From: Mauro Carvalho Chehab > Sent: 30 March 2017 11:28 ... > While debugging this issue, I saw *a lot* of network-generated URB > traffic from RPi3 Ethernet port drivers that were using non-aligned > buffers and were subject to the temporary buffer conversion. Buffers from the network stack will almost always be 4n+2 aligned. Receive data being fed into the network stack really needs to be 4n=2 aligned. The USB stack almost certainly has to live with that. If the USB ethernet device doesn't have two bytes of 'pad' before the frame data (destination MAC address) then you have to solve the problem within the USB stack. For transmits it might be possible to send an initial 2 byte fragment from a separate buffer - but only if arbitrary fragment sizes are allowed. A normal USB3 controller should allow this - but you have to be very careful about what happens at the end of the ring. David -- 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
