一、閃光燈基本原理
工作模式
Camera flash led分flash和torch兩種模式。
- flash:
拍照時上光燈瞬間亮一下,電流比較大,目前是1000mA,最大電流不能超過led最大承受能力
- torch:
只用于錄video或者拿led當手電筒的情況,電流不能太大,
flash開啟需要先從torch過渡,這樣電流可以慢慢增大,減少沖擊。
二、驅(qū)動移植
1. 硬件電路
dgm3141總體來說比較簡單,只有兩個引腳用于控制:FLASH_EN、FLASH/TORCH。
- FLASH_EN
閃光燈使能引腳。
- FLASH/TORCH
此處led flash和TORCH功能共用了同一個gpio。
“注意: 有的攝像頭是通過pwm來控制閃光燈,具體問題具體分析,不要教條
”
2. 設(shè)備樹
瑞芯微sdk中沒有專門針對sgm3141的驅(qū)動,網(wǎng)上搜了一大圈也沒有搜到,很多閃光燈都是基于I2C接口,通過I2C來設(shè)置上光燈的工作模式,好在sdk中有類似的芯片rgb13h驅(qū)動,該驅(qū)動只有一個引腳用于閃光燈,和我們的功能很類似。
參考驅(qū)動文件:leds-rgb13h.c
sgm3141設(shè)備樹節(jié)點
flash_sgm3141:flash-sgm3141 { status = "okay"; compatible = "sgmicro,sgm3141"; label = "gpio-flash"; pinctrl-names = "default"; pinctrl-0 = <&flash_led_gpios>; led-max-microamp = <20000>; flash-max-microamp = <20000>; flash-max-timeout-us = <1000000>; strobe-gpios = <&gpio3 RK_PC7 GPIO_ACTIVE_HIGH>; enable-gpios = <&gpio3 RK_PD0 GPIO_ACTIVE_HIGH>; rockchip,camera-module-index = <0>; rockchip,camera-module-facing = "back"; }; ov13850: ov13850@10 { …… flash-leds = <&flash_sgm3141>; …… };
pinctrl設(shè)置:
&pinctrl { …… flash-led { flash_led_gpios: flash-led { rockchip,pins = /* flash led enable*/ <3 RK_PD0 RK_FUNC_GPIO &pcfg_pull_none>, <3 RK_PC6 RK_FUNC_GPIO &pcfg_pull_none>; }; }; …… };
@drivers/leds/Makefileobj-y += sgm3141.o
驅(qū)動模塊直接寫死,不羅嗦
三、xml
要app支持閃光燈,還需要修改xml文件,打開該功能
@hardware/rockchip/camera/etc/camera/camera3_profiles.xml@hardware/rockchip/camera/etc/camera/camera3_profiles_rk356x.xml<flash.info.available value="TRUE"/>
這樣,打開app就可以看到上光燈的按鈕。
四、拓撲結(jié)構(gòu)
拓撲結(jié)構(gòu)中entity
rk3568_r:/ # media-ctl -d /dev/media0 -p……- entity 70: m01_f_ov5648 4-0036 (1 pad, 1 link) type V4L2 subdev subtype Sensor device node name /dev/v4l-subdev3 pad0: Source [fmt:SBGGR10/2592x1944] -> "rockchip-csi2-dphy0":0 []- entity 74: m00_b_ov13850 4-0010 (1 pad, 1 link) type V4L2 subdev subtype Sensor device node name /dev/v4l-subdev4 pad0: Source [fmt:SBGGR10/4224x3136] -> "rockchip-csi2-dphy0":0 []- entity 78: m00_b_gpio-flash (0 pad, 0 link) type V4L2 subdev subtype Flash device node name /dev/v4l-subdev5
- 攝像頭:
m00_b_ov13850、m01_f_ov5648
- 閃光燈:
m00_b_gpio-flash,v4l2子設(shè)備/dev/v4l-subdev5
第4個字母b表示后置攝像頭。
五、調(diào)試
驅(qū)動會通過sysfs創(chuàng)建文件節(jié)點
