On Thu, Nov 03, 2016 at 12:42:11PM +0200, Felipe Balbi wrote: > > Hi, > > Peter Chen <hzpeterchen@xxxxxxxxx> writes: > >> Peter Chen <hzpeterchen@xxxxxxxxx> writes: > >> > On Wed, Nov 02, 2016 at 11:22:54AM -0400, David Miller wrote: > >> >> From: Peter Chen <hzpeterchen@xxxxxxxxx> > >> >> Date: Wed, 2 Nov 2016 14:02:02 +0800 > >> >> > >> >> > Felipe, it may increase cpu utilization since more interrupts will be there, > >> >> > it may affect the SoC which has lower cpu frequency. This code existed > >> >> > many years, why this problem has only reported at dwc3 recently? > >> >> > >> >> It's a bug, and it's going to cause TCP sockets to potentially hang. > >> >> > >> > > >> > For some controllers, it is, so we need to add parameter for user > >> > to see if interrupt migration is supported or not. > >> > >> not for some controller, for ALL networking drivers. > >> > >> > But just like some ethernet controllers, some USB controllers support > >> > hardware timeout mechanism which interrupt will be triggered after > >> > some uFrame occurs if the transaction has completed but not required > >> > to interrupt, it is used to support interrupt migration like ethernet. > >> > >> you're missing the point. What Dave Miller is saying is that it's ALWAYS > >> a bug to delay completion of SKBs. The only thing you're doing with > >> chipidea is delaying interrupt by up to 125us; which is still a bug from > >> the point of view of the networking layer, but it's more difficult to > >> perceive any problems because of the short time where interrupt is > >> delayed. > >> > > > > If it is ALWAYS a bug to delay completion of SKBs, how the local > > ethernet driver designs interrupt migration? > > what driver are you talking about? Which "local" ethernet driver? > The ethernet driver located at drivers/net/ethernet, its device uses RJ45 connector to communicate. -- Best Regards, Peter Chen -- 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
