From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com ([192.55.52.115]:58302 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1163853AbcKAMVd (ORCPT ); Tue, 1 Nov 2016 08:21:33 -0400 Date: Tue, 1 Nov 2016 14:21:14 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Felipe Balbi Cc: Linux USB , David Miller , stable@vger.kernel.org Subject: Re: [PATCH] usb: gadget: u_ether: remove interrupt throttling Message-ID: <20161101122114.GR4617@intel.com> References: <20161101112959.19640-1-felipe.balbi@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20161101112959.19640-1-felipe.balbi@linux.intel.com> Sender: stable-owner@vger.kernel.org List-ID: On Tue, Nov 01, 2016 at 01:29:59PM +0200, Felipe Balbi wrote: > According to Dave Miller "the networking stack has a > hard requirement that all SKBs which are transmitted > must have their completion signalled in a fininte > amount of time. This is because, until the SKB is > freed by the driver, it holds onto socket, > netfilter, and other subsystem resources." > > In summary, this means that using TX IRQ throttling > for the networking gadgets is, at least, complex and > we should avoid it for the time being. > > Cc: > Reported-by: Ville Syrj�l� > Suggested-by: David Miller > Signed-off-by: Felipe Balbi Fixes laggy/hangy g_ether on my BYT FFRD8 tablet, caused by commit 55a0237f8f47 ("usb: dwc3: gadget: use allocated/queued reqs for LST bit") Tested-by: Ville Syrj�l� > --- > drivers/usb/gadget/function/u_ether.c | 8 -------- > 1 file changed, 8 deletions(-) > > diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c > index f4a640216913..119a2e5848e8 100644 > --- a/drivers/usb/gadget/function/u_ether.c > +++ b/drivers/usb/gadget/function/u_ether.c > @@ -589,14 +589,6 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb, > > req->length = length; > > - /* throttle high/super speed IRQ rate back slightly */ > - if (gadget_is_dualspeed(dev->gadget)) > - req->no_interrupt = (((dev->gadget->speed == USB_SPEED_HIGH || > - dev->gadget->speed == USB_SPEED_SUPER)) && > - !list_empty(&dev->tx_reqs)) > - ? ((atomic_read(&dev->tx_qlen) % dev->qmult) != 0) > - : 0; > - > retval = usb_ep_queue(in, req, GFP_ATOMIC); > switch (retval) { > default: > -- > 2.10.1 -- Ville Syrj�l� Intel OTC