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Date:	Thu, 06 Feb 2014 14:38:47 -0600
From:	Larry Finger <Larry.Finger@...inger.net>
To:	Olivier Langlois <olivier@...llion01.com>, linville@...driver.com,
	chaoming_li@...lsil.com.cn
CC:	linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Stable <stable@...r.kernel.org>
Subject: Re: [PATCH 1/2] rtlwifi: rtl8192ce: Fix too long disable of IRQs

On 02/01/2014 12:11 AM, Olivier Langlois wrote:
> 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@...llion01.com>
> Cc: Stable <stable@...r.kernel.org>

Acked-by: Larry Finger <Larry.Finger@...inger.net>

Larry

> ---
>   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 a82b30a..2eb0b38 100644
> --- a/drivers/net/wireless/rtlwifi/rtl8192ce/hw.c
> +++ b/drivers/net/wireless/rtlwifi/rtl8192ce/hw.c
> @@ -937,14 +937,26 @@ 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);
> @@ -952,7 +964,7 @@ 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;
> @@ -1032,6 +1044,8 @@ 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;
>   }
>

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