From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753568Ab2H1Wjp (ORCPT ); Tue, 28 Aug 2012 18:39:45 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:43169 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753231Ab2H1Wjn (ORCPT ); Tue, 28 Aug 2012 18:39:43 -0400 Message-ID: <503D48AC.5040509@wwwdotorg.org> Date: Tue, 28 Aug 2012 15:39:40 -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> In-Reply-To: <503CF5B3.8040201@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 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!