On Thu, Oct 20, 2011 at 12:05 PM, Felipe Balbi <balbi@xxxxxx> wrote: > Hi, > > On Thu, Oct 20, 2011 at 11:52:27AM +0200, Javier Martinez Canillas wrote: >> > 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 :-( >> >> I forgot to tell you more about our environment. We are using an Arago >> project v2.6.37 kernel for OMAP3 devices. > > Then, I'm sorry, but you need to seek support with Arago, or your TI > representative, for that matter. Community can't help. > Yes, shouldn't ask here. I'm sorry. I just asked because I thought it could be a common problem for both TI's kernel and upstream. But you are right I'll seek support with the Arago people. Thanks a lot for your help and answers, -- Javier Martínez Canillas (+34) 682 39 81 69 Barcelona, Spain -- 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
