Hi, I have been discussing this problem over the alsa-devel mailing list and Daniel Mack asked me if I could repost my finding over here. If I use ALSA for playback while my wifi card is on but not connected to any AP (it is possibly scanning the air to find APs), I experience what ALSA calls underruns at regular interval (about every 1-2 seconds). underruns makes audible short click sounds. If I connect to a Wifi network or close the Wifi, the crackles and clicks go away. my explanation of the behavior is that in that specific state, the rtl8192ce driver is disabling interrupts for too long and stop my sound device irqs to be timely serviced. I am currently using kernel 3.12.7 but I had this small problem as far as I remember. At least since 3.7. This is important as I have noticed that rtl8192ce did change in 3.12.7 Here is the HW in question: 00:1b.0 Audio device [0403]: Intel Corporation NM10/ICH7 Family High Definition Audio Controller [8086:27d8] (rev 02) Subsystem: Hewlett-Packard Company Device [103c:1584] Flags: bus master, fast devsel, latency 0, IRQ 45 Memory at 96200000 (64-bit, non-prefetchable) [size=16K] Capabilities: [50] Power Management version 2 Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+ Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00 Capabilities: [100] Virtual Channel Capabilities: [130] Root Complex Link Kernel driver in use: snd_hda_intel Kernel modules: snd_hda_intel 01:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8188CE 802.11b/g/n WiFi Adapter [10ec:8176] (rev 01) Subsystem: Hewlett-Packard Company Device [103c:1629] Flags: bus master, fast devsel, latency 0, IRQ 16 I/O ports at 3000 [size=256] Memory at 95000000 (64-bit, non-prefetchable) [size=16K] Capabilities: [40] Power Management version 3 Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+ Capabilities: [70] Express Endpoint, MSI 00 Capabilities: [100] Advanced Error Reporting Capabilities: [140] Virtual Channel Capabilities: [160] Device Serial Number 01-91-81-fe-ff-4c-e0-00 Kernel driver in use: rtl8192ce Kernel modules: rtl8192ce 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) -- 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
