From nobody Tue Feb 10 08:03:20 2026 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 90A27C04A6A for ; Thu, 27 Jul 2023 17:19:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232851AbjG0RT5 (ORCPT ); Thu, 27 Jul 2023 13:19:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232996AbjG0RTV (ORCPT ); Thu, 27 Jul 2023 13:19:21 -0400 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82FB53C31 for ; Thu, 27 Jul 2023 10:18:54 -0700 (PDT) Received: by mail-pf1-x429.google.com with SMTP id d2e1a72fcca58-686be3cbea0so1576231b3a.0 for ; Thu, 27 Jul 2023 10:18:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1690478333; x=1691083133; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=oQ1jk/KOTlP01sIFni7CwDm+I437xIRRpg2DbYMJz0w=; b=aAswUTeKFFukfWQJx4v7uNalIbnFpfwWYhVmE+KGA04UV5rjshOUja9o6SMWNzn/WG xt5tAr4aVqPTnzu+ScC6lFGwkbYXq07byVeGdfgjq5whQyVo7TppEx0AIiuMr/LNN/lr ExFuTKo34K51MTFeVz3TwHBDvJJOp/wgjqxho= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690478333; x=1691083133; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=oQ1jk/KOTlP01sIFni7CwDm+I437xIRRpg2DbYMJz0w=; b=LjxxsKOiZ+Dsm++z5ORR/EFAPyEfbI+ZaCPMqnXW4RBCoIp9jZFnlwMLjt3591T6wo arxg+wu9jxjk0IbjcXjr9uZQtatV4ohOB02LO9G7tG4Omct3S0v7f2ns2joBywS+PbYl 7UpeMBgj7AbtXFx/6QnBufHUi186ehgLWEVcCTWKurrnCDsrefX5w2jsn3X+ihGnNL+/ cUz3wNjmq/dZtXZbjrpU7bALVpAFCwjlVD/du2ybpDvkHwiXUBVx1CPUIBPrNFvqlYGK NjZC6K7npgrq5BsSg8DA31GePMQfAlL/NYomWasYeC7NxlKHX1RbEPMSrjuqtVyPYH37 taAg== X-Gm-Message-State: ABy/qLYnFyaHNJf4wgbhrRB3su+MuZT3QzD34BQ6/O1IW8JHJ5D4/mdr 2/vsmF2Jj10HwxXCh9Je0uOsEQ== X-Google-Smtp-Source: APBJJlFoDfQb+6/rj0nXnjfpM4aIPCqGSEFrI23kykKq4DzWXZqpYTvtPVU5dUZSdSKTjXpKGEFQAg== X-Received: by 2002:a05:6a20:3d02:b0:132:c1fd:aaab with SMTP id y2-20020a056a203d0200b00132c1fdaaabmr4137849pzi.30.1690478333644; Thu, 27 Jul 2023 10:18:53 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:9d:2:2339:954b:b98f:611a]) by smtp.gmail.com with ESMTPSA id 17-20020aa79111000000b0064f76992905sm1702524pfh.202.2023.07.27.10.18.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Jul 2023 10:18:53 -0700 (PDT) From: Douglas Anderson To: Jiri Kosina , Benjamin Tissoires , Bjorn Andersson , Konrad Dybcio , Rob Herring , Frank Rowand , Krzysztof Kozlowski , Conor Dooley , Neil Armstrong , Sam Ravnborg , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann Cc: linux-arm-msm@vger.kernel.org, yangcong5@huaqin.corp-partner.google.com, devicetree@vger.kernel.org, Daniel Vetter , hsinyi@google.com, Chris Morgan , linux-input@vger.kernel.org, cros-qcom-dts-watchers@chromium.org, Dmitry Torokhov , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Douglas Anderson Subject: [PATCH v4 10/11] HID: i2c-hid: Do panel follower work on the system_wq Date: Thu, 27 Jul 2023 10:16:37 -0700 Message-ID: <20230727101636.v4.10.I962bb462ede779005341c49320740ed95810021d@changeid> X-Mailer: git-send-email 2.41.0.487.g6d72f3e995-goog In-Reply-To: <20230727171750.633410-1-dianders@chromium.org> References: <20230727171750.633410-1-dianders@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Turning on an i2c-hid device can be a slow process. This is why i2c-hid devices use PROBE_PREFER_ASYNCHRONOUS. Unfortunately, when we're a panel follower the i2c-hid power up sequence now blocks the power on of the panel. Let's fix that by scheduling the work on the system_wq. Reviewed-by: Maxime Ripard Signed-off-by: Douglas Anderson --- (no changes since