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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=ham 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 6D8BAC433E0 for ; Wed, 20 May 2020 03:48:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CBE32081A for ; Wed, 20 May 2020 03:48:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="EaXWLFEV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728703AbgETDsk (ORCPT ); Tue, 19 May 2020 23:48:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40812 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728672AbgETDsg (ORCPT ); Tue, 19 May 2020 23:48:36 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9ECFC061A0E for ; Tue, 19 May 2020 20:48:36 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 137so623689ybf.7 for ; Tue, 19 May 2020 20:48:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=RtCGIdkRhfEUupdY905bazGM3jhQowkSorrvjmz8vY4=; b=EaXWLFEVX2Izu4jZPGIozNqD8fhSsekhJitj201hscnozCML3LPvd6AoyOom9988Xm ByShfho3W/hV5njfHwxv1p6VK8ofS+x6E4v2E5uQ7cYLDcSwxU9Ub06FWJBlpNyT0kbX /UTltFOiak/Hg59PZX/3Fi/hDsP8YnSANH+powHCpix0srvmi9TN7ryUjyude9OPNnV4 fpnhLd3sUyZcxqUK+UtImSMphmAaL5S8cLAQHL7GcGHAUFR0jw4YKQAAtHuUudsx1dPB 71XQKCofQ3nd+oc0tPyDA0xMUTrSXnUqBvd45YoQ/D+AORc4Oq/lUV7Ur3otGDFPjvHz oIsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=RtCGIdkRhfEUupdY905bazGM3jhQowkSorrvjmz8vY4=; b=TAumOBDTZSJ/waiqNkeyZLKK9bdcs1BcG2ObVIh1gfxDqbHJCpqZIayS2igorfCL+M 9rEmcDl1LC5ZuSbI4iNg0AEF/GprS5bPqmrYuOdIggq58O0wLfxfRBmFKri61MFLXbOR iTVUdztVx0FcO0KsvmYnoPM2AI+z/3NAkl6RcwGT82Kp/TNlKp3sV9JymZwHhOVWxVCz lhscKDYMokHUPmjtHe48E1mAtjrH5gboS9ip3l6wGXTpPrydiezC/sUsCLGsuhENPXRn AitoeaPNoLujV/cMicecRe3BcbxFiUL92LJRWBiCVeGP7KRo2GNnI2PR/USXjaxiZ98g uvGQ== X-Gm-Message-State: AOAM533EzJ62SwY2oLbEyTkw82TPfxLHYEC2aOVys4CnB9JGBGAKnWOj DbclDF4P7AN4otAeeRaWy6KjSFZ40XRy4e8= X-Google-Smtp-Source: ABdhPJzGg5gGDp4VD6opG8nzJdT0stLwjyMFyFUyVpXa/nBVTzWomhYRfRuEA96c/0onlLGMkkNS9AJpiguD0qs= X-Received: by 2002:a25:aae9:: with SMTP id t96mr4245302ybi.468.1589946515908; Tue, 19 May 2020 20:48:35 -0700 (PDT) Date: Tue, 19 May 2020 20:48:23 -0700 In-Reply-To: <20200520034824.79049-1-saravanak@google.com> Message-Id: <20200520034824.79049-4-saravanak@google.com> Mime-Version: 1.0 References: <20200520034824.79049-1-saravanak@google.com> X-Mailer: git-send-email 2.26.2.761.g0e0b3e54be-goog Subject: [PATCH v2 3/4] driver core: Add state_synced sysfs file for devices that support it From: Saravana Kannan To: Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: Saravana Kannan , linux-kernel@vger.kernel.org, John Stultz , kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This can be used to check if a device supports sync_state() callbacks and therefore keeps resources left on by the bootloader enabled till all its consumers have probed. This can also be used to check if sync_state() has been called for a device or whether it is still trying to keep resources enabled because they were left enabled by the bootloader and all its consumers haven't probed yet. Signed-off-by: Saravana Kannan --- .../ABI/testing/sysfs-devices-state_synced | 24 +++++++++++++++++++ drivers/base/dd.c | 22 +++++++++++++++++ 2 files changed, 46 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-devices-state_synced diff --git a/Documentation/ABI/testing/sysfs-devices-state_synced b/Documentation/ABI/testing/sysfs-devices-state_synced new file mode 100644 index 000000000000..0c922d7d02fc --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-state_synced @@ -0,0 +1,24 @@ +What: /sys/devices/.../state_synced +Date: May 2020 +Contact: Saravana Kannan +Description: + The /sys/devices/.../state_synced attribute is only present for + devices whose bus types or driver provides the .sync_state() + callback. The number read from it (0 or 1) reflects the value + of the device's 'state_synced' field. A value of 0 means the + .sync_state() callback hasn't been called yet. A value of 1 + means the .sync_state() callback has been called. + + Generally, if a device has sync_state() support and has some of + the resources it provides enabled at the time the kernel starts + (Eg: enabled by hardware reset or bootloader or anything that + run before the kernel starts), then it'll keep those resources + enabled and in a state that's compatible with the state they + were in at the start of the kernel. The device will stop doing + this only when the sync_state() callback has been called -- + which happens only when all its consumer devices are registered + and have probed successfully. Resources that were left disabled + at the time the kernel starts are not affected or limited in + any way by sync_state() callbacks. + + diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 9a1d940342ac..7c04b88daac3 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -463,6 +463,18 @@ static void driver_deferred_probe_add_trigger(struct device *dev, driver_deferred_probe_trigger(); } +static ssize_t state_synced_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + bool val; + + device_lock(dev); + val = dev->state_synced; + device_unlock(dev); + return sprintf(buf, "%u\n", val); +} +static DEVICE_ATTR_RO(state_synced); + static int really_probe(struct device *dev, struct device_driver *drv) { int ret = -EPROBE_DEFER; @@ -536,9 +548,16 @@ static int really_probe(struct device *dev, struct device_driver *drv) goto dev_groups_failed; } + if (dev_has_sync_state(dev) && + device_create_file(dev, &dev_attr_state_synced)) { + dev_err(dev, "state_synced sysfs add failed\n"); + goto dev_sysfs_state_synced_failed; + } + if (test_remove) { test_remove = false; + device_remove_file(dev, &dev_attr_state_synced); device_remove_groups(dev, drv->dev_groups); if (dev->bus->remove) @@ -568,6 +587,8 @@ static int really_probe(struct device *dev, struct device_driver *drv) drv->bus->name, __func__, dev_name(dev), drv->name); goto done; +dev_sysfs_state_synced_failed: + device_remove_groups(dev, drv->dev_groups); dev_groups_failed: if (dev->bus->remove) dev->bus->remove(dev); @@ -1105,6 +1126,7 @@ static void __device_release_driver(struct device *dev, struct device *parent) pm_runtime_put_sync(dev); + device_remove_file(dev, &dev_attr_state_synced); device_remove_groups(dev, drv->dev_groups); if (dev->bus && dev->bus->remove) -- 2.26.2.761.g0e0b3e54be-goog