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=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 DE75EC48BE0 for ; Fri, 11 Jun 2021 16:29:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0AE260D07 for ; Fri, 11 Jun 2021 16:29:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230269AbhFKQbc (ORCPT ); Fri, 11 Jun 2021 12:31:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230136AbhFKQb3 (ORCPT ); Fri, 11 Jun 2021 12:31:29 -0400 Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69023C0617AF for ; Fri, 11 Jun 2021 09:29:21 -0700 (PDT) Received: by mail-pf1-x42e.google.com with SMTP id g6so4873655pfq.1 for ; Fri, 11 Jun 2021 09:29:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=3/eX1BStPq88A20kAipbkOk3FyPBK6b1OqKfu9OBG6c=; b=bTooVZOlg62B2ZAud90QJFaBxQJg/uZ84EYm3uA41eVAhrt6rYG7MZwyl1knxXgE3R oeoBy32MujQJbLnnA/u6tcqnfz2MLAdi0IaeWUegcgZk6Q8kzUD+BSoGdYXADeoq6/Zf XVS9gcUvC6pTfnr3KYOMaIApGjXaCEzUuKLwk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=3/eX1BStPq88A20kAipbkOk3FyPBK6b1OqKfu9OBG6c=; b=ITE9ws4IuhEiIxJEX0irxAzCv9i58/JLp9qJCvf0WlxXErbHFFI6IFyTLaU5YStrjX lUsbn9RULVqdUp4Ojfa3oGoenEWuB6frFhkjwTkCksxym2sbjyiuJBuzhSpc32LB4KxP llHvnP5McjgxPs+A32Hy4s43cWKkItv7u6OmrnCAgZFk+5FV4EV6dG9OHWb9UouD8Yqg 82cmObiREdDzPAHfOI0sJKxNwu7QIptuMdRsewHwP0JCayiX89jdf7ILrHzCaCNc9riy lyjcqfdBNUkbS38CWPftTxqYRmAQHltk6PLMmqxDxGuuz7YyauzmOWIwMwgaqJRJQdeC +UyA== X-Gm-Message-State: AOAM533zhdcOamjnMAqoPTXqlllEmXMvvYQuq9OA9Pd6JUCgnNY3c90z qiJSDLJUehidELvvjTahF3F/r9dUJus92g== X-Google-Smtp-Source: ABdhPJyb+ZUJ3oRp5zDcqDz4AAar8QPY8s6eKp6yvD+hsI3aoJftwlBSXJWCMSG4bDOXKYlUI5kfmg== X-Received: by 2002:a62:3444:0:b029:2ec:9658:a755 with SMTP id b65-20020a6234440000b02902ec9658a755mr9023721pfa.71.1623428958419; Fri, 11 Jun 2021 09:29:18 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:201:4128:5428:5cd0:cfa5]) by smtp.gmail.com with ESMTPSA id m129sm5804006pfb.7.2021.06.11.09.29.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Jun 2021 09:29:17 -0700 (PDT) From: Douglas Anderson To: Jiri Kosina , Benjamin Tissoires Cc: Douglas Anderson , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] HID: i2c-hid: goodix: Tie the reset line to true state of the regulator Date: Fri, 11 Jun 2021 09:28:56 -0700 Message-Id: <20210611092847.1.I358cae5e33f742765fd38485d6ddf1a4a978644d@changeid> X-Mailer: git-send-email 2.32.0.272.g935e593368-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The regulator for the touchscreen could be: * A dedicated regulator just for the touchscreen. * A regulator shared with something else in the system. * An always-on regulator. How we want the "reset" line to behave depends a bit on which of those three cases we're in. Currently the code is written with the assumption that it has a dedicated regulator, but that's not really guaranteed to be the case. The problem we run into is that if we leave the touchscreen powered on (because someone else is requesting the regulator or it's an always-on regulator) and we assert reset then we apparently burn an extra 67 mW of power. That's not great. Let's instead tie the control of the reset line to the true state of the regulator as reported by regulator notifiers. If we have an always-on regulator our notifier will never be called. If we have a shared regulator then our notifier will be called when the touchscreen is truly turned on or truly turned off. Using notifiers like this nicely handles all the cases without resorting to hacks like pretending that there is no "reset" GPIO if we have an always-on regulator. NOTE: if the regulator is on a shared line it's still possible that things could be a little off. Specifically, this case is not handled even after this patch: 1. Suspend goodix (send "sleep", goodix stops requesting regulator on) 2. Other regulator user turns off (regulator fully turns off). 3. Goodix driver gets notified and asserts reset. 4. Other regulator user turns on. 5. Goodix driver gets notified and deasserts reset. 