod vfe_v4l2.ko 
[   47.275979] [VFE]Welcome to Video Front End driver
[   47.281644] [VFE]csi0 probe end!
[   47.285597] [VFE]csi_init end
[   47.289679] [ISP] isp platform_id = 3!
[   47.293931] [VFE]isp0 probe end!
[   47.297837] [VFE]sunxi_isp_platform_register end
[   47.303322] [VFE]mipi_init end
[   47.306654] [VFE]flash_init end
[   47.311851] [VFE]pdev->id = 0
[   47.315086] [VFE]dev->cci_sel = 0
[   47.318698] [VFE]dev->csi_sel = 0
[   47.322541] [VFE]dev->mipi_sel = 0
[   47.326249] [VFE]dev->isp_sel = 0
[   47.329875] [VFE_WARN]fetch csi0_dev0_twi_id from device_tree failed
[   47.337085] [VFE_WARN]fetch csi0_dev0_afvdd from device_tree failed
[   47.344050] [VFE_WARN]fetch csi0_dev0_afvdd_vol from device_tree failed
[   47.351401] [VFE_WARN]fetch csi0_dev0_power_en from device_tree failed
[   47.358555] [VFE_WARN]fetch csi0_dev0_flash_en from device_tree failed
[   47.365930] [VFE_WARN]fetch csi0_dev0_flash_mode from device_tree failed
[   47.373375] [VFE_WARN]fetch csi0_dev0_flvdd from device_tree failed
[   47.380340] [VFE_WARN]fetch csi0_dev0_af_pwdn from device_tree failed
[   47.387980] [VFE]vfe_init end
[   47.391291] [VFE]probe_work_handle start!
[   47.395871] [VFE]vfe_runtime_resume
# [   47.411931] [VFE]..........................vfe clk open!.......................
[   47.420069] [VFE]v4l2 subdev register input_num = 0
[   47.425574] [VFE]vfe sensor detect start! input_num = 0
[   47.431472] [VFE_WARN]NOT found this item:  tp9950, you can add this sensor in the sensor_list_t!
[   47.441325] [VFE]Sub device register "tp9950" i2c_addr = 0x44 start!
[   47.448262] [VFE]v4l2_device_register_subdev return 0
[   47.454003] [VFE]registered sensor subdev is OK!
[   47.459037] [VFE]Check sensor!
[   47.475237] [TW2866]CSI_SUBDEV_PWR_ON!
[   47.480632] [VFE]mclk on
[   47.551459] [TW2866]sensor_init
[   47.555175] [VFE CCI_0 ERR] Status error at addr_8bit = 44, wr_flag = 1, val = ff
[   47.563723] [VFE CCI_0 ERR] Status error at addr_8bit = 44, wr_flag = 1, val = ff
[   47.572264] [VFE CCI_0 ERR] Status error at addr_8bit = 44, wr_flag = 1, val = ff
[   47.580577] tp9950 sensor read retry=2
[   47.584663] [TW2866]error at sensor_detect
[   47.589129] [TW2866]chip found is not an target chip.
[   47.594876] [TW2866]CSI_SUBDEV_PWR_OFF!
[   47.599057] [VFE]mclk off
[   47.638470] [VFE]vfe sensor subdev unregister!
[   47.643407] [VFE]Sub device register "tp9950" failed!
[   47.648918] [VFE_ERR]vfe sensor register check error at input_num = 0
[   47.656178] [VFE]V4L2 device registered as (null)
[   47.661442] [VFE]vfe_runtime_suspend
[   47.665339] [VFE]..........................vfe clk close!.......................
[   47.679781] [VFE]probe_work_handle end!

驱动里面有设备检测机制，检测不到就注销设备，所以看不到video0