On Thu, Feb 27, 2020 at 9:14 AM Faby <[email protected]> wrote: > > Hi, > I would like to set low the logic level on the P9_11 during the power on, so > before the linux kernel has bees loaded. > I do not have experince with tree device and boot loader so I am here to ask > your help. >>> >>> For what I was able to discover and collecting fragmentated informations, I >>> have to modify the file >>> "/boot/dtbs/4.14.71-bone-rt-r17/am335x-boneblack-uboot.dtb". > > This file should be responsable for give the earlier informations during the > power on start up of the system. > I have decompiled this file and added: > > pinmux_P9_11_gpio_pd_pin { > pinctrl-single,pins = <0x70 0x27>; > phandle = <0x180>; > }; > P9_11_pinmux { > compatible = "bone-pinmux-helper"; > status = "okay"; > pinctrl-names = "default", "gpio", "gpio_pu", "gpio_pd", "gpio_input", > "uart"; > pinctrl-0 = <0x17d>; > pinctrl-1 = <0x17e>; > pinctrl-2 = <0x17f>; > pinctrl-3 = <0x180>; > pinctrl-4 = <0x181>; > pinctrl-5 = <0x182>; > }; > P9_11 { > gpio-name = "P9_11"; > gpio = <0x35 0x1e 0x0>; > output; > dir-changeable; > }; > > So, I guess, the system in power up will be able to set up and drive this PIN. > > Due to the lack of specific knowledge in this area now I am stuck, I don't > know how to precede.
Use gpio-hog: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/am335x-bonegreen-wireless.dts?h=v5.6-rc3#n121 Regards, -- Robert Nelson https://rcn-ee.com/ -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAOCHtYiyR%3D62ta-Po4OM1_2ug6DHhfr-Df1R%2Bf_5O-ctoNDxuA%40mail.gmail.com.
