4.3. Camera
參考文件：
1) 80-NA157-22_PRESENTATION- MSM8974-APQ8074-MSM8X26-APQ8084 LINUX CAMERA OVERVIEW.pdf

2) 80-NE717-1_MSM8974-APQ8074-MSM8X26 LINUX CAMERA SOFTWARE DESIGN DOCUMENT.pdf

3) 80-NU323-2_Multimedia Driver Development and Bringup Guide - Camera.pdf

4) 80-NL239-33_LINUX CAMERA DEBUGGING GUIDE.pdf

4.3.1. Camera軟體架構

4.3.2. Kernel驅動
1) 增加dts配置
qcom,[email protected] {//back camera
compatible = “samsung,s5k3m2”;
reg = <0x5a>;
qcom,slave-id = <0x5a 0x0000 0x30d2>;
qcom,csiphy-sd-index = <0>;
qcom,csid-sd-index = <0>;
qcom,mount-angle = <90>;
qcom,sensor-name = “s5k3m2_f13s01k”;
qcom,actuator-src = <&actuator0>;
qcom,led-flash-src = <&led_flash0>;
cam_vdig-supply = <&pm8941_l3>;
cam_vana-supply = <&pm8941_l17>;
cam_vio-supply = <&pm8941_lvs2>;
cam_vaf-supply = <&pm8941_l23>;
qcom,cam-vreg-name = “cam_vdig”, “cam_vio”, “cam_vana”,
“cam_vaf”;
qcom,cam-vreg-type = <0 1 0 0>;
qcom,cam-vreg-min-voltage = <1225000 0 2850000 3000000>;
qcom,cam-vreg-max-voltage = <1225000 0 2850000 3000000>;
qcom,cam-vreg-op-mode = <105000 0 80000 100000>;
qcom,gpio-no-mux = <0>;
gpios = <&msmgpio 15 0>,
<&msmgpio 90 0>;
qcom,gpio-reset = <1>;
qcom,gpio-req-tbl-num = <0 1>;
qcom,gpio-req-tbl-flags = <1 0>;
qcom,gpio-req-tbl-label = “CAMIF_MCLK”,
“CAM_RESET1”;
qcom,gpio-set-tbl-num = <1 1>;
qcom,gpio-set-tbl-flags = <0 2>;
qcom,gpio-set-tbl-delay = <1 1000>;
qcom,csi-lane-assign = <0x4320>;
qcom,csi-lane-mask = <0x1F>;
qcom,sensor-position = <0>;
qcom,sensor-mode = <0>;
qcom,cci-master = <0>;
};
2) 增加驅動檔案
kernel/drivers/media/platform/msm/camera_v2/sensor
複製一個原有camera的驅動檔案並改名，比如ov8865.c改為s5k3l2.c。開啟s5k3l2.c，把裡面的ov8865改成s5k3l2, OV8865改為S5K3L2。
在Makefile里加上obj-$(CONFIG_S5K3L2) += s5k3l2.o
s5k3l2.c裡需要改動的是上電序列，需要根據原理圖來配置
static struct msm_sensor_power_setting s5k3l2_power_setting[] = {
{
.seq_type = SENSOR_VREG,
.seq_val = CAM_VIO,
.config_val = 0,
.delay = 1,
},
{
.seq_type = SENSOR_VREG,
.seq_val = CAM_VANA,
.config_val = 0,
.delay = 1,
},
{
.seq_type = SENSOR_VREG,
.seq_val = CAM_VDIG,
.config_val = 0,
.delay = 1,
},
{
.seq_type = SENSOR_VREG,
.seq_val = CAM_VAF,
.config_val = 0,
.delay = 5,
},
{
.seq_type = SENSOR_GPIO,
.seq_val = SENSOR_GPIO_STANDBY,
.config_val = GPIO_OUT_LOW,
.delay = 1,
},
{
.seq_type = SENSOR_GPIO,
.seq_val = SENSOR_GPIO_RESET,
.config_val = GPIO_OUT_LOW,
.delay = 5,
},
{
.seq_type = SENSOR_GPIO,
.seq_val = SENSOR_GPIO_AF_PWDM,
.config_val = GPIO_OUT_LOW,
.delay = 5,
},
{
.seq_type = SENSOR_GPIO,
.seq_val = SENSOR_GPIO_STANDBY,
.config_val = GPIO_OUT_HIGH,
.delay = 5,
},
{
.seq_type = SENSOR_GPIO,
.seq_val = SENSOR_GPIO_RESET,
.config_val = GPIO_OUT_HIGH,
.delay = 10,
},
{
.seq_type = SENSOR_GPIO,
.seq_val = SENSOR_GPIO_AF_PWDM,
.config_val = GPIO_OUT_HIGH,
.delay = 5,
},
{
.seq_type = SENSOR_CLK,
.seq_val = SENSOR_CAM_MCLK,
.config_val = 24000000,
.delay = 10,
},
{
.seq_type = SENSOR_I2C_MUX,
.seq_val = 0,
.config_val = 0,
.delay = 0,
},
};
3) 除錯
在檔案：kernel/drivers/media/platform/msm/camera_v2/sensor/msm_sensor.c
開啟這個巨集：#define CONFIG_MSMB_CAMERA_DEBUG
檢查開機時kernel log
CDBG(“%s: read id: %x expected id %x:\n”, func

