04-27-2012 07:10 AM - edited 04-27-2012 01:17 PM
Procedure followed on Dell E6420:
1) Uninstalled Broadcom software (listed as WIDCOMM).
2) Rebooted the system because the uninstall requested it.
3) After reboot, Bluetooth and Microsoft Enumerator still listed in Device Manager. Uninstalled both of those via Device Manager.
4) Downloaded and ran Bluetooth installer from Broadcom site. It notified me that it could not find BT adapter and asked to plug it in or turn it on. My USB BT adapter (Rocketfish model listed in previous post) was never unplugged.
5) Left Broadcom BT software installer running. Unplugged and replugged USB BT adapter. Windows 7 found it, and it installed its own drivers for 3 out of 7 or 8 devices listed. Others were listed as "driver not found." Window disappeared so could not see what they were.
6) Broadcom software then automatically found the device and it continued its own installation. The rest of the devices "not found" above installed successfully during the Broadcom installation. All installation completed successfully.
7) Even though the software did not request it, I rebooted the system again anyway.
The BSOD yesterday happened when I paused and attempted to unpause an MP3 podcast that I was listening to via Windows Media Player v12. No BSOD's yet to report after the installation procedure above, but I will keep an eye on it.
The sporadic skipping of audio is still happening. Seems to be random. Does not appear to be related to audio level.
UPDATE: I have been moving the USB BT adapter around on the various available ports. When I connect it to one of the ports directly on the laptop, the audio skip does appear to have an interval. It usually happens about once every two seconds. Very annoying, and it happens both with streaming audio from the web and playing music from USB flash drive. However, when I connect the adapter to a port on the docking station, it is only with streaming audio. That is when the skip is sporadic, unpredictable and does not happen nearly as much.
With the BT adapter on the docking station and playing music from flash drive in a port on the laptop, the once every two second skip comes back.
With both the BT adapter and the music drive in separate ports on the docking station, the music is nearly 100% stable. Every once in a while, a skip will happen, but seems to be even less than when streaming.
The way this is going, it almost seems like this stupid Dell hardware is either polling its laptop ports every two seconds, or its own USB drivers are doing something weird. Either way, the built-in laptop ports appear to be interfering with things whenever they are used.
04-27-2012 01:17 PM - edited 04-27-2012 02:04 PM
UPDATE #2: Definitely seems to be a built-in USB hardware or driver issue. Found a DPC Latency checker program here -
Following the instructions, I disabled the USB Host Controller for the laptop built-in USB ports. The latency analyzer immediately dropped from constant yellow or red status to nearly 100% green. Every once in a while there is an audio skip yet, but they are significantly reduced now. Going to keep looking for other devices to disable to make it better.
UPDATE #3: Wow ... Google search for: Dell laptop excessive "dpc latency"
My, oh my, the results that come up. Enlightening!
04-27-2012 04:11 PM
Thank you for your detailed feedback! It is great to post as much information as you have available as it will assist other users in troubleshooting issues specific to their hardware.
04-30-2012 03:54 PM
FIXED!!! OK, more informatinon for everyone - in the order of how I proceeded!
Tried the INF update located here - http://downloadcenter.intel.com/Detail_Desc.aspx?lang=eng&DwnldID=19597
Result: No change.
Found a great information thread here - http://forum.notebookreview.com/dell-latitude-vostro-precision/341918-dell-latitude-dpc-latency-issu...
Most of the rest of the procedure I followed is based on this one.
Tried disabing the O2 SD/MMC items in Device Manager. That made a very small improvement in the DPC Latency, but not enough to make a difference with the BT audio skipping.
Focused on Intel chipset and/or driver updates first. Went here to do that - http://www.intel.com/p/en_US/support/detect?iid=dc_iduu
Graphics and WiFi drivers were out of date according to the utility at the link immediately above.
Updated Graphics, rebooted - no change in the problem.
Updated WiFi driver, rebooted - no change in the problem.
Next, focused on the Intel Rapid Storage Technology driver. Update here - http://downloadcenter.intel.com/Detail_Desc.aspx?ProductID=2101&DwnldID=20624&lang=eng&iid=dc_rss
Updated Intel RST, rebooted - no change in the problem.
Moved on to updating the BIOS of the Dell E6420 laptop. It was at the quite old A05 level.
Updated BIOS from A05 to A07, rebooted - no change in the problem.
Updated BIOS from A07 to A08, rebooted - no change in the problem.
Finally, Updated BIOS from A08 to A12, rebooted - BINGO!!! This is finally a real solution after all of the above!
All of the devices in the laptop are now enabled, and the DPC Latency has gone from constant yellow or red status, to nearly 100% green. There is an occasional yellow or red blip in the latency, and an even less occasional Bluetooth audio blip. I now attribute that to other heavy activity that I am subjecting the laptop to for my work. Also, the built-in laptop USB ports are even active now as well. When I plug in my USB flash drive, the DPC Latency does rise a bit on average, and there are a bit mroe yellow status lines. However, the BT audio is still very stable.
I hope that this information helps people encountering the issue! Enjoy!