On Mon, Mar 17, 2014 at 2:52 PM,  <[email protected]> wrote:
> The BBB seems to auto-detect if an SD is loaded and boots from there;
> otherwise it boots from eMMC, at least mine does.
> So I have modified /boot/uboot/uEnv.txt while running on the SD to start up
> with HDMI disabled and PWM and UART1 enabled:
>
> root@debian:~# cat /boot/uboot/uEnv.txt
> kernel_file=zImage
> initrd_file=initrd.img
> initrd_high=0xffffffff
> fdt_high=0xffffffff
>
> #Video: Uncomment to override:
> #kms_force_mode=video=HDMI-A-1:1024x768@60
>
> ##Enable systemd
> #systemd=quiet init=/lib/systemd/systemd
>
> ##BeagleBone Cape Overrides
> ##Note: On the BeagleBone Black, there is also an uEnv.txt in the eMMC, so
> if these changes do not seem to be makeing a difference...
>
> ##BeagleBone Black:
> ##Disable HDMI/eMMC
> #optargs=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN,BB-BONE-EMMC-2G
>
> console=ttyO0,115200n8
>
> mmcroot=/dev/mmcblk0p2 ro
> mmcrootfstype=ext4 rootwait fixrtc
>
> loadkernel=load mmc ${mmcdev}:${mmcpart} 0x80300000 ${kernel_file}
> loadinitrd=load mmc ${mmcdev}:${mmcpart} 0x81600000 ${initrd_file}; setenv
> initrd_size ${filesize}
> loadfdt=load mmc ${mmcdev}:${mmcpart} 0x815f0000 /dtbs/${fdtfile}
>
> boot_ftd=run loadkernel; run loadinitrd; run loadfdt
>
> device_args=run expansion_args; run mmcargs
> mmcargs=setenv bootargs console=${console} ${optargs} ${kms_force_mode}
> root=${mmcroot} rootfstype=${mmcrootfstype} ${expansion} ${systemd}
>
> expansion_args=setenv expansion ip=${ip_method}
> uenvcmd=run boot_ftd; run device_args; bootz 0x80300000
> 0x81600000:${initrd_size} 0x815f0000
> #Next line added to preserve pwm at bootup
> optargs=quiet drm.debug=7 capemgr.enable_partno=am33xx_pwm,bone_pwm_P9_21
> #Next line added to preserve UART1 (ttyO1) at boot time
> optargs=quiet drm.debug=7 capemgr.enable_partno=BB-UART1
> #Disable HDMI only
> optargs=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN
>
>
> But this is what I get on boot:
>
> root@debian:~# cat /sys/devices/bone_capemgr.*/slots
>  0: 54:PF---
>  1: 55:PF---
>  2: 56:PF---
>  3: 57:PF---
>  4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
>  5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
>  6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN
>
> There's no pwm, no uart and ole HDMI's still there. Can anyone explain that?
> Does the uEnv.txt file require things in a special order?

Well, it did exactly what you told it to do. The last definition:
"optargs=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN"
disabled HDMI/HDMIN. The two previous definitions of "optargs" were
ignored, as the variable optargs was overwritten by the last define.
Does that make sense? It's simple variable defines..

Regards,

-- 
Robert Nelson
http://www.rcn-ee.com/

-- 
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