From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933157AbWKSUY4 (ORCPT ); Sun, 19 Nov 2006 15:24:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933160AbWKSUYz (ORCPT ); Sun, 19 Nov 2006 15:24:55 -0500 Received: from h155.mvista.com ([63.81.120.155]:55725 "EHLO imap.sh.mvista.com") by vger.kernel.org with ESMTP id S933157AbWKSUYz (ORCPT ); Sun, 19 Nov 2006 15:24:55 -0500 Message-ID: <4560BDF5.400@ru.mvista.com> Date: Sun, 19 Nov 2006 23:26:29 +0300 From: Sergei Shtylyov Organization: MontaVista Software Inc. User-Agent: Mozilla/5.0 (X11; U; Linux i686; rv:1.7.2) Gecko/20040803 X-Accept-Language: ru, en-us, en-gb MIME-Version: 1.0 To: Benjamin Herrenschmidt Cc: Ingo Molnar , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, dwalker@mvista.com Subject: Re: [PATCH] 2.6.18-rt7: PowerPC: fix breakage in threaded fasteoi type IRQ handlers References: <200611192243.34850.sshtylyov@ru.mvista.com> <1163966437.5826.99.camel@localhost.localdomain> <20061119200650.GA22949@elte.hu> <1163967590.5826.104.camel@localhost.localdomain> In-Reply-To: <1163967590.5826.104.camel@localhost.localdomain> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello. Benjamin Herrenschmidt wrote: >>* Benjamin Herrenschmidt wrote: >>>Wait wait wait .... Can somebody (Ingo ?) explain me why the fasteoi >>>handler is being changed and what is the rationale for adding an ack >>>that was not necessary before ? >>dont worry, it's -rt only stuff. > Still, I'm curious :-) Besides, there have been people talking about > having -rt work on ppc64 so ... > What do you need an ack() for on fasteoi ? On all fasteoi controllers I > have, ack is implicit by obtaining the vector number and all there is is > an eoi... I must not that this whole ack() vs eoi() stuff is misleading. For example, in 8259 driver, mask_ack() method actually sends EOI to PIC, not ACK's an IRQ -- the actual ACK is implicit on x86 and is used to read the interrupt vector form 8259 on PPC. So, IMO, there probably should only have been either ack() or eoi() method in the first place. Though I'm not familiar with ARM from which genirq stuff originated... > Cheers, > Ben. WBR, Sergei