From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761538Ab0J2QfY (ORCPT ); Fri, 29 Oct 2010 12:35:24 -0400 Received: from www.tglx.de ([62.245.132.106]:45618 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751729Ab0J2QfW (ORCPT ); Fri, 29 Oct 2010 12:35:22 -0400 Date: Fri, 29 Oct 2010 18:34:25 +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: MULTIPART/MIXED; BOUNDARY="-1463795968-95874718-1288370067=:2692" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463795968-95874718-1288370067=:2692 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT On Fri, 29 Oct 2010, Rabin Vincent wrote: > On Fri, Oct 29, 2010 at 8:56 PM, Thomas Gleixner wrote: > > 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 ? > > Note that I haven't actually seen the multiple devices to expander GPIO > (yet?, though I've seen the multiple devices to onchip GPIO). It seemed > to be something missing from the irq handling though, rather than > something that was left out on purpose. No, I left it out on purpose and I'd rather go w/o it unless there is a intree user. Thanks, tglx ---1463795968-95874718-1288370067=:2692--