Intermittent: cg2900 fails to start

After enabling WiFi menu under "Settings", I realized that even if cg2900 driver fails to power-up wlan, I can restart WiFi daemon without restarting the board.

The above comment came out wrong. I meant that cg2900 driver is able to power-up wlan chip in multiple(~2) tries.

Steps to reproduce this error on Android from command line. First two steps are already a part of linaro-android boot process. So you don't need to run them explicitly.

1. Insert mac80211 and cw1200_core modules.
root@android:/ # insmod /system/modules/mac80211.ko
root@android:/ # insmod /system/modules/cw1200_core.ko

2. Run hciattach:
root@android:/ # hciattach -a 23 -n -s 115200 /dev/ttyAMA0 cg2900 115200 flow &

/*
 * Following are the "hciattach" logs, observed frequently on Android.
 */

Success:
root@android:/ # hciattach -a 23 -n -s 115200 /dev/ttyAMA0 cg2900 115200 flow &
[ 23.694732] cg2900-uart cg2900-uart.0: UART opened
[ 23.712585] cg2900-uart cg2900-uart.0: Transport connected
[ 23.725860] cg2900-uart cg2900-uart.0: Set chip power: ENABLE
Device setup complete
[ 23.989562] cg2900-uart cg2900-uart.0: Received Read Local Version Information with:
[ 23.989562] hci_version: 0x06
[ 23.989562] hci_revision: 0x0200
[ 23.989562] lmp_pal_version: 0x06
[ 23.989562] manufacturer: 0x0030
[ 23.989593] hci_sub_version: 0x0000
[ 24.014526] cg2900-uart cg2900-uart.0: Chip supported by the CG2900 chip driver
[ 24.022949] cg2900-uart cg2900-uart.0: Chip handler found
[ 24.518737] cg2900-uart cg2900-uart.0: Set chip power: DISABLE
[ 24.527343] Bluetooth: CG2900 registered
[ 24.531433] Bluetooth: Open ST-Ericsson CG2900 driver
[ 24.536560] cg2900-uart cg2900-uart.0: Set chip power: ENABLE
[ 24.540679] cg2900-audiobt cg2900-audiobt.0: CG2900 device added
[ 24.543365] cg2900-audiofm cg2900-audiofm.0: CG2900 Audio driver started
[ 24.918823] cg2900-uart cg2900-uart.0: Baud rate changed to 3000000 baud
[ 25.609161] cg2900-btacl cg2900-btacl.0: CG2900 self test failed
[ 25.673492] Bluetooth: CG2900 BT core is enabled
[ 27.809173] Bluetooth: CG2900 BT core is disabled
[ 27.813995] cg2900-uart cg2900-uart.0: Set chip power: DISABLE
[ 27.868743] cg2900-uart cg2900-uart.0: Set chip power: ENABLE
[ 28.619171] cg2900-uart cg2900-uart.0: Set chip power: DISABLE

Failure 1:
root@android:/ # hciattach -a 23 -n -s 115200 /dev/ttyAMA0 cg2900 115200 flow &
[ 408.222320] cg2900-uart cg2900-uart.0: UART opened
[ 408.231292] cg2900-uart cg2900-uart.0: Transport connected
[ 408.236877] cg2900-uart cg2900-uart.0: Set chip power: ENABLE
Device setup complete
[ 408.499389] cg2900-uart cg2900-uart.0: Received Read Local Version Information with:
[ 408.499420] hci_version: 0x06
[ 408.499450] hci_revision: 0x0200
[ 408.499450] lmp_pal_version: 0x06
[ 408.499481] manufacturer: 0x0030
[ 408.499481] hci_sub_version: 0x0000
[ 408.524444] cg2900-uart cg2900-uart.0: Chip supported by the CG2900 chip driver
[ 408.531951] cg2900-uart cg2900-uart.0: Chip handler found
[ 409.029113] cg2900-uart cg2900-uart.0: Set chip power: DISABLE
[ 409.049072] Bluetooth: CG2900 registered
[ 409.053802] Bluetooth: Open ST-Ericsson CG2900 driver
[ 409.060028] cg2900-uart cg2900-uart.0:...

We need help addressing the 3 failure scenario Amit depicted above. These occur when starting the BT stack and happen in more than 50% of the cases, rendering the wifi feature useless. We have also observed kernel crashes and dumps when the system is started with BT enabled.

The following error is reported when the BT stack encounters and error during initialization:

[ 463.513427] platform cw1200_wlan: cw1200_clk_ctrl: Failed to sys_clk_out clk enable: -5

This is normal and expected since the BT driver is smart enough to cleanup after itself upon recognizing an error condition. From there nothing works since cw1200_wlan need clock "sys_clk_out" to be instantiated.

I'm convinced we are facing more than one issue, which make the problem that much harder to characterise. It would be greatly appreciated if a connectivy kernel expert from STE could work with us to stabilize/fix the BT and wifi drivers.

Being investigated by STE connectivity people

Also observed in https://android-build.linaro.org/builds/~linaro-android/landing-snowball-12.01-release/#build=5

The new 3.3 [1] kernel is powering the chip properly now but intermittent connectivity issues still persist.

[1]. http://www.igloocommunity.org/gitweb/?p=kernel/igloo-kernel.git;a=shortlog;h=refs/heads/stable-android-ux500-3.3

I havent' seen any critical failures when the cg2900 chip is initialised with the latest stable-android-ux500-3.3 kernel. I would like to get more testing done on it before closing the bug.

If next week's testing yields satisfactory results, we should be good.
For now, I suggest we mark this bug as "Fix committed".

Thanks to all the starts for their help on this.

Not observed on:
https://android-build.linaro.org/builds/~linaro-android/snowball-ics-gcc46-igloo-stable-blob/#build=239