From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: [v2] dmaengine: axi-dmac: Request IRQ with IRQF_SHARED From: Moritz Fischer Message-Id: Date: Fri, 27 Apr 2018 08:15:32 -0700 To: Vinod Koul Cc: Lars-Peter Clausen , Linux Kernel Mailing List , dmaengine@vger.kernel.org, dan.j.williams@intel.com List-ID: SGkgVmlub2QsCgpPbiBGcmksIEFwciAyNywgMjAxOCBhdCAxMjowOCBBTSwgVmlub2QgS291bCA8 dmlub2Qua291bEBpbnRlbC5jb20+IHdyb3RlOgo+IE9uIEZyaSwgQXByIDI3LCAyMDE4IGF0IDA4 OjUzOjM5QU0gKzAyMDAsIExhcnMtUGV0ZXIgQ2xhdXNlbiB3cm90ZToKPj4gT24gMDQvMjcvMjAx OCAwNzoxMSBBTSwgVmlub2QgS291bCB3cm90ZToKPj4gPiBPbiBUaHUsIEFwciAyNiwgMjAxOCBh dCAxMDo0MDowMEFNIC0wNzAwLCBNb3JpdHogRmlzY2hlciB3cm90ZToKPj4gPj4gUmVxdWVzdCBJ UlEgd2l0aCBJUlFGX1NIQVJFRCBmbGFnLiBUaGlzIHdvcmtzIHNpbmNlIHRoZSBpbnRlcnJ1cHQK Pj4gPj4gaGFuZGxlciBhbHJlYWR5IGNoZWNrcyBpZiB0aGVyZSBpcyBhbiBhY3R1YWwgSVJRIHBl bmRpbmcgYW5kIHJldHVybnMKPj4gPj4gSVJRX05PTkUgb3RoZXJ3aXNlLgo+PiA+Cj4+ID4gaG1t bSB3aGF0IGFyZSB3ZSB0cnlpbmcgdG8gZml4IGhlcmU/IElzIHlvdXIgZGV2aWNlIG9uIGEgc2hh cmVkIGxpbmUgb3Igbm90Pwo+Pgo+PiBJUlFGX1NIQVJFRCBkb2VzIG5vdCBtZWFuIHRoYXQgdGhl IElSUSBpcyBvbiBhIHNoYXJlZCBsaW5lLiBJdCBtZWFucyB0aGF0Cj4+IHRoZSBkcml2ZXIgY2Fu IGhhbmRsZSBpdCBpZiB0aGUgSVJRIGlzIG9uIGEgc2hhcmVkIGxpbmUuIFNpbmNlIHRoZSBkcml2 ZXIKPj4gY2FuIGhhbmRsZSBpdCBzZXR0aW5nIHRoZSBmbGFnIGlzIGEgZ29vZCBpZGVhIHNpbmNl IHRoaXMgZW5hYmxlcyB1c2VjYXNlcwo+PiB3aGVyZSB0aGUgbGluZSBpcyBzaGFyZWQuCj4KPiBZ ZXMgdGhhdCBpcyBjb3JyZWN0IGluZGVlZCwgYnV0IHdoYXQgaXMgdGhlIG1vdGl2YXRpb24gZm9y IHRoZSBjaGFuZ2UuCj4KPiBJZiB5b3UgbmV2ZXIgZXhwZWN0IHRoaXMgdG8gYmUgaW4gc2hhcmVk IGVudmlyb25tZW50IHdoeSB0byBkbyB0aGlzPwo+IFNvcnJ5IGJ1dCAiaXQgd29ya3MiIGlzIG5v dCBhIGdvb2QgZW5vdWdoIHJlYXNvbiBmb3IgdGhpcyBjaGFuZ2UsIHRvIGVuYWJsZQo+IHVzZWNh c2VzIHdoZXJlIHRoZSBsaW5lIGlzIHNoYXJlZCBpcyBhIGdvb2QgcmVhc29uIDopCgpSZW1lbWJl ciwgdGhpcyBpcyBhbiBGUEdBIHNvZnQgY29yZS4gSSBoYXBwZW4gdG8gaGF2ZSBhIGRlc2lnbiBb MV0gd2hlcmUgaXQKaXMgaG9va2VkIHVwIHdpdGggbXVsdGlwbGUgb2YgdGhlbSBvbiBvbmUgSVJR IGxpbmUsIHNvIHRvIG1ha2UgdGhpcyB3b3JrLApJIG5lZWQgdGhpcyBjaGFuZ2UuCgpUaGFua3Ms CgpNb3JpdHoKClsxXSBodHRwczovL3d3dy5ldHR1cy5jb20vcHJvZHVjdC9kZXRhaWxzL1VTUlAt TjMxMAotLS0KVG8gdW5zdWJzY3JpYmUgZnJvbSB0aGlzIGxpc3Q6IHNlbmQgdGhlIGxpbmUgInVu c3Vic2NyaWJlIGRtYWVuZ2luZSIgaW4KdGhlIGJvZHkgb2YgYSBtZXNzYWdlIHRvIG1ham9yZG9t b0B2Z2VyLmtlcm5lbC5vcmcKTW9yZSBtYWpvcmRvbW8gaW5mbyBhdCAgaHR0cDovL3ZnZXIua2Vy bmVsLm9yZy9tYWpvcmRvbW8taW5mby5odG1sCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933750AbeD0PPh (ORCPT ); Fri, 27 Apr 2018 11:15:37 -0400 Received: from mail-qt0-f173.google.com ([209.85.216.173]:42805 "EHLO mail-qt0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933223AbeD0PPd (ORCPT ); Fri, 27 Apr 2018 11:15:33 -0400 X-Google-Smtp-Source: AB8JxZqy79WX/YIayGvG2SA/O641PWz3VHSb3rI/6DH42SEiJhbcpnPAZ//aegF8QUv8tq90jXIKpCY+no9WEt7iiv0= MIME-Version: 1.0 In-Reply-To: <20180427070830.GC6014@localhost> References: <20180426174000.12008-1-mdf@kernel.org> <20180427051115.GX6014@localhost> <748ffc14-de12-c11e-eb12-65c599fe5f4e@metafoo.de> <20180427070830.GC6014@localhost> From: Moritz Fischer Date: Fri, 27 Apr 2018 08:15:32 -0700 Message-ID: Subject: Re: [PATCH v2] dmaengine: axi-dmac: Request IRQ with IRQF_SHARED To: Vinod Koul Cc: Lars-Peter Clausen , Linux Kernel Mailing List , dmaengine@vger.kernel.org, dan.j.williams@intel.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks, Moritz [1] https://www.ettus.com/product/details/USRP-N310