Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751637AbWLMW1N (ORCPT ); Wed, 13 Dec 2006 17:27:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751638AbWLMW1N (ORCPT ); Wed, 13 Dec 2006 17:27:13 -0500 Received: from www.osadl.org ([213.239.205.134]:51952 "EHLO mail.tglx.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751636AbWLMW1M (ORCPT ); Wed, 13 Dec 2006 17:27:12 -0500 Subject: Re: [GIT PATCH] more Driver core patches for 2.6.19 From: Thomas Gleixner Reply-To: tglx@linutronix.de To: Benjamin Herrenschmidt Cc: Linus Torvalds , Greg KH , Andrew Morton , linux-kernel@vger.kernel.org In-Reply-To: <1166048081.11914.208.camel@localhost.localdomain> References: <20061213195226.GA6736@kroah.com> <1166044471.11914.195.camel@localhost.localdomain> <1166048081.11914.208.camel@localhost.localdomain> Content-Type: text/plain Date: Wed, 13 Dec 2006 23:30:55 +0100 Message-Id: <1166049055.29505.47.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1033 Lines: 30 On Thu, 2006-12-14 at 09:14 +1100, Benjamin Herrenschmidt wrote: > the edge flow is easy. the level one is: > > - IRQ happens > - kernel handler masks it and queue a msg for userland > - later on, userland gets the message, talks to the device, > (MMAP'ed mmio, acks the interrupt on the device itself) and > does an ioctl/syscall/write/whatever to tell kernel it's done > - kernel unmasks it. That's simply not true. - IRQ happens - kernel handler runs and masks the chip irq, which removes the IRQ request - user space message get queued or waiting reader woken - kernel handler returns IRQ_HANDLED, which reenables the irq in the PIC - user space handles the device - user space reenables the device irq No need for an ioctl. Neither for edge nor for level irqs. tglx - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/