From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755526AbdKBKvi (ORCPT ); Thu, 2 Nov 2017 06:51:38 -0400 Received: from foss.arm.com ([217.140.101.70]:57838 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755193AbdKBKvg (ORCPT ); Thu, 2 Nov 2017 06:51:36 -0400 Cc: Jassi Brar , Sudeep Holla , Linux Kernel Mailing List , "linux-arm-kernel@lists.infradead.org" , Arnd Bergmann Subject: Re: [PATCH] mailbox: add support for doorbell/signal mode controllers To: Bjorn Andersson References: <1509553964-4451-1-git-send-email-sudeep.holla@arm.com> <20171101221217.GA28761@minitux> From: Sudeep Holla Organization: ARM Message-ID: <9c0a0af0-6a2d-4394-a274-2e52ea65845d@arm.com> Date: Thu, 2 Nov 2017 10:51:33 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171101221217.GA28761@minitux> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/11/17 22:12, Bjorn Andersson wrote: > On Wed 01 Nov 11:03 PDT 2017, Jassi Brar wrote: >> On Wed, Nov 1, 2017 at 10:02 PM, Sudeep Holla wrote: > [..] >>> >>> This is rough idea I have on extending mailbox interface to support >>> the doorbell requirements. >>> >> What doorbell requirements does the api not support? >> QComm's APCS IPC is what you call a "doorbell" controller and is >> already supported by the API. It could run SCMI even easier than MHU >> (your controller). >> > > I agree; from a mbox consumer perspective a doorbell should be a mailbox > channel that when signalled will ring the bell, i.e. the message is not > significant and should not be provided by the client. > Exactly. > If the message is significant and is not derived from the mailbox > channel (e.g. channel id -> bit in register) it is not a mailbox > doorbell, it's s regular mailbox used as a doorbell. > Agreed, in my case(ARM MHU) it's indeed a register bit. > > The potential improvement I see in the Qualcomm case is to wrap the > mbox_send_message(chan, NULL); mbox_client_txdone(chan, 0); calls in one > simple "mbox_ring_door_bell(chan)" - but I haven't investigated the > validity of this as a generic function. > Yes that's exactly what I want to do as we make progress with this patch. For that we find need to add send_signal(chan), instead of send_data(chan, data). -- Regards, Sudeep