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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5211C4332F for ; Thu, 3 Nov 2022 12:06:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231474AbiKCMGf (ORCPT ); Thu, 3 Nov 2022 08:06:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35252 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229700AbiKCMG2 (ORCPT ); Thu, 3 Nov 2022 08:06:28 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id BA3A312A88 for ; Thu, 3 Nov 2022 05:06:27 -0700 (PDT) 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 9C06D1FB; Thu, 3 Nov 2022 05:06:33 -0700 (PDT) Received: from e120937-lin (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 974343F703; Thu, 3 Nov 2022 05:06:25 -0700 (PDT) Date: Thu, 3 Nov 2022 12:06:15 +0000 From: Cristian Marussi To: Sudeep Holla Cc: Florian Fainelli , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.quinlan@broadcom.com, Jonathan.Cameron@huawei.com, etienne.carriere@linaro.org, vincent.guittot@linaro.org, souvik.chakravarty@arm.com, wleavitt@marvell.com, peter.hilber@opensynergy.com, nicola.mazzucato@arm.com, tarek.el-sherbiny@arm.com, quic_kshivnan@quicinc.com Subject: Re: [PATCH v4 0/11] Introduce a unified API for SCMI Server testing Message-ID: References: <20221019204626.3813043-1-cristian.marussi@arm.com> <20221103112147.rq2v7dwte577kmb4@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221103112147.rq2v7dwte577kmb4@bogus> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 03, 2022 at 11:21:47AM +0000, Sudeep Holla wrote: > On Fri, Oct 28, 2022 at 07:38:25PM -0700, Florian Fainelli wrote: > > Hi Christian, > > > > On 10/19/2022 1:46 PM, Cristian Marussi wrote: > > [snip] > > > > > In V2 the runtime enable/disable switching capability has been removed > > > (for now) since still not deemed to be stable/reliable enough: as a > > > consequence when SCMI Raw support is compiled in, the regular SCMI stack > > > drivers are now inhibited permanently for that Kernel. > > > > For our platforms (ARCH_BRCMSTB) we would need to have the ability to start > > with the regular SCMI stack to satisfy if nothing else, all clock consumers > > otherwise it makes it fairly challenging for us to boot to a prompt as we > > purposely turn off all unnecessary peripherals to conserve power. We could > > introduce a "full on" mode to remove the clock provider dependency, but I > > suspect others on "real" silicon may suffer from the same short comings. > > > > Fair enough. But if we are doing SCMI firmware testing or conformance via > the $subject proposed way, can these drivers survive if the userspace do > a random or a torture test changing the clock configurations ? Not sure > how to deal with that as the intention here is to do the testing from the > user-space and anything can happen. How do we avoid bring the entire system > down while doing this testing. Can we unbind all the drivers using scmi on > your platform ? I guess no. Let me know. > > > Once user-space is reached, I suppose we could find a way to unbind from all > > SCMI consumers, and/or ensure that runtime PM is disabled, cpufreq is in a > > governor that won't do any active frequency switching etc. > > > > What do you think? > > Yes, Cristian always wanted to support that but I am the one trying to > convince him not to unless there is a strong requirement for it. You seem > to suggest that you have such a requirement, but that just opens loads of > questions and how to we deal with that. Few of them are as stated above, I > need to recall all the conversations I had with Cristian around that and why > handling it may be bit complex. :D ... I really even more like the idea of enabling on demand full coexistence so that I completely delegate to the users to manually deal with possible interferences at runtime and drop any liabilities if someone shoots himself in the foot :P ... jokes apart I'll post today a V5 with a few fixes and and an optional coexistence mode so that Florian can experiment and see how much is feasible to operate in this way by manually unbinding/re-configuring SCMI behaviour at runtime before starting tests and not kill the system on something like ARCH_BRCMSTB platforms. Thanks, Cristian