[linux-dvb] Multiple em28xx devices

Douglas Schilling Landgraf dougsland at gmail.com
Thu Apr 9 16:14:42 CEST 2009


Hello rvf16,

On Thu, 09 Apr 2009 17:05:36 +0300
rvf16 <rvf16 at yahoo.gr> wrote:

> Hello.
> 
> I am trying to use two Terratec Cinergy Hybrid T USB XS FM tuners, at 
> the same time, on the same system.
> Both work great when used solely.
> When used simultaneously the second one gives the following error :
> 
> v4l2: unable to open '/dev/video1': No space left on device
> 
> I am using the em28xx-new-b2e841c05e94 driver from 
> http://mcentral.de/hg/~mrec/em28xx-new on a Fedora 6 system.
> I have opened this topic in the em28xx mailing list 
> http://mcentral.de/pipermail/em28xx/ but it seems it is not
> maintained any more.
> 
> According to comments on relevant problems (the following is for
> spca5xx driver for cameras with same problem) :
> -----------------------
> When other USB devices are present on the same host controller bus as 
> the camera, the bandwidth requirements of the spca5xx driver are not 
> being met, with some hardware configurations.
> The spca5xx driver is asking for more bandwidth than is available
> which results in these error messages.
> -----------------------
> 
> We are, under these circumstances, advised to either insert the
> device in another USB socket or even install a PCI card with extra
> USB sockets so that the device ends up in different bus.
> I tried to insert the second device in another usb socket but it
> always ends up at the same bus with the first one :
> 
> #lsusb
> Bus 005 Device 014: ID 0ccd:0072 TerraTec Electronic GmbH
> Bus 005 Device 015: ID 0ccd:0072 TerraTec Electronic GmbH
> Bus 005 Device 001: ID 0000:0000 Bus 002 Device 006: ID 046d:c50e 
> Logitech, Inc. MX-1000 Cordless Mouse Receiver
> Bus 002 Device 001: ID 0000:0000 Bus 004 Device 001: ID 0000:0000 Bus 
> 003 Device 001: ID 0000:0000 Bus 001 Device 001: ID 0000:0000
> which happens to a lot of people from what i have seen.
> 
> As this is a laptop with 4 USB sockets :
> 
> # lspci | grep USB
> 00:1d.0 USB Controller: Intel Corporation 82801G (ICH7 Family) USB
> UHCI #1 (rev 01)
> 00:1d.1 USB Controller: Intel Corporation 82801G (ICH7 Family) USB
> UHCI #2 (rev 01)
> 00:1d.2 USB Controller: Intel Corporation 82801G (ICH7 Family) USB
> UHCI #3 (rev 01)
> 00:1d.3 USB Controller: Intel Corporation 82801G (ICH7 Family) USB
> UHCI #4 (rev 01)
> 00:1d.7 USB Controller: Intel Corporation 82801G (ICH7 Family) USB2
> EHCI Controller (rev 01)
> 
> i cannot install a PCI card with extra USB sockets so there goes 
> workaround number two.
> 
> In spca5xx case a developer patched the driver so that the bandwidth
> was throttled in such a way that two devices used simultaneously
> would never exceed maximum.
> 
> Can that be done with em28xx?
> If not, is there any other workaround to this problem?

Please use upstream repository, we do not support sources from
http://mcentral.de/hg/~mrec/em28xx-new this is a parallel project.

For additional info how to download upstream tree see:
http://www.linuxtv.org/wiki/index.php/How_to_Obtain%2C_Build_and_Install_V4L-DVB_Device_Drivers

Cheers,
Douglas



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