/dev/fb0 vertical refresh is running at 120Hz

[jwinarske]

Rocko / PICO-PI-IMX7

root@pico-imx7:~# cat /sys/class/graphics/fb0/modes U:480x272p-120 U:480x272i-120

Should be no more than 60Hz, or it's burning power for no good reason...

[richard-hu]

@jwinarske

For PICO-IMX7, the default panel is 5-inch 800x480 parallel LCD in Yocto 2.4 release image:

ftp://ftp.technexion.net/demo_software/pico-imx7-sd/pico-imx7_pico-pi_yocto-2.4-qt5_sdcard-preview_QCA9377_lcd-800x480_20181102.zip

The frequency i get is 53Hz:

root@pico-imx7:~# cat /sys/class/graphics/fb0/modes
U:800x480p-53
U:800x480i-53

Please check the settings of device node lcdif in arch/arm/boot/dts/imx7d-pico.dtsi:

&lcdif {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_lcdif_dat
             &pinctrl_lcdif_ctrl>;
    lcd-supply = <&lcd_on>;
    display = <&display0>;
    status = "okay";

    display0: display {
        bits-per-pixel = <32>;
        bus-width = <24>;

        display-timings {
            native-mode = <&timing0>;
            timing0: timing0 {
                clock-frequency = <33260000>;
                hactive = <800>;
                vactive = <480>;
                hback-porch = <11>;
                hfront-porch = <11>;
                vback-porch = <12>;
                vfront-porch = <11>;
                hsync-len = <46>;
                vsync-len = <210>;
                hsync-active = <0>;
                vsync-active = <0>;
                de-active = <1>;
                pixelclk-active = <1>;
                interlaced =  <0>;
            };
        };
    };
};

drivers/video/fbdev/mxsfb.c gets the information from lcdif to calculate frequency. (I didn't really dig into it. )

BR,

Richard

[jwinarske]

Okay I'm all set. The timing was set wrong in both boot and kernel dts. Thanks!