[Samsung Captivate Glide] nemo.:
Thanks for the tip but the permissions look alright on my side:

root@android:/etc # ls -al /efs/nv*
ls -al /efs/nv*
-rwx------ radio radio 2652 2012-12-13 14:34 nv.log
-rwx------ radio radio 2097152 2013-09-16 20:01 nv_data.bin
-rwx------ radio radio 32 2013-09-16 20:01 nv_data.bin.md5

USB related: I noticed that even the bus goes down from time to time:

<6>[ 6168.154596] tegra-ehci tegra-ehci.1: USB bus 1 deregistered
<6>[ 6168.274795] uhsic_phy_power_off
<6>[ 6168.327053] mif: link_pm_ioctl: 6f30
<6>[ 6168.377901] mif: link_pm_ioctl: 6f30
<6>[ 6168.443167] uhsic_phy_power_on : check clock valid, hsic portsc1 : 0x0c000800
<6>[ 6168.443522] tegra-ehci tegra-ehci.1: Tegra EHCI Host Controller
<7>[ 6168.444586] SELinux: initialized (dev usbfs, type usbfs), not configured for labeling
<6>[ 6168.445112] tegra-ehci tegra-ehci.1: new USB bus registered, assigned bus number 1
<6>[ 6168.484628] tegra-ehci tegra-ehci.1: irq 53, io mem 0xc5004000
<6>[ 6168.504466] tegra-ehci tegra-ehci.1: USB 2.0 started, EHCI 1.00
<6>[ 6168.505250] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
<6>[ 6168.505808] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
<6>[ 6168.506117] usb usb1: Product: Tegra EHCI Host Controller
<6>[ 6168.506653] usb usb1: Manufacturer: Linux 3.1.10-g6938335-dirty ehci_hcd
<6>[ 6168.507192] usb usb1: SerialNumber: tegra-ehci.1
<6>[ 6168.519356] hub 1-0:1.0: USB hub found
<6>[ 6168.519772] hub 1-0:1.0: 1 port detected

Update:

As mentioned by previous posters, baseband loss happens in stock 4.0.4 from time to time

as well. So I restored 4.0.4 from backup as I did every time I fiddled with the 4.3 roms

and experienced said baseband loss on 4.0.4.

The error messages are exactly the same as above, most of the time it was that the

bus could not negotiate the high speed connection with the device (modem). So the

same error is present in 4.0.4 (and possibly in 2.3 as well) but not as acute as in 4.3.

Cutting the power (take out battery, unplug usb), waiting for ~10s, putting everything back

together helped:

<6>[ 7.815195] uhsic_phy_power_on : check clock valid, hsic portsc1 : 0x0c000000
<6>[ 7.815341] tegra-ehci tegra-ehci.1: Tegra EHCI Host Controller
<6>[ 7.815645] tegra-ehci tegra-ehci.1: new USB bus registered, assigned bus number 1
<6>[ 7.870818] tegra-ehci tegra-ehci.1: irq 53, io mem 0xc5004000
<6>[ 7.890781] tegra-ehci tegra-ehci.1: USB 2.0 started, EHCI 1.00
<6>[ 7.890998] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
<6>[ 7.891129] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
<6>[ 7.891254] usb usb1: Product: Tegra EHCI Host Controller
<6>[ 7.891321] usb usb1: Manufacturer: Linux 3.1.10-I927UCLJ3-CL970642 ehci_hcd
<6>[ 7.891446] usb usb1: SerialNumber: tegra-ehci.1
<6>[ 7.892327] hub 1-0:1.0: USB hub found
<6>[ 7.892425] hub 1-0:1.0: 1 port detected
<3>[ 7.942574] tegra_usb_phy_bus_connect: timeout waiting for hsic connect detect
<6>[ 7.960687] mif: link_pm_ioctl: 6f31
<6>[ 7.960859] mif: link_pm_ioctl: 6f33
<6>[ 8.150826] tegra_usb_phy_bus_reset
<6>[ 8.155926] tegra_usb_phy_bus_reset:4:USBMODE:3 USBCMD:10005 USBPORTSC1:8001205 USBSTS:80
<6>[ 8.270802] usb 1-1: new high speed USB device number 2 using tegra-ehci
<6>[ 8.310194] usb 1-1: New USB device found, idVendor=1519, idProduct=0020
<6>[ 8.310278] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
<6>[ 8.310408] usb 1-1: Product: HSIC Device
<6>[ 8.310473] usb 1-1: Manufacturer: Comneon
<6>[ 8.310592] usb 1-1: SerialNumber: 0123456789
<6>[ 8.326237] mif: if_usb_probe: usbdev = 0xdc2d7000
<6>[ 8.326317] mif: if_usb_set_pipe: set 0
<6>[ 8.326441] mif: if_usb_probe: devdata usbdev = 0xdc2d7000
<6>[ 8.326579] mif: if_usb_probe: successfully done
<6>[ 8.328322] mif: if_usb_probe: usbdev = 0xdc2d7000
<6>[ 8.328400] mif: if_usb_set_pipe: set 1
<6>[ 8.328469] mif: if_usb_probe: devdata usbdev = 0xdc2d7000
<6>[ 8.329396] mif: if_usb_probe: successfully done
<6>[ 8.331077] mif: if_usb_probe: usbdev = 0xdc2d7000
<6>[ 8.331207] mif: if_usb_set_pipe: set 2
<6>[ 8.331276] mif: if_usb_probe: devdata usbdev = 0xdc2d7000
<6>[ 8.331382] mif: if_usb_probe: successfully done
<6>[ 8.333050] mif: if_usb_probe: usbdev = 0xdc2d7000
<6>[ 8.333124] mif: if_usb_set_pipe: set 3
<6>[ 8.333630] mif: if_usb_probe: devdata usbdev = 0xdc2d7000
<3>[ 8.333765] mif: link_pm_change_modem_state: set modem state 4
<3>[ 8.333903] mif: io_dev_modem_state_changed: modem state changed. (iod: umts_ipc0, state: 4)
<6>[ 8.333974] mif: if_usb_probe: successfully done
<6>[ 8.461076] mif: link_pm_ioctl: 6f33
<3>[ 8.461248] mif: misc_release: iod = umts_boot0
<3>[ 8.480706] cbd: /main: Boot up process 1done!!!

As you can see, at first the device negotiation failed, but the second attempt succeeded and I got

the SIM unlock dialog.

So this really seems to me to be a timing problem. I don't think this related to heat sensitivity

(works when cold, does not work anymore when warmed up or other way around) as I left the

phone off for a few minutes, booted 4.3 and had the same issues. I also left the phone in a fairly

cold area but nothing changed. Also, heating up by running benchmarks didn't seem to change

anything.

Also, to pin this down to a tegra 2 issue, the Droid X2 has a tegra 2 SoC and there seems to

be a similar problem: droidxforums.com/forum/droid-x2-support/48577-baseband-unknown-random-complete-signal-loss.html and forums.motorola.com/posts/995c36aff8?commentId=548498#548498