imx7ulp-backlight

晖蓝 — Thu, 07 Jan 2021 05:09:43 GMT

蒋工，LCD屏背光默认改成低电平不生效。上电默认是高电平，需要改成默认低电平。不然会出现闪屏现象。

我的修改如下：dts和fbtft_device.c

pinctrl_lpspi2: lpspi2grp { fsl,pins = < IMX7ULP_PAD_PTE4__LPSPI2_SIN 0x0 IMX7ULP_PAD_PTE5__LPSPI2_SOUT 0x0 IMX7ULP_PAD_PTE6__LPSPI2_SCK 0x0 >; }; pinctrl_lpspi2_cs: lpspi2cs { fsl,pins = < IMX7ULP_PAD_PTE7__PTE7 0x10003 >; }; pinctrl_st7789v: st7789vgrp { fsl,pins = < IMX7ULP_PAD_PTE1__PTE1 0x10003 IMX7ULP_PAD_PTE14__PTE14 0x10003 IMX7ULP_PAD_PTE13__PTE13 0x10003 //backlight >; }; &lpspi2 { #address-cells = <1>; #size-cells = <0>; pinctrl-names = "default", "sleep"; pinctrl-0 = <&pinctrl_lpspi2 &pinctrl_lpspi2_cs>; cs-gpios = <&gpio_pte 7 GPIO_ACTIVE_LOW>; //pinctrl-1 = <&pinctrl_lpspi2>; status = "okay"; sd2088@0 { compatible = "sitronix,st7789v"; reg = <0>; // add pin ctrl pinctrl-names = "default"; pinctrl-0 = <&pinctrl_st7789v>; spi-max-frequency = <24000000>; rotate = <0>; bgr; fps = <15>; buswidth = <8>; reset-gpios = <&gpio_pte 01 GPIO_ACTIVE_LOW>; dc-gpios = <&gpio_pte 14 GPIO_ACTIVE_LOW>; led-gpios = <&gpio_pte 13 GPIO_ACTIVE_LOW>;//backlight debug = <0>; }; };

static struct fbtft_device_display displays[] = { { .name = "sd2088", .spi = &(struct spi_board_info) { .modalias = "fb_st7789v", .max_speed_hz = 24000000, .mode = SPI_MODE_0, .platform_data = &(struct fbtft_platform_data) { .display = { .buswidth = 8, .backlight = 1, .init_sequence = cberry28_init_sequence, }, .gpios = (const struct fbtft_gpio []) { { "reset", 65}, { "dc", 78 }, { "led", 77 },//backlight {}, }, .gamma = CBERRY28_GAMMA, } } }, }

Re: imx7ulp-backlight

weidong_sun — Fri, 08 Jan 2021 03:03:50 GMT

你好，晖蓝，

你提到的蒋工，是我的同事Maggie Jiang吗？我会转告她！

你提到的背光LED控制电路，确实是这样的，开始的时候，恒流电源芯片的enable端需要保持LOW电平，不能电路上拉高。一般情况下，可以PWM信号，直接控制恒流源的EN脚，这样就可以随着PWM波的占空比调整，就可以控制LED的亮度了。

Have a nice day!

B.R,

Weidong

Re: imx7ulp-backlight

terry_lv — Mon, 11 Jan 2021 07:02:30 GMT

Hi,

Confirmed by customer that it is a hardware issue.

Now the issue is fixed.

Thanks!

Regards

Terry

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