Hi, On Thu, Oct 20, 2011 at 10:19:41AM +0200, Javier Martinez Canillas wrote: > Sorry if this is not the right place to ask this. But I didn't find an > USB user mailing list. > > We have a custom TI DM3730 board using a Mentor Graphics's USB > controller (musb_hdrc). We are using the usb ethernet gadget (g_ether) > to create a point-to-point ethernet network between the board and a > host PC. > > The problem is that even when the bus is USB 2.0 with a theoretical > transfer rate of 480 Mbps, we are only getting about 55 Mbps from the > host to the target and about 65 Mbps from the target to the host. > > We are pretty sure that the board can handle more traffic than that > since with a fast Ethernet 100BASE-TX connection we get about 93 Mbps. > > Is correct to get so low traffic with the usb ethernet gadget? with MUSB, yes :-s Sorry. The problem is that it has so many silicon issues that the very powerful mode1 DMA can't be used in all situations. Also, in case of ethernet packets, we will get unaligned buffers, which MUSB's internal DMA engine can't handle, then that packet has to be transferred via PIO. I don't think there's anything which could be done in this case :-( Unless anyone else has a nice tip. -- balbi
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