From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752685Ab2H1XBy (ORCPT ); Tue, 28 Aug 2012 19:01:54 -0400 Received: from mms1.broadcom.com ([216.31.210.17]:2545 "EHLO mms1.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751324Ab2H1XBv (ORCPT ); Tue, 28 Aug 2012 19:01:51 -0400 X-Server-Uuid: 06151B78-6688-425E-9DE2-57CB27892261 Message-ID: <503D4DD9.2060808@broadcom.com> Date: Tue, 28 Aug 2012 16:01:45 -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> In-Reply-To: <503D48AC.5040509@wwwdotorg.org> X-WSS-ID: 7C23922B3MK25567099-01-01 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 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. Regards, Franky