Date:	Thu, 30 Jan 2014 14:19:50 -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, mlang45@...ytele.com
Subject: Re: [PATCH] rtl8192ce is disabling the irqs for too long

On 01/30/2014 12:22 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 interrupts on the device
>
> 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>
> ---
>   drivers/net/wireless/rtlwifi/ps.c           |  2 +-
>   drivers/net/wireless/rtlwifi/rtl8192ce/hw.c | 18 ++++++++++++++++--
>   2 files changed, 17 insertions(+), 3 deletions(-)

Olivier,

I like the fact that you have proposed a solution that has minimal effect on the 
other PCI drivers under rtlwifi. That certainly decreases the amount of testing 
needed. Of course, all of them may need the same kind of fix.

The changes are certainly minimal; however, I do need to test them before giving 
my Ack.

As the problem(s) fixed by this patch will affect stable kernels, you should add 
a "Cc: Stable <stable@...r.kernel.org>" patch.

Originally, I was going to have you add a comment to the commit message on why 
you were changing the return value in rtl_ps_enable_nic(), but now I am thinking 
that this should be a separate commit as it fixes a totally different bug. Yes 
it is involved with the callback to hw_init, but the bug is independent.

Good work on finding this problem.

Larry

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