From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933624AbeD0PSn (ORCPT ); Fri, 27 Apr 2018 11:18:43 -0400 Received: from www381.your-server.de ([78.46.137.84]:42907 "EHLO www381.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933111AbeD0PSk (ORCPT ); Fri, 27 Apr 2018 11:18:40 -0400 Subject: Re: [PATCH v2] dmaengine: axi-dmac: Request IRQ with IRQF_SHARED To: Moritz Fischer , Vinod Koul Cc: Linux Kernel Mailing List , dmaengine@vger.kernel.org, dan.j.williams@intel.com References: <20180426174000.12008-1-mdf@kernel.org> <20180427051115.GX6014@localhost> <748ffc14-de12-c11e-eb12-65c599fe5f4e@metafoo.de> <20180427070830.GC6014@localhost> From: Lars-Peter Clausen Message-ID: <716956a2-a4f4-9cbd-8761-8db477f1dfc0@metafoo.de> Date: Fri, 27 Apr 2018 17:18:29 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: lars@metafoo.de Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/27/2018 05:15 PM, Moritz Fischer wrote: > Hi Vinod, > > On Fri, Apr 27, 2018 at 12:08 AM, Vinod Koul wrote: >> On Fri, Apr 27, 2018 at 08:53:39AM +0200, Lars-Peter Clausen wrote: >>> On 04/27/2018 07:11 AM, Vinod Koul wrote: >>>> On Thu, Apr 26, 2018 at 10:40:00AM -0700, Moritz Fischer wrote: >>>>> Request IRQ with IRQF_SHARED flag. This works since the interrupt >>>>> handler already checks if there is an actual IRQ pending and returns >>>>> IRQ_NONE otherwise. >>>> >>>> hmmm what are we trying to fix here? Is your device on a shared line or not? >>> >>> IRQF_SHARED does not mean that the IRQ is on a shared line. It means that >>> the driver can handle it if the IRQ is on a shared line. Since the driver >>> can handle it setting the flag is a good idea since this enables usecases >>> where the line is shared. >> >> Yes that is correct indeed, but what is the motivation for the change. >> >> If you never expect this to be in shared environment why to do this? >> Sorry but "it works" is not a good enough reason for this change, to enable >> usecases where the line is shared is a good reason :) > > Remember, this is an FPGA soft core. I happen to have a design [1] where it > is hooked up with multiple of them on one IRQ line, so to make this work, > I need this change. I think what Vinod is asking for is a change to the commit message saying that "this change enables the driver to be used with devices where the interrupt line is shared".