From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:32937 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751439AbcKCAXF (ORCPT ); Wed, 2 Nov 2016 20:23:05 -0400 Date: Thu, 3 Nov 2016 08:23:01 +0800 From: Peter Chen To: David Miller Cc: felipe.balbi@linux.intel.com, linux-usb@vger.kernel.org, ville.syrjala@linux.intel.com, stable@vger.kernel.org Subject: Re: [PATCH] usb: gadget: u_ether: remove interrupt throttling Message-ID: <20161103002300.GA894@b29397-desktop> References: <20161101112959.19640-1-felipe.balbi@linux.intel.com> <20161102060202.GD28525@b29397-desktop> <20161102.112254.1243059410485662386.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161102.112254.1243059410485662386.davem@davemloft.net> Sender: stable-owner@vger.kernel.org List-ID: On Wed, Nov 02, 2016 at 11:22:54AM -0400, David Miller wrote: > From: Peter Chen > 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. 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. -- Best Regards, Peter Chen