UART2 don't work on BBB rev C - kernel 4.4.54

[Vinicius]

I can't enable UART2, no tx, on BBB rev C, with kernel

4.4.54-ti-rt-r93
BeagleBoard.org Debian Image 2017-03-19

bellow, a sequence of commands

export SLOTS=/sys/devices/platform/bone_capemgr/slots
echo 'BB-UART2' > $SLOTS

I get this error:

[  935.084183] bone_capemgr bone_capemgr: slot #11: BB-UART2 conflict P9.21 (#5:BB-UART2)
[  935.107137] bone_capemgr bone_capemgr: slot #11: Failed verification

root@beaglebone:/home/debian# cat $SLOTS
 0: PF----  -1
 1: PF----  -1
 2: PF----  -1
 3: PF----  -1
 4: P-O-L-   0 Override Board Name,00A0,Override Manuf,BB-UART1
 5: P-O-L-   1 Override Board Name,00A0,Override Manuf,BB-UART2
 6: P-O-L-   3 Override Board Name,00A0,Override Manuf,BB-UART4
 7: P-O-L-   2 Override Board Name,00A0,Override Manuf,BB-SPIDEV1
 8: P-O-L-   4 Override Board Name,00A0,Override Manuf,BB-I2C1
 9: P-O-L-   5 Override Board Name,00A0,Override Manuf,BB-I2C2

bellow, the contents of /boot/uEnv.txt:

#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0

uname_r=4.4.54-ti-rt-r93
#uuid=
#dtb=

##BeagleBone Black/Green dtb's for v4.1.x (BeagleBone White just works..)

##BeagleBone Black: HDMI (Audio/Video) disabled:
dtb=am335x-boneblack-emmc-overlay.dtb

##BeagleBone Black: eMMC disabled:
#dtb=am335x-boneblack-hdmi-overlay.dtb

##BeagleBone Black: HDMI Audio/eMMC disabled:
#dtb=am335x-boneblack-nhdmi-overlay.dtb

##BeagleBone Black: HDMI (Audio/Video)/eMMC disabled:
#dtb=am335x-boneblack-overlay.dtb

##BeagleBone Black: wl1835
#dtb=am335x-boneblack-wl1835mod.dtb

##BeagleBone Green: eMMC disabled
#dtb=am335x-bonegreen-overlay.dtb

###U-Boot Overlays###
###Documentation: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Overlays
###Master Enable
#enable_uboot_overlays=1
###Overide capes with eeprom
#uboot_overlay_addr0=/lib/firmware/<file0>.dtbo
#uboot_overlay_addr1=/lib/firmware/<file1>.dtbo
#uboot_overlay_addr2=/lib/firmware/<file2>.dtbo
#uboot_overlay_addr3=/lib/firmware/<file3>.dtbo
###Custom Cape
#dtb_overlay=/lib/firmware/<file4>.dtbo
###Disable auto loading of virtual capes (emmc/video/wireless)
#disable_uboot_overlay_emmc=1
#disable_uboot_overlay_video=1
#disable_uboot_overlay_audio=1
#disable_uboot_overlay_wireless=1
###Cape Universal Enable
#enable_uboot_cape_universal=1
###U-Boot fdt tweaks...
#uboot_fdt_buffer=0x60000
###U-Boot Overlays###

cmdline=coherent_pool=1M net.ifnames=0 quiet

#In the event of edid real failures, uncomment this next line:
#cmdline=coherent_pool=1M net.ifnames=0 quiet cape_universal=enable video=HDMI-A-1:1024x768@60e

##Example v3.8.x
#cape_disable=capemgr.disable_partno=
#cape_enable=capemgr.enable_partno=

##Example v4.1.x
#cape_disable=bone_capemgr.disable_partno=
cape_enable=bone_capemgr.enable_partno=BB-UART1,BB-UART2,BB-UART4,BB-SPIDEV1,BB-I2C1,BB-I2C2

##enable Generic eMMC Flasher:
##make sure, these tools are installed: dosfstools rsync
#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh

uuid=05ece140-c557-48f5-b454-2ca9a1b8ed34

thanks for any help!!!

Vinicius

[Vinicius]

After a few attempts, I found that by positioning BB-UART2, on the line below on /boot/uEnv.txt, , after BB-SPIDEV1, UART2 transmits!

Cape_enable = bone_capemgr.enable_partno = BB-SPIDEV1,BB-UART1,BB-UART2,BB-UART4,BB-I2C1

I'm confused by this behavior, could anyone explain this?

thanks for all

Vinicius

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[Robert Nelson]

On Sun, Apr 9, 2017 at 5:43 PM, Vinicius <sdmi...@uol.com.br> wrote:
> After a few attempts, I found that by positioning BB-UART2, on the line
> below on /boot/uEnv.txt, , after BB-SPIDEV1, UART2 transmits!
>
> Cape_enable = bone_capemgr.enable_partno =
> BB-SPIDEV1,BB-UART1,BB-UART2,BB-UART4,BB-I2C1
>
> I'm confused by this behavior, could anyone explain this?

kernel overlays are racy and can be hit and miss with a large number
of overlays.

Just convert to using U-Boot Overlays:

http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Overlays

Regards,

--
Robert Nelson
https://rcn-ee.com/

[S&DeMario]

Thank you, Robert, I will see


Regards

Vinicius