Laptop webcam recognized but not working

[z1326]

My laptop: Dell Alienware M17X R4

Specs:HM77 chipset, i7-3610qm(HD4000 ticked), 12GB ram, AMD 7970M graphics(Blocked in dsdt to save power and reduce heat produce),Crucial C400 256G SSD, 1TB HDD, 1920x1080 WLED display

 

I installed Yosemite on my laptop and modified my dsdt.Thanks to Rehabman`s patches I`ve overcomed most of the difficulties. (eg,HD4000,battery icon,backlight,dsdt errors) But the webcam remained malfunction.

 

 

As you  can see the webcam in the USB info of system report is allright.
(Translation：集线器-Hub，产品ID-Product ID，厂商ID-Vendor ID，版本-Version，速度-Speed，制造商-Manufacturer,位置ID-Location ID,BCM20702A0-The bluetooth chip)

 

 

But if I go to the page of camera in system report,`no video captrue device founded` will be replied after a long time of spinning wheel.(As is shown in the pictrue )
(Translaton：相机-Camera，找不到视频采集设备-no video captrue device founded)

 

Also

FaceTime-Stucked when opened,need force teminate
PhotoBooth-No camera founded.
 
Now I`m convinced that this is not the hardware`s fault since the same laptop webcam is reported normally fuctional by others.
For example,here  
http://www.insanelym...adeon-7970m-hd/
(I tried this dsdt and there is no luck)
 
And I have a friend who use the same laptop.He also installed Yosemite on it.His webcam is OK,too.I also tried his dsdt and kext drivers,I  flashed the same BIOS as his,I even ask him to have his OS X partition packed to a image and I restored the image but the problem remained.
 
And I find that after the webcam failed in OSX,when I reboot to Windows,Windows will report that there is an unknown device which can`t be recognized (In fact the unknown device is the webcam). The only way to get the webcam back is pressing `fn+f9` twice to turn the webcam off and on again.
 
The only difference of the hardware I can find between mine laptop and my friend`s laptop is the wireless config.The Alienware M17X R4 has two kinds of wireless config.The first one is intel 2230 wifi-bluetooth combination card(My friend`s laptop) and the second is Killer N1103 wificard+Broadcom BCM20702A bluetooth chip(my laptop,and I`ve replaced the Killer N1103 to BCM4322(Dell DW1510) since it can`t be ticked under OS X .I also flashed the BCM4322`s ID to make it a `pure` apple device under Linux ) 
 
The difference is: for the intel 2230 combination card config,the bluetooth and the webcam don`t share the same internal USB hub but for my config the BCM20702A0 share the same internal USB hub with the webcam.However I  disabled the bluetooth in BIOS to test but the webcam is still half dead as discribed above.
 
I also found the following things in the system log which I believe it`s the webcam.
 
AppleUSBEHCI：Found  a transaction which hasn't moved in 5000 milliseconds on bus 0x1a,time out! (Addr:4,EP:0)
apsd Certificate not yet generated
 
I`ve search the Internet for almost a month and till now there`s no clue.However these two unlucky guys seemed to experience the same problem as me.

 

http://www.tonymacx86.com/yosemite-laptop-support/147227-hp-pavilion-dv6-6121tx-2nd-gen-camera-not-working.html

 

http://www.tonymacx8...ot-working.html
 
So now I`m wondering if there`s something wrong with the internal USB port.So please help me to diagnose the problem.
 
BTW:Is there someone who have the USBProber.app ?I think it`s apple`s USB transprot sniffing program.It should be in the IOUSBFamily.kext-Plugin but I can`t find it there and since I don`t have a developer account I can`t download that from apple website.

 

And here`s my ioreg.Alienware-M17X-R4-MacBook Pro.zip

 

(If there`re some gramma or spelling mistakes then I`m soory for my poor English   )

[z1326]

getdump.rtf

Here is the getdump of the audio card。

[z1326]

getdump v2.8.7.rtf

[z1326]

codec_dump.txt

 

codec extracted from Ubuntu

[teddybearapple]

My camera only works after a fresh installation. And then after installing kexts it doesn't Recognise anymore. I saved my ioreg it after a fresh installation and can see my camera in it . Can someone use my ioreg and do some DSTD patching to recognize my camera?