6. Nobody resumes goodix. With that set of steps we'll have reset deasserted but we will have lost the results of the I2C_HID_PWR_SLEEP from the suspend path. That means we might be in higher power than we could be even if the goodix driver thinks things are suspended. Presumably, however, we're still in better shape than if we were asserting "reset" the whole time. If somehow the above situation is actually affecting someone and we want to do better we can deal with it when we have a real use case. Signed-off-by: Douglas Anderson --- drivers/hid/i2c-hid/i2c-hid-of-goodix.c | 90 +++++++++++++++++++++---- 1 file changed, 77 insertions(+), 13 deletions(-) diff --git a/drivers/hid/i2c-hid/i2c-hid-of-goodix.c b/drivers/hid/i2c-hid/i2c-hid-of-goodix.c index ee0225982a82..c13ea29c7911 100644 --- a/drivers/hid/i2c-hid/i2c-hid-of-goodix.c +++ b/drivers/hid/i2c-hid/i2c-hid-of-goodix.c @@ -26,28 +26,29 @@ struct i2c_hid_of_goodix { struct i2chid_ops ops; struct regulator *vdd; + struct notifier_block nb; + struct mutex regulator_mutex; struct gpio_desc *reset_gpio; const struct goodix_i2c_hid_timing_data *timings; }; -static int goodix_i2c_hid_power_up(struct i2chid_ops *ops) +static void goodix_i2c_hid_deassert_reset(struct i2c_hid_of_goodix *ihid_goodix, + bool regulator_just_turned_on) { - struct i2c_hid_of_goodix *ihid_goodix = - container_of(ops, struct i2c_hid_of_goodix, ops); - int ret; - - ret = regulator_enable(ihid_goodix->vdd); - if (ret) - return ret; - - if (ihid_goodix->timings->post_power_delay_ms) + if (regulator_just_turned_on && ihid_goodix->timings->post_power_delay_ms) msleep(ihid_goodix->timings->post_power_delay_ms); gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 0); if (ihid_goodix->timings->post_gpio_reset_delay_ms) msleep(ihid_goodix->timings->post_gpio_reset_delay_ms); +} - return 0; +static int goodix_i2c_hid_power_up(struct i2chid_ops *ops) +{ + struct i2c_hid_of_goodix *ihid_goodix = + container_of(ops, struct i2c_hid_of_goodix, ops); + + return regulator_enable(ihid_goodix->vdd); } static void goodix_i2c_hid_power_down(struct i2chid_ops *ops) @@ -55,20 +56,54 @@ static void goodix_i2c_hid_power_down(struct i2chid_ops *ops) struct i2c_hid_of_goodix *ihid_goodix = container_of(ops, struct i2c_hid_of_goodix, ops); - gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1); regulator_disable(ihid_goodix->vdd); } +static int ihid_goodix_vdd_notify(struct notifier_block *nb, + unsigned long event, + void *ignored) +{ + struct i2c_hid_of_goodix *ihid_goodix = + container_of(nb, struct i2c_hid_of_goodix, nb); + int ret = NOTIFY_OK; + + mutex_lock(&ihid_goodix->regulator_mutex); + + switch (event) { + case REGULATOR_EVENT_PRE_DISABLE: + gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1); + break; + + case REGULATOR_EVENT_ENABLE: + goodix_i2c_hid_deassert_reset(ihid_goodix, true); + break; + + case REGULATOR_EVENT_ABORT_DISABLE: + goodix_i2c_hid_deassert_reset(ihid_goodix, false); + break; + + default: + ret = NOTIFY_DONE; + break; + } + + mutex_unlock(&ihid_goodix->regulator_mutex); + + return ret; +} + static int i2c_hid_of_goodix_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct i2c_hid_of_goodix *ihid_goodix; - + int ret; ihid_goodix = devm_kzalloc(&client->dev, sizeof(*ihid_goodix), GFP_KERNEL); if (!ihid_goodix) return -ENOMEM; + mutex_init(&ihid_goodix->regulator_mutex); + ihid_goodix->ops.power_up = goodix_i2c_hid_power_up; ihid_goodix->ops.power_down = goodix_i2c_hid_power_down; @@ -84,6 +119,35 @@ static int i2c_hid_of_goodix_probe(struct i2c_client *client, ihid_goodix->timings = device_get_match_data(&client->dev); + /* + * We need to control the "reset" line in lockstep with the regulator + * actually turning on an off instead of just when we make the request. + * This matters if the regulator is shared with another consumer. + * - If the regulator is off then we must assert reset. The reset + * line is active low and on some boards it could cause a current + * leak if left high. + * - If the regulator is on then we don't want reset asserted for very + * long. Holding the controller in reset apparently draws extra + * power. + */ + mutex_lock(&ihid_goodix->regulator_mutex); + ihid_goodix->nb.notifier_call = ihid_goodix_vdd_notify; + ret = regulator_register_notifier(ihid_goodix->vdd, &ihid_goodix->nb); + if (ret) + return dev_err_probe(&client->dev, ret, + "regulator notifier request failed\n"); + + /* + * If someone else is holding the regulator on (or the regulator is + * an always-on one) we might never be told to deassert reset. Do it + * now. Here we'll assume that someone else might have _just + * barely_ turned the regulator on so we'll do the full + * "post_power_delay" just in case. + */ + if (ihid_goodix->reset_gpio && regulator_is_enabled(ihid_goodix->vdd)) + goodix_i2c_hid_deassert_reset(ihid_goodix, true); + mutex_unlock(&ihid_goodix->regulator_mutex); + return i2c_hid_core_probe(client, &ihid_goodix->ops, 0x0001); } -- 2.32.0.272.g935e593368-goog