rk3568_r:/sys/class/leds/gpio-flash # lsbrightness flash_strobe max_brightness power triggerdevice flash_timeout max_flash_timeout subsystem uevent
- 亮滅燈
亮燈rk3568_r:/sys/class/leds/gpio-flash # echo 1 > brightnessecho 1 > brightness滅燈1|rk3568_r:/sys/class/leds/gpio-flash # echo 0 > brightnessecho 0 > brightness
操作對應(yīng)函數(shù)調(diào)用關(guān)系
[ 374.302386] Call trace: [ 374.302428] dump_backtrace+0x0/0x178 [ 374.302471] show_stack+0x14/0x20 [ 374.302518] dump_stack+0x94/0xb4 [ 374.302560] sgm3141_led_brightness_set+0x18/0x40 [ 374.302592] led_set_brightness_nopm+0x14/0x48 [ 374.302624] led_set_brightness+0x50/0x80 [ 374.302662] brightness_store+0x74/0xc8 [ 374.302691] dev_attr_store+0x18/0x28 [ 374.302728] sysfs_kf_write+0x48/0x58 [ 374.302759] kernfs_fop_write+0xf4/0x220 [ 374.302793] __vfs_write+0x34/0x158 [ 374.302810] vfs_write+0xb0/0x1d0 [ 374.302828] ksys_write+0x64/0xe0 [ 374.302860] __arm64_sys_write+0x14/0x20 [ 374.302904] el0_svc_common.constprop.0+0x64/0x178 [ 374.302947] el0_svc_handler+0x28/0x78 [ 374.302984] el0_svc+0x8/0xc [ 425.607850] healthd: battery l=50 v=3 t=2.6 h=2 st=3 fc=100 chg=au [ 437.663757] CPU: 3 PID: 1727 Comm: sh Not tainted 4.19.232 #326 [ 437.663869] Hardware name: Rockchip RK3568 EVB1 DDR4 V10 Board (DT)
- 閃燈
rk3568_r:/sys/class/leds/gpio-flash # echo 1 > flash_strobeecho 1 > flash_strobe
操作對應(yīng)函數(shù)調(diào)用關(guān)系
[ 492.026239] Call trace: [ 492.026291] dump_backtrace+0x0/0x178 [ 492.026320] show_stack+0x14/0x20 [ 492.026354] dump_stack+0x94/0xb4 [ 492.026391] sgm3141_led_flash_strobe_set+0x24/0x78 [ 492.026453] flash_strobe_store+0x88/0xd8 [ 492.026517] dev_attr_store+0x18/0x28 [ 492.026571] sysfs_kf_write+0x48/0x58 [ 492.026620] kernfs_fop_write+0xf4/0x220 [ 492.026683] __vfs_write+0x34/0x158 [ 492.026733] vfs_write+0xb0/0x1d0 [ 492.026784] ksys_write+0x64/0xe0 [ 492.026833] __arm64_sys_write+0x14/0x20 [ 492.026867] el0_svc_common.constprop.0+0x64/0x178 [ 492.026912] el0_svc_handler+0x28/0x78 [ 492.026966] el0_svc+0x8/0xc [ 494.218112] CPU: 2 PID: 1727 Comm: sh Not tainted 4.19.232 #326 [ 494.218218] Hardware name: Rockchip RK3568 EVB1 DDR4 V10 Board (DT)
“為方便查看驅(qū)動回調(diào)函數(shù)調(diào)用順序,可以在下面3個回調(diào)函數(shù)入口增加dump_stack(), sgm3141_led_brightness_set() sgm3141_led_flash_strobe_set() sgm3141_set_ctrl()
”
六、app 測試驅(qū)動 log分析
1. 上電加載驅(qū)動log
