• Kirill Smelkov's avatar
    [media] uvcvideo: Add FIX_BANDWIDTH quirk to HP Webcam on HP Mini 5103 netbook · 949d9264
    Kirill Smelkov authored
    The camera there identifies itself as being manufactured by Cheng Uei
    Precision Industry Co., Ltd (Foxlink), and product is titled as "HP
    Webcam [2 MP Fixed]".
    
    I was trying to get 2 USB video capture devices to work simultaneously,
    and noticed that the above mentioned webcam always requires packet size
    = 3072 bytes per micro frame (~= 23.4 MB/s isoc bandwidth), which is far
    more than enough to get standard NTSC 640x480x2x30 = ~17.6 MB/s isoc
    bandwidth.
    
    As there are alt interfaces with smaller MxPS
    
        T:  Bus=01 Lev=01 Prnt=01 Port=03 Cnt=01 Dev#=  2 Spd=480  MxCh= 0
        D:  Ver= 2.00 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs=  1
        P:  Vendor=05c8 ProdID=0403 Rev= 1.06
        S:  Manufacturer=Foxlink
        S:  Product=HP Webcam [2 MP Fixed]
        S:  SerialNumber=200909240102
        C:* #Ifs= 2 Cfg#= 1 Atr=80 MxPwr=500mA
        A:  FirstIf#= 0 IfCount= 2 Cls=0e(video) Sub=03 Prot=00
        I:* If#= 0 Alt= 0 #EPs= 1 Cls=0e(video) Sub=01 Prot=00 Driver=uvcvideo
        E:  Ad=83(I) Atr=03(Int.) MxPS=  16 Ivl=4ms
        I:* If#= 1 Alt= 0 #EPs= 0 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
        I:  If#= 1 Alt= 1 #EPs= 1 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
        E:  Ad=81(I) Atr=05(Isoc) MxPS= 128 Ivl=125us
        I:  If#= 1 Alt= 2 #EPs= 1 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
        E:  Ad=81(I) Atr=05(Isoc) MxPS= 512 Ivl=125us
        I:  If#= 1 Alt= 3 #EPs= 1 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
        E:  Ad=81(I) Atr=05(Isoc) MxPS=1024 Ivl=125us
        I:  If#= 1 Alt= 4 #EPs= 1 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
        E:  Ad=81(I) Atr=05(Isoc) MxPS=1536 Ivl=125us
        I:  If#= 1 Alt= 5 #EPs= 1 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
        E:  Ad=81(I) Atr=05(Isoc) MxPS=2048 Ivl=125us
        I:  If#= 1 Alt= 6 #EPs= 1 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
        E:  Ad=81(I) Atr=05(Isoc) MxPS=2688 Ivl=125us
        I:  If#= 1 Alt= 7 #EPs= 1 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
        E:  Ad=81(I) Atr=05(Isoc) MxPS=3072 Ivl=125us
    
    UVC_QUIRK_FIX_BANDWIDTH helps here and NTSC video can be served with
    MxPS=2688 i.e. 20.5 MB/s isoc bandwidth.
    
    In terms of microframe time allocation, before the quirk NTSC video
    required 60 usecs / microframe and 53 usecs / microframe after.
    Acked-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
    Signed-off-by: default avatarKirill Smelkov <kirr@mns.spb.ru>
    Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
    949d9264
uvc_driver.c 64.1 KB