From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86DA4C433E0 for ; Thu, 4 Jun 2020 09:20:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 60EA5207F9 for ; Thu, 4 Jun 2020 09:20:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726936AbgFDJU6 (ORCPT ); Thu, 4 Jun 2020 05:20:58 -0400 Received: from foss.arm.com ([217.140.110.172]:42272 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726444AbgFDJU6 (ORCPT ); Thu, 4 Jun 2020 05:20:58 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 91DBC55D; Thu, 4 Jun 2020 02:20:57 -0700 (PDT) Received: from bogus (unknown [10.37.12.7]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6B4FA3F6CF; Thu, 4 Jun 2020 02:20:55 -0700 (PDT) Date: Thu, 4 Jun 2020 10:20:52 +0100 From: Sudeep Holla To: Jassi Brar Cc: Viresh Kumar , Rob Herring , Arnd Bergmann , Frank Rowand , Bjorn Andersson , Vincent Guittot , linux-arm-kernel , Devicetree List , Linux Kernel Mailing List Subject: Re: [RFC] dt-bindings: mailbox: add doorbell support to ARM MHU Message-ID: <20200604092052.GD8814@bogus> References: <0a50f0cf5593baeb628dc8606c523665e5e2ae6c.1589519600.git.viresh.kumar@linaro.org> <20200528192005.GA494874@bogus> <20200529040758.kneg2j4n3gxh2rfv@vireshk-i7> <20200603180435.GB23722@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 03, 2020 at 01:32:42PM -0500, Jassi Brar wrote: > On Wed, Jun 3, 2020 at 1:04 PM Sudeep Holla wrote: > > > > On Fri, May 29, 2020 at 09:37:58AM +0530, Viresh Kumar wrote: > > > On 28-05-20, 13:20, Rob Herring wrote: > > > > Whether Linux > > > > requires serializing mailbox accesses is a separate issue. On that side, > > > > it seems silly to not allow driving the h/w in the most efficient way > > > > possible. > > > > > > That's exactly what we are trying to say. The hardware allows us to > > > write all 32 bits in parallel, without any hardware issues, why > > > shouldn't we do that ? The delay (which Sudeep will find out, he is > > > facing issues with hardware access because of lockdown right now) > > > > OK, I was able to access the setup today. I couldn't reach a point > > where I can do measurements as the system just became unusable with > > one physical channel instead of 2 virtual channels as in my patches. > > > > My test was simple. Switch to schedutil and read sensors periodically > > via sysfs. > > > > arm-scmi firmware:scmi: message for 1 is not expected! > > > This sounds like you are not serialising requests on a shared channel. > Can you please also share the patch? OK, I did try with a small patch initially and then realised we must hit issue with mainline as is. Tried and the behaviour is exact same. All I did is removed my patches and use bit[0] as the signal. It doesn't matter as writes to the register are now serialised. Oh, the above message comes when OS times out in advance while firmware continues to process the old request and respond. The trace I sent gives much better view of what's going on. -- Regards, Sudeep