From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932725Ab0J2P1X (ORCPT ); Fri, 29 Oct 2010 11:27:23 -0400 Received: from www.tglx.de ([62.245.132.106]:36722 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756541Ab0J2P1W (ORCPT ); Fri, 29 Oct 2010 11:27:22 -0400 Date: Fri, 29 Oct 2010 17:26:23 +0200 (CEST) From: Thomas Gleixner To: Rabin Vincent cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] genirq: handle shared irqs in handle_nested_irq() In-Reply-To: Message-ID: References: <1288288718-1188-1-git-send-email-rabin@rab.in> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 29 Oct 2010, Rabin Vincent wrote: > On Fri, Oct 29, 2010 at 12:24 AM, Thomas Gleixner wrote: > > On Thu, 28 Oct 2010, Rabin Vincent wrote: > >> Allow shared irqs to work when nested threads are used for handling > >> threaded interrupts. > > > > Why do we want this ? handle_nested_irq() is called from a interrupt > > demultiplexer, so why would we need shared interrupts for this ? > > Threaded IRQ + handle_nested_irq() is used by I2C GPIO expander drivers > like chained hander + generic_handle_irq() is used by on-chip GPIO > drivers. If two irq handlers are registered on an on-chip GPIO > interrupt (because two devices are externally connected), it works. If > the handlers are instead registered on one of the expander's pins' > interrupt, without this patch, only the handler registered first is > called. Have the hardware dudes not yet understood that shared interrupts are a horrible idea ? Sigh, tglx