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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 0008AC4BA13 for ; Wed, 26 Feb 2020 17:09:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CCE43206E6 for ; Wed, 26 Feb 2020 17:09:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728240AbgBZRJo (ORCPT ); Wed, 26 Feb 2020 12:09:44 -0500 Received: from muru.com ([72.249.23.125]:57782 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727240AbgBZRJn (ORCPT ); Wed, 26 Feb 2020 12:09:43 -0500 Received: from atomide.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 62B8F8022; Wed, 26 Feb 2020 17:10:27 +0000 (UTC) Date: Wed, 26 Feb 2020 09:09:39 -0800 From: Tony Lindgren To: Lokesh Vutla Cc: Daniel Lezcano , Thomas Gleixner , Linux OMAP Mailing List , linux-kernel@vger.kernel.org, narmstrong@baylibre.com, Sekhar Nori , Tero Kristo Subject: Re: [PATCH 1/2] clocksource: timer-ti-dm: Do not restore context on every timer enable Message-ID: <20200226170939.GQ37466@atomide.com> References: <20200224050753.17784-1-lokeshvutla@ti.com> <20200224050753.17784-2-lokeshvutla@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200224050753.17784-2-lokeshvutla@ti.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Lokesh Vutla [200224 05:09]: > omap_dm_timer_enable() restores the entire context(including counter) > based on 2 conditions: > - If get_context_loss_count is populated and context is lost. > - If get_context_loss_count is not populated update unconditionally. > > Case2 has a side effect of updating the counter register even though > context is not lost. When timer is configured in pwm mode, this is > causing undesired behaviour in the pwm period. So restore context only > if get_context_loss_count is populated and context is actually lost. Sounds like this will break things. We have get_context_loss_count() only on omap4 and later, and even that was only partially implemented from what I recall. To mee it seems the right thing to do here is to save and restore context on CPU_CLUSTER_PM_ENTER and CPU_CLUSTER_PM_EXIT. And I'd just get rid of the partially implemented custom calls to get_context_loss_count(). See for example a recent patch on removing the legacy SDMA code for CPU_CLUSTER_PM_ENTER in commit d2f924879e19 ("thermal: ti-soc-thermal: Enable addition power management"). Then if we really need to add checks for context lost at some point, that can be implemented via reset_control_status() returning -ENOLINK or something similar. Regards, Tony