linux_dsm_epyc7002/drivers/media/video/uvc
Kirill Smelkov 949d926458 [media] uvcvideo: Add FIX_BANDWIDTH quirk to HP Webcam on HP Mini 5103 netbook
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>
2011-07-27 17:56:05 -03:00
..
Kconfig V4L/DVB (11439): UVC: uvc_status_cleanup(): undefined reference to `input_unregister_device' 2009-04-06 21:44:52 -03:00
Makefile [media] uvcvideo: Register subdevices for each entity 2011-05-25 19:50:58 -03:00
uvc_ctrl.c [media] uvcvideo: Fix control mapping for devices with multiple chains 2011-07-27 17:56:04 -03:00
uvc_driver.c [media] uvcvideo: Add FIX_BANDWIDTH quirk to HP Webcam on HP Mini 5103 netbook 2011-07-27 17:56:05 -03:00
uvc_entity.c [media] uvcvideo: Ignore entities for terminals with no supported format 2011-06-30 23:18:13 -03:00
uvc_isight.c [media] uvcvideo: Update e-mail address and copyright notices 2010-10-21 01:18:18 -02:00
uvc_queue.c [media] uvcvideo: Remove buffers from the queues when freeing 2011-06-30 23:18:52 -03:00
uvc_status.c [media] uvcvideo: Update e-mail address and copyright notices 2010-10-21 01:18:18 -02:00
uvc_v4l2.c [media] return -ENOTTY for unsupported ioctl's at legacy drivers 2011-07-27 17:53:38 -03:00
uvc_video.c [media] uvcvideo: Disable the queue when failing to start 2011-06-30 23:19:16 -03:00
uvcvideo.h [media] uvcvideo: Use LINUX_VERSION_CODE for VIDIOC_QUERYCAP 2011-07-27 17:53:15 -03:00