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Subject[PATCH 3.8 20/81] rtlwifi: rtl8192ce: Fix too long disable of IRQs
Date
3.8.13.20 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Olivier Langlois <olivier@trillion01.com>

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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/net/wireless/rtlwifi/rtl8192ce/hw.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/rtlwifi/rtl8192ce/hw.c b/drivers/net/wireless/rtlwifi/rtl8192ce/hw.c
index d1f34f6..266a46e 100644
--- a/drivers/net/wireless/rtlwifi/rtl8192ce/hw.c
+++ b/drivers/net/wireless/rtlwifi/rtl8192ce/hw.c
@@ -900,14 +900,26 @@ int rtl92ce_hw_init(struct ieee80211_hw *hw)
bool is92c;
int err;
u8 tmp_u1b;
+ unsigned long flags;

rtlpci->being_init_adapter = true;
+
+ /* Since this function can take a very long time (up to 350 ms)
+ * and can be called with irqs disabled, reenable the irqs
+ * to let the other devices continue being serviced.
+ *
+ * It is safe doing so since our own interrupts will only be enabled
+ * in a subsequent step.
+ */
+ local_save_flags(flags);
+ local_irq_enable();
+
rtlpriv->intf_ops->disable_aspm(hw);
rtstatus = _rtl92ce_init_mac(hw);
if (!rtstatus) {
RT_TRACE(rtlpriv, COMP_ERR, DBG_EMERG, "Init MAC failed\n");
err = 1;
- return err;
+ goto exit;
}

err = rtl92c_download_fw(hw);
@@ -915,7 +927,7 @@ int rtl92ce_hw_init(struct ieee80211_hw *hw)
RT_TRACE(rtlpriv, COMP_ERR, DBG_WARNING,
"Failed to download FW. Init HW without FW now..\n");
err = 1;
- return err;
+ goto exit;
}

rtlhal->last_hmeboxnum = 0;
@@ -995,6 +1007,8 @@ int rtl92ce_hw_init(struct ieee80211_hw *hw)
RT_TRACE(rtlpriv, COMP_INIT, DBG_TRACE, "under 1.5V\n");
}
rtl92c_dm_init(hw);
+exit:
+ local_irq_restore(flags);
rtlpci->being_init_adapter = false;
return err;
}
--
1.8.3.2


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