On Tue, 11 Oct 2011, Markus Rechberger wrote: > Hi Greg, Alan, > > so I just received another device, the device supports Bulk transfers > only and only returns jerky data with Linux. > Unfortunately I guess it's based on the chipset since the datatransfer > needs the lowest common multiple buffersize. > The datapackets which I need are 188 bytes big, the EP size is 512 > bytes, the buffer needed in order to get working data > is 24064 bytes which exceeds the current accepted buffersize in Linux. > I'm having exactly the same problem with MacOSX with lower > packetsizes, but OSX allows bigger packet sizes so it's easy to fix. > It's the same with Windows. > > Now is there any way to improve this situation? > Additional to the video service, the device itself uses software > demodulation for digital radio and has several vendor specific parts > in userspace. Instead of using a single 24064-byte transfer, you can try submitting a first transfer of 12288 bytes followed by a second transfer of 11776 bytes. This will mean the sixty-sixth 188-byte datapacket will be split between the two transfers, but that shouldn't cause any difficulty. (The numbers 12288 and 11776 are the two multiples of 512 closest to 12032 = 24064 / 2.) Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
