From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262860AbUB0Nuu (ORCPT ); Fri, 27 Feb 2004 08:50:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262867AbUB0Nut (ORCPT ); Fri, 27 Feb 2004 08:50:49 -0500 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:56587 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S262860AbUB0Nue (ORCPT ); Fri, 27 Feb 2004 08:50:34 -0500 Date: Fri, 27 Feb 2004 13:50:19 +0000 From: Russell King To: Michael Frank Cc: Benjamin Herrenschmidt , "Grover, Andrew" , Mark Gross , arjanv@redhat.com, Tim Bird , root@chaos.analogic.com, Linux Kernel list Subject: Re: Why no interrupt priorities? Message-ID: <20040227135019.A24457@flint.arm.linux.org.uk> Mail-Followup-To: Michael Frank , Benjamin Herrenschmidt , "Grover, Andrew" , Mark Gross , arjanv@redhat.com, Tim Bird , root@chaos.analogic.com, Linux Kernel list References: <1077859968.22213.163.camel@gaston> <20040227090548.A15644@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from mhf@linuxmail.org on Fri, Feb 27, 2004 at 09:31:43PM +0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 27, 2004 at 09:31:43PM +0800, Michael Frank wrote: > On Fri, 27 Feb 2004 09:05:48 +0000, Russell King wrote: > > On Fri, Feb 27, 2004 at 02:26:31PM +0800, Michael Frank wrote: > >> Is this to imply that edge triggered shared interrupts are used anywhere? > > > > It is (or used to be) rather common with serial ports. Remember that > > COM1 and COM3 were both defined to use IRQ4 and COM2 and COM4 to use > > IRQ3. > > > >> Never occured to me to use shared IRQ's edge triggered as this mode > >> _cannot_ work reliably for HW limitations. > > > > The serial driver takes great care with this - when we service such an > > interrupt, we keep going until we have scanned all the devices until > > such time that we can say "all devices are no longer signalling an > > interrupt". > > > > This is something it has always done - it's nothing new. > > > > Sorry, i think the serial driver IRQ is level triggered :) That's actually incorrect. Serial devices are (were) connected to the old ISA PICs which are definitely edge triggered. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core