On Tue, Jul 21, 2009 at 11:47 PM, Steve Castellotti<sc@xxxxxxxxxxxxx> wrote: > On 07/21/2009 07:32 PM, Devin Heitmueller wrote: >> >> I agree that *in theory* you should be able to do two devices. A back >> of the envelope calculation of 640x480 at 30fps in YUVY capture should >> be about 148Mbps. That said, I don't think the scenario you are >> describing has really been tested/debugged previously. If I had to >> guess, my suspicion would be a bug in the driver code that calculates >> which USB alternate mode to operate in, which results in the driver >> reserving more bandwidth than necessary. >> >> I would have dig into the code and do some testing in order to have a >> better idea where the problem is. Do you have a specific em28xx >> product in mind that you intend to use? >> > > Well in theory there's no difference between theory and practice, but in > practice there is (c: > > > More than happy to coordinate some testing of a variety of em28xx devices > we have handy around the office if it would help isolate any bugs. We could > throw some QA resource at the problem if nothing else. > > > One of the devices we're supposed to be able to acquire in bulk is > no-name brand that simply says "VC-211A" on the label. "lsusb" output looks > like this: > > ID eb1a:2861 eMPIA Technology, Inc. > > > The other says "GrabBeeX+ deluxe" and has this identifier: > > > ID eb1a:2821 eMPIA Technology, Inc. > > > We have a 2-3 others on hand as well. > > > Once again, thanks for the responsiveness and please let me know what we > can do to contribute. Well, I think I own something like nine different em28xx products, so I should be able to hook a couple of them up at the same time and debug the issue. The only issue at this point is that I already have a rather full plate of issues I am currently working. I'll see if I can schedule some cycles in the next couple of weeks to take a look (unless someone else wants to step up and debug the issue). Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
