commit f78bccd7 upstream.

rtl8192ce is disabling for too long the local interrupts during hw initiatialisation when performing scans

The observable symptoms in dmesg can be:

- underruns from ALSA playback
- clock freezes (tstamps do not change for several dmesg entries until irqs are finaly reenabled):

[  250.817669] rtlwifi:rtl_op_config():<0-0-0> 0x100
[  250.817685] rtl8192ce:_rtl92ce_phy_set_rf_power_state():<0-1-0> IPS Set eRf nic enable
[  250.817732] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.817796] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.817910] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818024] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818139] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818253] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818367] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818472] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818472] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818472] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818472] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:18051d59:11
[  250.818472] rtl8192ce:_rtl92ce_init_mac():<0-1-0> reg0xec:98053f15:10
[  250.818472] rtl8192ce:rtl92ce_sw_led_on():<0-1-0> LedAddr:4E ledpin=1
[  250.818472] rtl8192c_common:rtl92c_download_fw():<0-1-0> Firmware Version(49), Signature(0x88c1),Size(32)
[  250.818472] rtl8192ce:rtl92ce_enable_hw_security_config():<0-1-0> PairwiseEncAlgorithm = 0 GroupEncAlgorithm = 0
[  250.818472] rtl8192ce:rtl92ce_enable_hw_security_config():<0-1-0> The SECR-value cc
[  250.818472] rtl8192c_common:rtl92c_dm_check_txpower_tracking_thermal_meter():<0-1-0> Schedule TxPowerTracking direct call!!
[  250.818472] rtl8192c_common:rtl92c_dm_txpower_tracking_callback_thermalmeter():<0-1-0> rtl92c_dm_txpower_tracking_callback_thermalmeter
[  250.818472] rtl8192c_common:rtl92c_dm_txpower_tracking_callback_thermalmeter():<0-1-0> Readback Thermal Meter = 0xe pre thermal meter 0xf eeprom_thermalmeter 0xf
[  250.818472] rtl8192c_common:rtl92c_dm_txpower_tracking_callback_thermalmeter():<0-1-0> Initial pathA ele_d reg0xc80 = 0x40000000, ofdm_index=0xc
[  250.818472] rtl8192c_common:rtl92c_dm_txpower_tracking_callback_thermalmeter():<0-1-0> Initial reg0xa24 = 0x90e1317, cck_index=0xc, ch14 0
[  250.818472] rtl8192c_common:rtl92c_dm_txpower_tracking_callback_thermalmeter():<0-1-0> Readback Thermal Meter = 0xe pre thermal meter 0xf eeprom_thermalmeter 0xf delta 0x1 delta_lck 0x0 delta_iqk 0x0
[  250.818472] rtl8192c_common:rtl92c_dm_txpower_tracking_callback_thermalmeter():<0-1-0> <===
[  250.818472] rtl8192c_common:rtl92c_dm_initialize_txpower_tracking_thermalmeter():<0-1-0> pMgntInfo->txpower_tracking = 1
[  250.818472] rtl8192ce:rtl92ce_led_control():<0-1-0> ledaction 3
[  250.818472] rtl8192ce:rtl92ce_sw_led_on():<0-1-0> LedAddr:4E ledpin=1
[  250.818472] rtlwifi:rtl_ips_nic_on():<0-1-0> before spin_unlock_irqrestore
[  251.154656] PCM: Lost interrupts? [Q]-0 (stream=0, delta=15903, new_hw_ptr=293408, old_hw_ptr=277505)

The exact code flow that causes that is:

1. wpa_supplicant send a start_scan request to the nl80211 driver
2. mac80211 module call rtl_op_config with IEEE80211_CONF_CHANGE_IDLE
3.   rtl_ips_nic_on is called which disable local irqs
4.     rtl92c_phy_set_rf_power_state() is called
5.       rtl_ps_enable_nic() is called and hw_init()is executed and then the interrupts on the device are enabled

A good solution could be to refactor the code to avoid calling rtl92ce_hw_init() with the irqs disabled
but a quick and dirty solution that has proven to work is
to reenable the irqs during the function rtl92ce_hw_init().

I think that it is safe doing so since the device interrupt will only be enabled after the init function succeed.
Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>