, chipid,
slave_info->sensor_id);
看與camera的i2c通訊是否成功。
4.3.3. user space驅動
1) 增加程式碼
vendor/qcom/proprietary/mm-camera/mm-camera2/media-controller/modules/sensors/sensor_libs/ 裡增加一個驅動資料夾s5k3l2，裡面有兩個檔案：Android.mk和s5k3l2_lib.c
一般來說高通會提供驅動，模組廠也會提供相應的驅動。
把驅動加入進去，編譯成so，然後push到手機裡。或者整個編譯成system.img，刷入手機。

有的時候，我們發現系統裡找不到camera應用的圖示。這是由於系統第一次啟動時，後攝的kernel驅動沒有準備好。
如何解決：
➢ Kernel驅動除錯好後，重新刷userdata.img。讓系統重新初始化。
➢ adb shell am start -n com.android.camera/com.android.camera.Camera package和activity的名字需要和手機裡的應用匹配，不一定是上面這個名字。
➢ 安裝其它的camera應用。

2) 除錯
開啟camera應用，看看影象預覽是否成功。如果不成功，需要除錯。
➢ 在程式碼裡開啟除錯開關
vendor/qcom/proprietary/mm-camera/mm-camera2/media-controller/modules/sensors/sensors/sensor.c
#define SLOW SERR
SLOW(“lib_name %s”, lib_name); 可以看到是否正確庫被呼叫。
➢ Lane配置
qcom,csi-lane-assign = <0x4320>; 這是8974平臺的值，其它平臺不一樣
qcom,csi-lane-mask = <0x1F>; 0x1F for 4lane, 0x7 for 2 lane, 0x3 for 1 lane
這個配置每個平臺不一樣。
大部分情況下，到這裡基本就調通了，可以預覽了。如果一直調不調，有可能是模組硬體有問題，需要和模組廠一起跳。

3) 從頭建立lib.c檔案
在某些情況下，如果不能得到驅動檔案，需要根據晶片廠商的資料手冊和高通的文件來自己寫lib.c
4.3.4. 閃光燈
這是系統圖自帶閃光燈的配置
qcom,[email protected] {
status = “okay”;
pm8941_flash0: qcom,flash_0 {
qcom,max-current = <1000>;
qcom,default-state = “off”;
qcom,headroom = <3>;
qcom,duration = <1280>;
qcom,clamp-curr = <200>;
qcom,startup-dly = <3>;
qcom,safety-timer;
label = “flash”;
linux,default-trigger =
“flash0_trigger”;
qcom,id = <1>;
linux,name = “led:flash_0”;
qcom,current = <625>;
};
使用時做camera的配置檔案里加上就行。
qcom,led-flash-src = <&led_flash0>;
4.3.5. 對焦馬達
Kernel裡面的驅動都是一樣的，主要的改動在user space
vendor/qcom/proprietary/mm-camera/mm-camera2/media-controller/modules/sensors/actuator_libs
vendor/qcom/proprietary/mm-camera/mm-camera2/media-controller/modules/sensors/actuators
4.3.6. Tuning
馬達，閃光燈，拍照效果都是要Tuning的。但是需要實驗室環境來做。
注意：在馬達的核心驅動里加上過多log，可能導致馬達不能正常對焦。