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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 57636C433ED for ; Fri, 9 Apr 2021 16:08:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35E5160C3D for ; Fri, 9 Apr 2021 16:08:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233902AbhDIQI1 (ORCPT ); Fri, 9 Apr 2021 12:08:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50140 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233657AbhDIQI0 (ORCPT ); Fri, 9 Apr 2021 12:08:26 -0400 Received: from mail.pqgruber.com (mail.pqgruber.com [IPv6:2a05:d014:575:f70b:4f2c:8f1d:40c4:b13e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF5B9C061761; Fri, 9 Apr 2021 09:08:13 -0700 (PDT) Received: from workstation.tuxnet (213-47-165-233.cable.dynamic.surfer.at [213.47.165.233]) by mail.pqgruber.com (Postfix) with ESMTPSA id 35805C725C8; Fri, 9 Apr 2021 18:08:12 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pqgruber.com; s=mail; t=1617984492; bh=Np0R8jz8X4f7v3vdRWj+57iPcgTXHXb9XIYeOfW1UjU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BVZ9FKGYwtfh+ksPg4LV9T5cfz/S7UWpckmigqBJUkQ++69eYSiEdVfd6NDGrQC1G LKm+7ywk4nXYWJH2ncU5dth8JOXifkKfFBNZ8FnlqCjrRm5hrCdJpaZk6JL1kA3KI1 bKVi50TYuyy6nI4j+lkYZ15TzPyAi80Rum4Y651I= Date: Fri, 9 Apr 2021 18:08:10 +0200 From: Clemens Gruber To: Thierry Reding Cc: linux-pwm@vger.kernel.org, Sven Van Asbroeck , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 3/8] pwm: pca9685: Improve runtime PM behavior Message-ID: References: <20210406164140.81423-1-clemens.gruber@pqgruber.com> <20210406164140.81423-3-clemens.gruber@pqgruber.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Fri, Apr 09, 2021 at 03:03:20PM +0200, Thierry Reding wrote: > On Tue, Apr 06, 2021 at 06:41:35PM +0200, Clemens Gruber wrote: > > The chip does not come out of POR in active state but in sleep state. > > To be sure (in case the bootloader woke it up) we force it to sleep in > > probe. > > > > On kernels without CONFIG_PM, we wake the chip in .probe and put it to > > sleep in .remove. > > > > Signed-off-by: Clemens Gruber > > --- > > Changes since v6: > > - Improved !CONFIG_PM handling (wake it up without putting it to sleep > > first) > > > > drivers/pwm/pwm-pca9685.c | 26 +++++++++++++++++++------- > > 1 file changed, 19 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c > > index d4474c5ff96f..0bcec04b138a 100644 > > --- a/drivers/pwm/pwm-pca9685.c > > +++ b/drivers/pwm/pwm-pca9685.c > > @@ -474,13 +474,18 @@ static int pca9685_pwm_probe(struct i2c_client *client, > > return ret; > > } > > > > - /* The chip comes out of power-up in the active state */ > > - pm_runtime_set_active(&client->dev); > > - /* > > - * Enable will put the chip into suspend, which is what we > > - * want as all outputs are disabled at this point > > - */ > > - pm_runtime_enable(&client->dev); > > + if (IS_ENABLED(CONFIG_PM)) { > > This looks odd to me. I've seen similar constructs, but they usually go > something like this (I think): > > pm_runtime_enable(&client->dev); > > if (!pm_runtime_enabled(&client->dev)) { > /* resume device */ > } > > Which I guess in your would be somewhat the opposite and it wouldn't > actually resume the device but rather put it to sleep. Yes, I wanted to keep it in sleep mode if runtime PM is supported (to be woken up later) and otherwise just wake it up in probe. > > Perhaps something like this: > > pm_runtime_enable(&client->dev); > > if (pm_runtime_enabled(&client->dev)) { > pca9685_set_sleep_mode(pca, true); > pm_runtime_set_suspended(&client->dev); > } else { > /* wake the chip up on non-PM environments */ > pca9685_set_sleep_mode(pca, false); > } > > ? I think that's slightly more correct than your original because it > takes into account things like sysfs power control and such. It also > doesn't rely on the config option alone but instead uses the runtime > PM API to achieve this more transparently. Ah, yes, I missed the fact that runtime could be disabled 'at runtime' via sysfs as well, so yes, that's more correct and pm_runtime_enabled will just return false if !CONFIG_PM, so that should work as well. Thanks, Clemens