Realistic bandwidth to get through ehci controller on a dm3730?

Realistic bandwidth to get through ehci controller on a dm3730?

[Jonathan Cameron]

Hi All,

Just wondering if anyone had any figures for how much data one can expect
the omap3's usb controller to handle?

I'm trying to get a playstation eye (ov534) camera to run as at 60fps,
but gspca is giving me payload errors at 50fps or 60fps. (50*640*480 bytes
per sec, or about 122Mbits / sec (15MB / sec)

Quick and dirty tests of the beagle xm's network adapter suggest about
4MB/s so even at 40 fps when the camera is fine, I'm way above that.

Anyhow. Basically I'm trying to work out if I've run into a brick wall
or if it is worth more time to get this to work?

Thanks,

Jonathan
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Re: Realistic bandwidth to get through ehci controller on a dm3730?

[Ming Lei]

Hi,

On Thu, Jul 14, 2011 at 11:14 PM, Jonathan Cameron <jic23-KWPb1pKIrIJaa/9Udqfwiw@public.gmane.org> wrote:
> Hi All,
>
> Just wondering if anyone had any figures for how much data one can expect
> the omap3's usb controller to handle?
>
> I'm trying to get a playstation eye (ov534) camera to run as at 60fps,
> but gspca is giving me payload errors at 50fps or 60fps. (50*640*480 bytes
> per sec, or about 122Mbits / sec (15MB / sec)

As far as I know, uvc can work well at 3*1024B/uF(24MB/s) in beagle xm, and
it uses ISO transfer.

I don't know if gspca uses ISO endpoint to transfer stream data. If it uses bulk
to transfer video data, it will share the usb bandwidth with other devices.

thanks,
-- 
Ming Lei
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