Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752483Ab2H1XKV (ORCPT ); Tue, 28 Aug 2012 19:10:21 -0400 Received: from mms3.broadcom.com ([216.31.210.19]:2086 "EHLO mms3.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751021Ab2H1XKT (ORCPT ); Tue, 28 Aug 2012 19:10:19 -0400 X-Server-Uuid: B86B6450-0931-4310-942E-F00ED04CA7AF Message-ID: <503D4FCF.7030109@broadcom.com> Date: Tue, 28 Aug 2012 16:10:07 -0700 From: "Franky Lin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120714 Thunderbird/14.0 MIME-Version: 1.0 To: "Stephen Warren" 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> <503D4E7F.9010205@wwwdotorg.org> In-Reply-To: <503D4E7F.9010205@wwwdotorg.org> X-WSS-ID: 7C2390D349824568259-01-01 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3110 Lines: 75 On 08/28/2012 04:04 PM, Stephen Warren wrote: > 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. > Will keep you posted. Franky -- 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/