rtlwifi: rtl8192ce: Fix too long disable of IRQs

rtlwifi: rtl8192ce: Fix too long disable of IRQs

commit f78bccd79ba3cd9d9664981b501d57bdb81ab8a4 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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>