949d926458
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: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
|
||
|---|---|---|
| .. | ||
| common | ||
| dvb | ||
| radio | ||
| rc | ||
| video | ||
| Kconfig | ||
| Makefile | ||
| media-device.c | ||
| media-devnode.c | ||
| media-entity.c | ||