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 56D1FEE14C3 for ; Wed, 6 Sep 2023 19:55:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241784AbjIFTzk (ORCPT ); Wed, 6 Sep 2023 15:55:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235378AbjIFTzh (ORCPT ); Wed, 6 Sep 2023 15:55:37 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1021595 for ; Wed, 6 Sep 2023 12:55:33 -0700 (PDT) Received: from [192.168.1.90] (unknown [81.18.92.207]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: cristicc) by madras.collabora.co.uk (Postfix) with ESMTPSA id 37D2566071C9; Wed, 6 Sep 2023 20:55:31 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1694030131; bh=2KxpuPLY69OjJIbp80A3wlXtunQ/auxoaIoxRETzcuo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=bUF3pS9kNsMeA4GBVV8oVlUYwxPRUWLBPxbqecxYcS0mYabXunx6WVfxjTL4ho4/F yuOb4doBJcKy6J2Vcp7RQvyMDkTOYJ2/aT+386cgbUwO4C0C+p25A0Z09jMKvxvewV lbth5G93KdU0O9RmP3klpasFQUR7LikYGpIKrHtqo8pzoWD3EuZuPtwPQsuwzgwlAS cT6iJbx6Z9zHrnlvn7vtvdASjk7sb42vKKinJiWmZPGluUiowWKvhyi+gpAHhOxk1p onlaJyYm1rY9CxiHXQEw7ZC8GVhSrMXZtAkmu8rt46H5rWiMNCBytR51VkF+RpOqkU D8YAKplrqyscw== Message-ID: Date: Wed, 6 Sep 2023 22:55:28 +0300 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 9/9] ASoC: cs35l41: Use devm_pm_runtime_enable() Content-Language: en-US To: Charles Keepax Cc: James Schulman , David Rhodes , Richard Fitzgerald , Jaroslav Kysela , Takashi Iwai , Liam Girdwood , Mark Brown , Stefan Binding , alsa-devel@alsa-project.org, patches@opensource.cirrus.com, linux-kernel@vger.kernel.org, kernel@collabora.com References: <20230902210621.1184693-1-cristian.ciocaltea@collabora.com> <20230902210621.1184693-10-cristian.ciocaltea@collabora.com> <20230905094535.GK103419@ediswmail.ad.cirrus.com> <953eb242-4d52-4cdc-8f7d-71af003778c5@collabora.com> <20230906163725.GN103419@ediswmail.ad.cirrus.com> From: Cristian Ciocaltea In-Reply-To: <20230906163725.GN103419@ediswmail.ad.cirrus.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/6/23 19:37, Charles Keepax wrote: > On Tue, Sep 05, 2023 at 10:15:46PM +0300, Cristian Ciocaltea wrote: >> On 9/5/23 12:45, Charles Keepax wrote: >>> On Sun, Sep 03, 2023 at 12:06:21AM +0300, Cristian Ciocaltea wrote: >>>> Simplify runtime PM during probe by converting pm_runtime_enable() to >>>> the managed version. >>>> >>>> Signed-off-by: Cristian Ciocaltea >>>> --- >>>> @@ -1376,7 +1379,6 @@ void cs35l41_remove(struct cs35l41_private *cs35l41) >>>> cancel_work_sync(&cs35l41->mdsync_up_work); >>>> >>>> pm_runtime_get_sync(cs35l41->dev); >>>> - pm_runtime_disable(cs35l41->dev); >>>> >>>> regmap_write(cs35l41->regmap, CS35L41_IRQ1_MASK1, 0xFFFFFFFF); >>>> if (cs35l41->hw_cfg.bst_type == CS35L41_SHD_BOOST_PASS || >>> >>> Are we sure this is safe? The remove handler appears to be >>> written to disable pm_runtime at the start presumably to stop the >>> resume/suspend handler running during the remove callback. >>> Whereas after this change the pm_runtime isn't disabled until >>> after the remove callback has run. Does this open a window were >>> we could get an erroneous pm_runtime suspend after the >>> pm_runtime_put_noidle? >> >> I've just made a test adding a 6s sleep before returning from the remove >> handler: >> >> [14444.894316] cs35l41 spi-VLV1776:00: Runtime resume >> [14444.894469] cs35l41 spi-VLV1776:00: sleep 6s before return of cs35l41_remove() >> [14448.338994] cs35l41 spi-VLV1776:00: Runtime suspend >> [14451.079649] cs35l41 spi-VLV1776:00: return from cs35l41_remove() >> [14451.080129] cs35l41 spi-VLV1776:00: Runtime resume >> [14451.080165] cs35l41 spi-VLV1776:00: ASoC: Unregistered DAI 'cs35l41-pcm' >> [14451.080181] cs35l41 spi-VLV1776:00: Runtime suspend >> [14451.813639] acp5x_i2s_playcap acp5x_i2s_playcap.0: ASoC: Unregistered DAI 'acp5x_i2s_playcap.0' >> >> As expected, suspend triggered, but a resume was issued later, before DAI >> got unregistered. >> >> I didn't notice any issues while repeating the test several times, hence >> I wonder what would be the reason to prevent getting suspend/resume events >> at this point? > > The enter/exit hibernate code might run, which at the very > least might result in a bunch of unexpected and failing bus > traffic. Having a bit of a poke through the code, I guess the > most dangerous thing would if you actually got as far as an > extra runtime resume. This might cause cs35l41_init_boost > to run which would undo the work done by the call to > cs35l41_safe_reset in remove, which could leave the boost in a > dangerous state when we enable reset/power down the supplies, > which I think was not considered good. But its just likely > simpler/cleaner if we don't have to think about all the > possible implications of such things by just not allowing > it to happen. Agree, let's keep it simple. I will revert the change and instead ensure a proper cleanup of pm_runtime_use_autosuspend(), according to the documentation: "It's important to undo this with pm_runtime_dont_use_autosuspend() at driver exit time unless your driver initially enabled pm_runtime with devm_pm_runtime_enable() (which handles it for you)." Thanks for the clarifications, Cristian