Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753243AbaBJTLx (ORCPT ); Mon, 10 Feb 2014 14:11:53 -0500 Received: from smtp.codeaurora.org ([198.145.11.231]:41656 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752423AbaBJTLv (ORCPT ); Mon, 10 Feb 2014 14:11:51 -0500 Date: Mon, 10 Feb 2014 13:09:34 -0600 From: Josh Cartwright To: Rob Herring Cc: Arnd Bergmann , Courtney Cavin , s-anna@ti.com, Rob Herring , "Wysocki, Rafael J" , Mark Langsdorf , Tony Lindgren , omar.ramirez@copitl.com, Greg Kroah-Hartman , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Rob Landley , "linux-doc@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC 1/6] mailbox: add core framework Message-ID: <20140210190934.GA841@joshc.qualcomm.com> References: <1391820619-25487-1-git-send-email-courtney.cavin@sonymobile.com> <1391820619-25487-2-git-send-email-courtney.cavin@sonymobile.com> <4706525.lB7VmvWQMJ@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 10, 2014 at 11:52:05AM -0600, Rob Herring wrote: > On Mon, Feb 10, 2014 at 8:11 AM, Arnd Bergmann wrote: > > On Friday 07 February 2014 16:50:14 Courtney Cavin wrote: [..] > >> +int mbox_channel_notify(struct mbox_channel *chan, > >> + const void *data, unsigned int len) > >> +{ > >> + return atomic_notifier_call_chain(&chan->notifier, len, (void *)data); > >> +} > >> +EXPORT_SYMBOL(mbox_channel_notify); > > > > What is the reason to use a notifier chain here? Isn't a simple > > callback function pointer enough? I would expect that each mailbox > > can have exactly one consumer, not multiple ones. > > It probably can be a callback, but there can be multiple consumers. It > was only a notifier on the pl320 as there was no framework at the time > and to avoid creating custom interfaces between drivers. On highbank > for example, we can asynchronously receive the events for temperature > change, power off, and reset. So either there needs to be an event > demux somewhere or callbacks have to return whether they handled an > event or not. I'm not familiar with highbank IPC, but with these requirements should the mailbox core even bother with asynchronous notifier chain? It sounds like a better fit might be for the mailbox core to implement a proper adapter-specific irqdomain and used a chained irq handler to demux (or have consumers request with IRQF_SHARED in the shared case). -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- 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/