Re: [Spca50x-devs] GSPCA driver and serial ports
- Date: Mon, 2 Apr 2007 22:35:09 +0100
- From: "Joel Crisp" <jcrisp@xxxxxxxxxxx>
- Subject: Re: [Spca50x-devs] GSPCA driver and serial ports
Ok, looking a the manual for a CN700 based board, it does state that
the USB uses INT A,B and C on the PCI, which can be mapped to other
'traditional' interrupts. This may cause a conflict with the GPIO. You
could check the PCI IRQ steering and mapping using the 'lspci' tool
which will show you which IRQ the PCI line is mapped to.
This document also contains a lot of good information on PCI IRQ
problems : http://pcmcia-cs.sourceforge.net/ftp/doc/PCMCIA-HOWTO-4.html
It is about PCMCIA, but still relevent.
I would also think that the embedded CPU is a bit low power for full video apps.
On 4/2/07, Scott Moore <scott.moore.utd@xxxxxxxxx> wrote:
> The board is a VIA CN700 chipset with an embedded 1.5Ghz VIA CN700 NANO BGA
> processor. The serial ports are integrated into the motherboard, set to 3F8,
> IRQ 4 and 2F8, IRQ 3. In the bios they can be found under Onboard Super IO.
> Scott Moore
> On 4/2/07, Joel Crisp <jcrisp@xxxxxxxxxxx> wrote:
> > Hi
> > I'm the original author of the SPCA50x module. It was never a serial
> > port driver, it has been a USB driver all along. Where did your
> > colleague find that information?
> > Can you give me the details of your embedded board? There may be an
> > IRQ conflict, but if so it is likely to be between the USB controller
> > and the GPIO controller which will be managing the serial ports. In
> > this case, I would suggest disabling the on-board GPIO if it is a
> > desktop class machine or looking to see if you can re-configure the
> > IRQ mappings if it is embedded. Have you considered using a
> > USB->Serial bridge?
> > The SPCA50x driver doesn't hit the USB controller directly, instead it
> > sends messages to the kernel top side of the kernel driver which is
> > then responsible for calling the appropriate hardware driver to manage
> > the USB controller. This means that there is a high degree of
> > isolation of the SPCA50x driver from the USB hardware. It is similar
> > to using a socket vs. hitting the network card registers.
> > I think on balance it is more likely to be a CPU usage issue - low
> > power embedded boards can struggle with the video stream. If you are
> > doing Robotic control, you may want to snap individual frames rather
> > than a continuous stream.
> > Joel
> > On 4/2/07, Scott Moore <scott.moore.utd@xxxxxxxxx> wrote:
> > > I am a university student working on a robotics project using the gspca
> > > driver to run a Creative Webcam Live!
> > > After getting the camera working, we returned to our (previously
> > > servo controller code, which uses the serial ports on our board. We can
> > > longer send information from the serial port, though everything appears
> > > correct in stty, /dev, and /proc/interrupts. My colleague says he found
> > > post on a French website related to the camera driver where someone else
> > > a similar problem. He said that one of the developers had posted that
> > > driver had initially been written as a serial driver or some such, and
> > > therefore interfered with the serial port IRQs, or disabled them. I do
> > > know if this is the case, as I can't get the ports to work with the
> > > unloaded either. If anyone knows about the effect gspca might have on
> > > functionality, please let me know.
> > >
> > > Many thanks,
> > > Scott Moore
> > > University of Texas at Dallas
> > >
> > >
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