v2) Changes in v2: - ihid_core_panel_prepare_work() is now static. - Improve documentation for smp_wmb(). drivers/hid/i2c-hid/i2c-hid-core.c | 50 +++++++++++++++++++++++++++--- 1 file changed, 46 insertions(+), 4 deletions(-) diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-h= id-core.c index fc3087a983f5..9601c0605fd9 100644 --- a/drivers/hid/i2c-hid/i2c-hid-core.c +++ b/drivers/hid/i2c-hid/i2c-hid-core.c @@ -110,7 +110,9 @@ struct i2c_hid { =20 struct i2chid_ops *ops; struct drm_panel_follower panel_follower; + struct work_struct panel_follower_prepare_work; bool is_panel_follower; + bool prepare_work_finished; }; =20 static const struct i2c_hid_quirks { @@ -1062,10 +1064,12 @@ static int __do_i2c_hid_core_initial_power_up(struc= t i2c_hid *ihid) return ret; } =20 -static int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower) +static void ihid_core_panel_prepare_work(struct work_struct *work) { - struct i2c_hid *ihid =3D container_of(follower, struct i2c_hid, panel_fol= lower); + struct i2c_hid *ihid =3D container_of(work, struct i2c_hid, + panel_follower_prepare_work); struct hid_device *hid =3D ihid->hid; + int ret; =20 /* * hid->version is set on the first power up. If it's still zero then @@ -1073,15 +1077,52 @@ static int i2c_hid_core_panel_prepared(struct drm_p= anel_follower *follower) * steps. */ if (!hid->version) - return __do_i2c_hid_core_initial_power_up(ihid); + ret =3D __do_i2c_hid_core_initial_power_up(ihid); + else + ret =3D i2c_hid_core_resume(ihid); =20 - return i2c_hid_core_resume(ihid); + if (ret) + dev_warn(&ihid->client->dev, "Power on failed: %d\n", ret); + else + WRITE_ONCE(ihid->prepare_work_finished, true); + + /* + * The work APIs provide a number of memory ordering guarantees + * including one that says that memory writes before schedule_work() + * are always visible to the work function, but they don't appear to + * guarantee that a write that happened in the work is visible after + * cancel_work_sync(). We'll add a write memory barrier here to match + * with i2c_hid_core_panel_unpreparing() to ensure that our write to + * prepare_work_finished is visible there. + */ + smp_wmb(); +} + +static int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower) +{ + struct i2c_hid *ihid =3D container_of(follower, struct i2c_hid, panel_fol= lower); + + /* + * Powering on a touchscreen can be a slow process. Queue the work to + * the system workqueue so we don't block the panel's power up. + */ + WRITE_ONCE(ihid->prepare_work_finished, false); + schedule_work(&ihid->panel_follower_prepare_work); + + return 0; } =20 static int i2c_hid_core_panel_unpreparing(struct drm_panel_follower *follo= wer) { struct i2c_hid *ihid =3D container_of(follower, struct i2c_hid, panel_fol= lower); =20 + cancel_work_sync(&ihid->panel_follower_prepare_work); + + /* Match with ihid_core_panel_prepare_work() */ + smp_rmb(); + if (!READ_ONCE(ihid->prepare_work_finished)) + return 0; + return i2c_hid_core_suspend(ihid, true); } =20 @@ -1173,6 +1214,7 @@ int i2c_hid_core_probe(struct i2c_client *client, str= uct i2chid_ops *ops, =20 init_waitqueue_head(&ihid->wait); mutex_init(&ihid->reset_lock); + INIT_WORK(&ihid->panel_follower_prepare_work, ihid_core_panel_prepare_wor= k); =20 /* we need to allocate the command buffer without knowing the maximum * size of the reports. Let's use HID_MIN_BUFFER_SIZE, then we do the --=20 2.41.0.487.g6d72f3e995-goog