rk3568_r:/ # dmesg | grep sgm3141dmesg | grep sgm3141[ 0.853883] sgm3141-flash flash-sgm3141: driver version: 00.01.01[ 0.853956] sgm3141-flash flash-sgm3141: Unable to get pwm device
2. 打開攝像頭
打開攝像頭功能,app調(diào)用ioctl命令如下:
- V4L2_CID_FLASH_LED_MODE :app 設(shè)置led mode為 V4L2_FLASH_LED_MODE_FLASH(1)
- V4L2_CID_FLASH_TIMEOUT :設(shè)置超時時間
- V4L2_CID_FLASH_STROBE_STOP :停止閃光
[ 36.213220] sgm3141 V4L2_CID_FLASH_LED_MODE 1[ 36.213250] sgm3141_set_ctrl(),376[ 36.213256] sgm3141_set_output(),78 0[ 36.213265] sgm3141_led_flash_strobe_set(),166 state=1[ 36.213281] sgm3141_set_output(),78 1[ 36.213298] sgm3141 V4L2_CID_FLASH_TIMEOUT[ 36.213300] sgm3141_set_ctrl(),412[ 36.213308] sgm3141_led_flash_timeout_set(),195 timeout=500000[ 36.213318] sgm3141 V4L2_CID_FLASH_STROBE_STOP 1[ 36.213323] sgm3141_set_ctrl(),406[ 36.213327] sgm3141_led_flash_strobe_set(),166 state=0[ 36.213332] sgm3141_set_output(),78 0[ 36.213461] sgm3141_timeout_work(),117
3. 拍照
拍照功能,app調(diào)用ioctl命令如下:
- V4L2_CID_FLASH_LED_MODE :設(shè)置led mod為 V4L2_FLASH_LED_MODE_TORCH(2),并點燈
- V4L2_CID_FLASH_LED_MODE:到達指定超時時間(2.7秒),設(shè)置led mod為 V4L2_FLASH_LED_MODE_NONE 0
- V4L2_CID_FLASH_LED_MODE:在此設(shè)置led mod為V4L2_FLASH_LED_MODE_FLASH(1)
- V4L2_CID_FLASH_STROBE_STOP:停止閃光
[ 90.246203] sgm3141 V4L2_CID_FLASH_LED_MODE 2[ 90.246251] sgm3141_set_ctrl(),376[ 90.246262] sgm3141_set_output(),78 0[ 90.246277] sgm3141_set_output(),78 1[ 92.902746] sgm3141 V4L2_CID_FLASH_LED_MODE 0[ 92.902775] sgm3141_set_ctrl(),376[ 92.902781] sgm3141_set_output(),78 0[ 93.034903] sgm3141 V4L2_CID_FLASH_LED_MODE 1[ 93.034929] sgm3141_set_ctrl(),376[ 93.034934] sgm3141_set_output(),78 0[ 93.034943] sgm3141_led_flash_strobe_set(),166 state=1[ 93.034959] sgm3141_set_output(),78 1[ 93.034977] sgm3141 V4L2_CID_FLASH_STROBE_STOP 1[ 93.034988] sgm3141_set_ctrl(),406[ 93.034993] sgm3141_led_flash_strobe_set(),166 state=0[ 93.035002] sgm3141_set_output(),78 0[ 93.035058] sgm3141_timeout_work(),117
從log可以看出,app拍照的時候,閃光燈操作是通過v4l2下發(fā)的命令,
而我們直接操作宏dev_attr_store創(chuàng)建的文件節(jié)點則是通過在sysfs文件節(jié)點(brightness flash_strobe)直接調(diào)用到操作函數(shù)。
4. 退出攝像頭
[ 317.882459] sgm3141 V4L2_CID_FLASH_LED_MODE 0[ 317.882522] sgm3141_set_ctrl(),376[ 317.882532] sgm3141_set_output(),78 0
七、驅(qū)動獲取
一口君修改過的驅(qū)動已經(jīng)上傳到gitee,獲取地址:https://gitee.com/yikoulinux/sgm3141