From patchwork Fri Jun 15 10:04:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Enric Balletbo i Serra X-Patchwork-Id: 10465961 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 038C8600F4 for ; Fri, 15 Jun 2018 10:05:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E5BE328D4B for ; Fri, 15 Jun 2018 10:05:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DA28528D4E; Fri, 15 Jun 2018 10:05:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C07AF28D4B for ; Fri, 15 Jun 2018 10:05:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936165AbeFOKFC (ORCPT ); Fri, 15 Jun 2018 06:05:02 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:32790 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934900AbeFOKFC (ORCPT ); Fri, 15 Jun 2018 06:05:02 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id 7E32F260BF3 From: Enric Balletbo i Serra To: linux-kernel@vger.kernel.org Cc: kernel@collabora.com, Chanwoo Choi , Kyungmin Park , MyungJoo Ham , linux-pm@vger.kernel.org Subject: [PATCH] PM / devfreq: Fix devfreq_add_device() when drivers are built as modules. Date: Fri, 15 Jun 2018 12:04:52 +0200 Message-Id: <20180615100452.17466-1-enric.balletbo@collabora.com> X-Mailer: git-send-email 2.17.1 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When the devfreq driver and the governor driver are built as modules, the call to devfreq_add_device() fails because the governor driver is not loaded at the time the devfreq driver loads. The devfreq driver has a build dependency on the governor but also should have a runtime dependency. We need to make sure that the governor driver is loaded before the devfreq driver. This patch fixes this bug in devfreq_add_device(). First tries to find the governor, and then, if was not found, it requests the module and tries again. Fixes: 1b5c1be2c88e (PM / devfreq: map devfreq drivers to governor using name) Signed-off-by: Enric Balletbo i Serra --- drivers/devfreq/devfreq.c | 36 +++++++++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index fe2af6aa88fc..1d917f043e30 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -11,6 +11,7 @@ */ #include +#include #include #include #include @@ -648,10 +649,35 @@ struct devfreq *devfreq_add_device(struct device *dev, governor = find_devfreq_governor(devfreq->governor_name); if (IS_ERR(governor)) { - dev_err(dev, "%s: Unable to find governor for the device\n", - __func__); - err = PTR_ERR(governor); - goto err_init; + list_del(&devfreq->node); + mutex_unlock(&devfreq_list_lock); + + /* + * If the governor is not found, then request the module and + * try again. This can happen when both drivers (the governor + * driver and the driver that calls devfreq_add_device) are + * built as modules. + */ + if (!strncmp(devfreq->governor_name, + DEVFREQ_GOV_SIMPLE_ONDEMAND, DEVFREQ_NAME_LEN)) + err = request_module("governor_%s", "simpleondemand"); + else + err = request_module("governor_%s", + devfreq->governor_name); + if (err) + goto err_unregister; + + mutex_lock(&devfreq_list_lock); + list_add(&devfreq->node, &devfreq_list); + + governor = find_devfreq_governor(devfreq->governor_name); + if (IS_ERR(governor)) { + dev_err(dev, + "%s: Unable to find governor for the device\n", + __func__); + err = PTR_ERR(governor); + goto err_init; + } } devfreq->governor = governor; @@ -669,7 +695,7 @@ struct devfreq *devfreq_add_device(struct device *dev, err_init: list_del(&devfreq->node); mutex_unlock(&devfreq_list_lock); - +err_unregister: device_unregister(&devfreq->dev); err_dev: if (devfreq)