[Galaxy Tab S2 General] Lightn1ng:
So, as you know, MANY tab s2 users are having issues getting Wifi to turn on. In [MENTION=3443260]hga89[/MENTION]'s case, WiFi was working, and then overnight, it stopped working. Restoring the stock firmware didn't help at all. He managed to get some logs:

I installed CM 13 from August 21 on the tablet, used SysLog to save the various boot files and then searched for lines containing "wifi". I did find a couple of lines of interest.

In DMESG.LOG, around line 1838 forward:
[ 5.754582] pci_unregister_driver: Enter
[ 5.754645] [c5] dhd_wifi_platform_load_pcie: pcie_register_driver failed
[ 5.754793] [c5] unregister wifi platform drivers
[ 5.754804] [c5] dhd_module_init: Failed to load the driver, try cnt 3
[ 5.754988] [c5] dhdpcie_bus_register: dhdpcie initialize failed.
[ 5.754999] [c5]
[ 5.754999]
[ 5.754999] pci_unregister_driver: Enter
[ 5.755052] [c5] dhd_wifi_platform_load_pcie: pcie_register_driver failed
[ 5.755165] [c5] unregister wifi platform drivers
[ 5.755177] [c5] dhd_module_init: Failed to load the driver, try cnt 2
[ 5.755401] [c5] dhdpcie_bus_register: dhdpcie initialize failed.
[ 5.755410] [c5]
[ 5.755410]
[ 5.755410] pci_unregister_driver: Enter
[ 5.755448] [c5] dhd_wifi_platform_load_pcie: pcie_register_driver failed
[ 5.755565] [c5] unregister wifi platform drivers
[ 5.755577] [c5] dhd_module_init: Failed to load the driver, try cnt 1
[ 5.755740] [c5] dhdpcie_bus_register: dhdpcie initialize failed.
[ 5.755750] [c5]
[ 5.755750]
[ 5.755750] pci_unregister_driver: Enter
[ 5.755797] [c5] dhd_wifi_platform_load_pcie: pcie_register_driver failed
[ 5.755919] [c5] unregister wifi platform drivers
[ 5.755936] [c5] dhd_module_init: Failed to load the driver, try cnt 0
[ 5.755975] [c5] dhd_module_init: Failed to load driver max retry reached**
[ 5.755985] [c5] dhd_module_init out
[ 5.757355] [c5] Freeing unused kernel memory: 1036K (c0d00000 - c0e03000)
[ 5.758053] [c4] init: Service 'wifiloader' (pid 2570) exited with status 0

in LOGCAT.LOG on line 348:
08-24 09:33:35.733 W/PackageParser( 2903): Ignoring duplicate uses-permissions/uses-permissions-sdk-m: android.permission.ACCESS_WIFI_STATE in package: com.android.phone at: Binary XML file line #132

Further down:
08-24 09:33:37.054 D/WifiController( 2903): isAirplaneModeOn = false, isWifiEnabled = false, isScanningAvailable = false
08-24 09:33:37.055 I/WifiService( 2903): Registering wifi
08-24 09:33:37.056 I/SystemServiceManager( 2903): Starting com.android.server.wifi.WifiScanningService
08-24 09:33:37.056 I/WifiScanningService( 2903): Creating wifiscanner
08-24 09:33:37.056 I/WifiScanningService( 2903): Starting wifiscanner
08-24 09:33:37.057 I/SystemServiceManager( 2903): Starting com.android.server.wifi.RttService

And even further down:
08-24 09:33:37.251 D/WifiApConfigStore( 2903): 2G band allowed channels are:1,6,11

Going further down:
08-24 09:33:38.342 D/BluetoothManagerService( 2903): Bluetooth boot completed
08-24 09:33:38.343 I/WifiService( 2903): WifiService starting up with Wi-Fi disabled
08-24 09:33:38.347 I/WifiScanningService( 2903): Registering wifiscanner

And finally:
08-24 09:33:43.750 D/ConnectivityService( 2903): Got NetworkFactory Messenger for WIFI
08-24 09:33:43.750 D/ConnectivityService( 2903): Got NetworkFactory Messenger for WIFI_UT
08-24 09:33:43.750 D/WIFI ( 2903): got request NetworkRequest [ id=1, legacyType=-1, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VPN] ] with score 0
08-24 09:33:43.750 D/WIFI_UT ( 2903): got request NetworkRequest [ id=1, legacyType=-1, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VPN] ] with score 0

Not sure I am reading the above but it suggests that a driver is missing and possibly some permission mismatch. If correct, perhaps the other messages derive from those?

What do you think?
08-24 09:33:38.349 I/RttService( 2903): Registering rttmanager

[MENTION=4899305]ashyx[/MENTION] seemed to think that a hardware failure was possible, but he wasn't quite sure.

By the way, this is from a T810.

THIS ALSO EXPLAINS WHY some people had working WiFi on the CM12.1/CM13 threads and some didn't. (Also the camera...?)

Possible Causes:

Hardware Failure:

Seems likely. This is all off of memory, but according to [MENTION=4899305]ashyx[/MENTION], the wifi driver uses "pcie_register_driver" to do 2 things:

- Initialize the PCIe device (in this case, the WiFi card)

- Initialize the driver (in this case, the WiFi driver)

According to him, the issue is in initializing the PCIe device, which is failing. This could explain the seemingly random issues people are having.

Another cause:

Different hardware revisions

This one actually seems somewhat likely to me. So, what if Samsung, halfway through production, decided to change their WiFi card model? So, people come from their working stock firmware designed for that hwrev, to a custom ROM, which doesn't work with that wifi device, back to the stock firmware, which could have been pulled from a device with a different hwrev. In theory, this would explain 2 things:

- People having WiFi break on a ROM, and restoring to stock doesn't fix the problem

- In the CM thread, I saw some people having a non-working camera/wifi, and some had a working camera/wifi. If the ROM was compiled for one hwrev, this would explain why.

THREADS OF INTEREST

My Lightning ROM thread - this thread is littered with people having broken Wifi, and people with working wifi.

TWRP thread - same story as above.

eMMC backup request thread - This is [MENTION=3443260]hga89[/MENTION]'s case.

Possibly related thread?

http://xdaforums.com/tab-s2/help/t813-wifi-flash-t3436494 - broken wifi thread

Possible hardware differences?

Wifi dropping randomly

And MANY more that I don't have time to include. Link any more interesting threads.

So, what do you think?

Am I just being crazy here, or is something seriously wrong here?

Please - dump all WiFi issue info here, including logs. I want to get as many logs as I can from different models. You can use Syslog to extract them.