Hi Larry, I have not hear back from you since that I provided the information that you asked me. Did you find something? I did some investigation on my side and I think that I have narrow down quite a bit the cause of my problem unless I receive some assistance, I am not sure that I can advance very much further by myself. Is this usual for a Wifi device to spend about 340 ms in a irq handler??? First, something that I have noticed in net/wireless/rtlwifi/core.c, function rtl_op_config(), there is a call to mdelay(50). I'm pretty much certain that this delay could be safely replaced with msleep(50). It should be ok since the function can already sleep by calling mutex_lock(). Do you agree? Here is the sequence of events that I have traced that seem to cause my audio playback underrun. 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 enable interrupts on the device 6. as soon as local irqs are reenabled before exiting rtl_ips_nic_on, a RX interrupt is handled and _rtl_pci_interrupt appears to be taking about 340 ms to process the interrupt. I have measured that time by placing 2 printks between spin_unlock_irqrestore(&rtlpriv->locks.ips_lock, flags); in rtl_ips_nic_on(). [ 69.376012] rtlwifi:rtl_ips_nic_on():<0-1> before spin_unlock_irqrestore [ 69.711920] rtl_pci:_rtl_pci_interrupt():<10000-1> Rx ok interrupt! [ 69.711948] rtlwifi:rtl_ips_nic_on():<0-0> after spin_unlock_irqrestore Also from an exchange that I had with Takashi [1], if my audio buffer size is 371 msec, the playback is smooth. If it is set to 341 msec, I have underruns. notice the proximity of values between the time it takes for rtl8192ce to service its irq and the audio buffer size causing troubles. I think that it would be very surprising if it is just a coincidence.... [1] http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071569.html On Wed, 2014-01-15 at 11:01 -0600, Larry Finger wrote: > On 01/15/2014 12:37 AM, Olivier Langlois wrote: > > How to reproduce: > > > > 1. Enable Wifi while not connecting to any AP. > > 2. lano1106@hpmini ~/Music $ aplay -c1 sine.wav > > underrun!!! (at least 1856093977.967 ms long) > > Olivier, > > I am certain that rtl8192ce does not disable interrupts for 2 sec, but I need > some more info from you. > > What is your CPU situation? I suspect x86_64, but please confirm. How many CPUs? > What is the maximum CPU speed? > > What distro? > > How do you control the wifi? Is it NetworkManager? This is important because the > device driver does not initiate any scans on its own - scans are initiated and > controlled by upstream. > > Please provide a URL for the test file sine.wav. If it is part of your distro, > then put it in a public repository, or E-mail it to me privately. > > Larry > > > -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
