From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751625AbdGZTNz convert rfc822-to-8bit (ORCPT ); Wed, 26 Jul 2017 15:13:55 -0400 Received: from unicorn.mansr.com ([81.2.72.234]:34160 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751595AbdGZTNv (ORCPT ); Wed, 26 Jul 2017 15:13:51 -0400 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Florian Fainelli Cc: Marc Gonzalez , Doug Berger , Thomas Gleixner , Marc Zyngier , Jason Cooper , LKML , Linux ARM , Mason Subject: Re: [PATCH v3] irqchip/tango: Don't use incorrect irq_mask_ack callback References: <20170719190734.18566-1-opendmb@gmail.com> <20170719190734.18566-3-opendmb@gmail.com> <7a51555f-8191-9ebd-1f30-7c20f6db9d3f@sigmadesigns.com> <8d29fec9-35b8-c33b-3091-3e9a51c99ed7@gmail.com> <6f0092f7-692f-4a15-1d95-40f4e59c8585@sigmadesigns.com> <3b858e14-0da1-d4aa-eb84-f136ece8c2a6@gmail.com> Date: Wed, 26 Jul 2017 20:13:47 +0100 In-Reply-To: <3b858e14-0da1-d4aa-eb84-f136ece8c2a6@gmail.com> (Florian Fainelli's message of "Wed, 26 Jul 2017 11:20:05 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Florian Fainelli writes: > On 07/25/2017 06:29 AM, Måns Rullgård wrote: >> Marc Gonzalez writes: >> >>> On 25/07/2017 15:16, Måns Rullgård wrote: >>> >>>> What happened to the patch adding the proper combined function? >>> >>> It appears you're not CCed on v2. >>> >>> https://patchwork.kernel.org/patch/9859799/ >>> >>> Doug wrote: >>>> Yes, you understand correctly. The irq_mask_ack method is entirely >>>> optional and I assume that is why this issue went undetected for so >>>> long; however, it is slightly more efficient to combine the functions >>>> (even if the ack is unnecessary) which is why I chose to do so for my >>>> changes to the irqchip-brcmstb-l2 driver where I first discovered this >>>> issue. How much value the improved efficiency has is certainly >>>> debatable, but interrupt handling is one area where people might care >>>> about such a small difference. As the irqchip-tango driver maintainer >>>> you are welcome to decide whether or not the irq_mask_ack method makes >>>> sense to you. >>> >>> My preference goes to leaving the irq_mask_ack callback undefined, >>> and let the irqchip framework use irq_mask and irq_ack instead. >> >> Why would you prefer the less efficient way? >> > > Same question here, that does not really make sense to me. > > The whole point of this patch series is to have a set of efficient and > bugfree (or nearly) helper functions that drivers can rely on, are you > saying that somehow using irq_mask_and_ack is exposing a bug in the > tango irqchip driver and using the separate functions does not expose > this bug? There is currently a bug in that the function used doesn't do what its name implies which can't be good. Using the separate mask and ack functions obviously works, but combining them saves a lock/unlock sequence. The correct combined function has already been written, so I see no reason not to use it. -- Måns Rullgård