Hi, 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. -- balbi -- 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
