Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753535AbdCAWjf (ORCPT ); Wed, 1 Mar 2017 17:39:35 -0500 Received: from mail-wr0-f177.google.com ([209.85.128.177]:34849 "EHLO mail-wr0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753516AbdCAWjc (ORCPT ); Wed, 1 Mar 2017 17:39:32 -0500 MIME-Version: 1.0 In-Reply-To: <20170301184333.GA12197@obsidianresearch.com> References: <20170301115116.19696-1-enric.balletbo@collabora.com> <20170301135429.GF28874@leverpostej> <20170301184333.GA12197@obsidianresearch.com> From: Sonny Rao Date: Wed, 1 Mar 2017 14:39:09 -0800 X-Google-Sender-Auth: tBBEJIvL1P1W-FSnOP2NN6kNOss Message-ID: Subject: Re: [tpmdd-devel] [PATCH] tpm: do not suspend/resume if power stays on To: Jason Gunthorpe Cc: Mark Rutland , Enric Balletbo i Serra , "linux-kernel@vger.kernel.org" , Rob Herring , tpmdd-devel@lists.sourceforge.net Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 990 Lines: 27 On Wed, Mar 1, 2017 at 10:43 AM, Jason Gunthorpe wrote: >> > +Optional properties: >> > +- powered-while-suspended: present when the TPM is left powered on between >> > + suspend and resume (makes the suspend/resume callbacks do nothing). >> >> This reads like configuration rather than a HW property. > > I read this to mean the HW does not cut power to the TPM when Linux > does 'suspend'. That's correct, it is a hardware property describing whether power is removed during suspend. > > We recently added global suspend/resume callbacks to the TPM > core. Those call backs do not power off the TPM, they just prepare its > internal state to loose power to the chip. Skipping that process on > hardware that does not power-off the TPM makes sense to me. > > But, Sonny, perhaps this should be a global flag in tpm_chip, not a > per-interface-driver override? It's a property of the board design not the chip -- maybe I'm misunderstanding? > > Jason