Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752094Ab2H1XEf (ORCPT ); Tue, 28 Aug 2012 19:04:35 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:39876 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750740Ab2H1XEe (ORCPT ); Tue, 28 Aug 2012 19:04:34 -0400 Message-ID: <503D4E7F.9010205@wwwdotorg.org> Date: Tue, 28 Aug 2012 16:04:31 -0700 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120714 Thunderbird/14.0 MIME-Version: 1.0 To: Franky Lin CC: Wei Ni , Arend van Spriel , "rvossen@broadcom.com" , Rakesh Kumar , Laxman Dewangan , "linux-tegra@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-wireless@vger.kernel.org" , "brcm80211-dev-list@broadcom.com" Subject: Re: [PATCH 2/6] brcmfmac: Handling the interrupt in ISR directly for non-OOB References: <1346063114-30361-1-git-send-email-wni@nvidia.com> <1346063114-30361-3-git-send-email-wni@nvidia.com> <503B9F31.5050502@broadcom.com> <503BD345.6030501@wwwdotorg.org> <1346152413.3516.211.camel@tegra-chromium-2> <503CF5B3.8040201@broadcom.com> <503D48AC.5040509@wwwdotorg.org> <503D4DD9.2060808@broadcom.com> In-Reply-To: <503D4DD9.2060808@broadcom.com> X-Enigmail-Version: 1.5a1pre Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2963 Lines: 68 On 08/28/2012 04:01 PM, Franky Lin wrote: > On 08/28/2012 03:39 PM, Stephen Warren wrote: >> On 08/28/2012 09:45 AM, Franky Lin wrote: >>> On 08/28/2012 04:13 AM, Wei Ni wrote: >>>> On Tue, 2012-08-28 at 04:06 +0800, Stephen Warren wrote: >>>>> On 08/27/2012 09:24 AM, Arend van Spriel wrote: >>>>>> On 08/27/2012 12:25 PM, Wei Ni wrote: >>>>>>> In case of inband interrupts, if we handle the interrupt in dpc >>>>>>> thread, >>>>>>> two level of thread switching takes place to process wifi >>>>>>> interrupts. >>>>>>> One in SDHCI driver and the other in Wifi driver. This may cause the >>>>>>> system >>>>>>> instability. >> ... >>>>>> Not sure if I can follow this explanation. The isr is called with >>>>>> host >>>>>> claimed (by sdio_irq_thread) and all it does is at a linked list >>>>>> member >>>>>> and signal the dpc thread. After doing this the host is released. >>>>> >>>>> Is the issue something like the ISR handler or first level of >>>>> threading >>>>> does: >>>>> >>>>> * Trigger DPC >>>>> * Re-enable interrupt >>>>> >>>>> So that the interrupt then fires again before the triggered DPC can >>>>> run >>>>> to handle/clear it, thus causing an interrupt storm? >>>>> >>>>> Whereas handling the interrupt directly prevents this race condition? >>>> >>>> Above is my understanding. >>> >>> I understand the issue here and totally agree that we should treat >>> in-band and out-band interrupts differently. But my concern is that the >>> behavior of releasing the host before calling brcmf_sdbrcm_isr and grab >>> it after is likely error prone. Also we are restructuring the dpc >>> routine internally and it's almost done. I will find a better solution >>> for in-band interrupt and get it the queue as well. So I suggest >>> dropping this patch. >> >> Franky, do you know which kernel release the DPC restructuring will make >> it into? I ask because I can't apply the rest of the patches in this >> series without first resolving the stability issues with the Broadcom >> WiFi enabled, since that'd de-stabilize the Tegra platform >> significantly, and I'd like to plan when we can apply these patches to >> Tegra. Thanks! >> > > Hi Stephen, > > Since we submit patches through linux-wireless tree, you may only be > able to pick it up at 3.7-rc1. It's quite a big change so I don't think > it will qualify as a bug fix to get into 3.6-rcX. That's as quick as I expected it to show up, so that's great. I don't suppose you could mail Wei and myself once the patch gets into the linux-wireless tree, so we can test it out on Tegra. If the patch could possibly go into a topic branch in the wireless tree so it can be merged into the Tegra tree before this series, that would be awesome. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/