From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E529615279C for ; Thu, 9 May 2024 13:13:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715260414; cv=none; b=Hy0+4mPCZ41N+yiZz8YO5B4hy5QAAHcfBAulMLibtb00vWsZ45/y4dkKQN0vc6CTX2AwYcuW5d7z250ruOgxqK+MKgAvKjLT+GdZqSjNdTazVL4SfcbE5TcuQpOTUWemInmE3epjGRayBKbHGYSOcp8FDTWn90PY2pGV8S7KCY0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715260414; c=relaxed/simple; bh=xHpFBlv53Nwt0GiZ9lqlDTEdIgEYX00qGzSU6Nx3jLM=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=hDlb0L9JS3hikNUWtpSIeRIA+OMXGg265NC2ALbzqP+8gAAjTAXQvPpH2qC/WkQ1djhk6/jNYdGLceYdoGj4REhD4R/ceGReS8OtVG2IELVp6fBkocNdVJILP2qgVtEFT8gAshAY1/xSR9qu/pCS14fbQbsfUIfoWwEWhcnmm9k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.216]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4VZsnZ3FDXz6JB4V; Thu, 9 May 2024 21:10:26 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id C7108140C98; Thu, 9 May 2024 21:13:28 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Thu, 9 May 2024 14:13:28 +0100 Date: Thu, 9 May 2024 14:13:26 +0100 From: Jonathan Cameron To: CC: , , , Jean-Baptiste Maneyrol Subject: Re: [PATCH] iio: imu: inv_icm42600: add support of accel low-power mode Message-ID: <20240509141326.00000684@Huawei.com> In-Reply-To: <20240507103056.291643-1-inv.git-commit@tdk.com> References: <20240507103056.291643-1-inv.git-commit@tdk.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml500005.china.huawei.com (7.191.163.240) To lhrpeml500005.china.huawei.com (7.191.163.240) On Tue, 7 May 2024 10:30:56 +0000 inv.git-commit@tdk.com wrote: > From: Jean-Baptiste Maneyrol > > Add channel attributes "power_mode" and "power_mode_available" for > setting accel power mode (low-noise or low-power). > > Differents ODRs and filter are possible depending on the power mode. > Thus make ODRs and filter dynamic and check values when applying. Hi Jean-Baptiste No Sign-off? We have never provided this sort of control because it's near impossible for user space to know what to do with it. Various attempts happened in the past to provide enough info to userspace, but didn't succeed because what low power means is incredibly chip dependent. As a general rule everyone wants low power, but at 0 perf cost :) What are the results of low power mode? Normally it maps as something we can enable when some other set of states is set or automatically control based on how often the device is being accessed etc. For example, what do we loose by choosing this mode for everything below 200Hz? I see there is some reference to 'low noise' - what does that actually mean for this device? Is it oversampling or running lower resolution on the ADCs? If so those are the things to look at as ways to control this. Choose lowest power to meet a given set of requirements. Jonathan