From patchwork Mon Apr 11 14:31:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 12809224 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 DFF70C433F5 for ; Mon, 11 Apr 2022 14:34:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347319AbiDKOgU (ORCPT ); Mon, 11 Apr 2022 10:36:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347318AbiDKOgS (ORCPT ); Mon, 11 Apr 2022 10:36:18 -0400 Received: from cloudserver094114.home.pl (cloudserver094114.home.pl [79.96.170.134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5679437013; Mon, 11 Apr 2022 07:34:02 -0700 (PDT) Received: from localhost (127.0.0.1) (HELO v370.home.net.pl) by /usr/run/smtp (/usr/run/postfix/private/idea_relay_lmtp) via UNIX with SMTP (IdeaSmtpServer 5.0.0) id 587ee8244673976b; Mon, 11 Apr 2022 16:34:01 +0200 Received: from kreacher.localnet (unknown [213.134.175.113]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by v370.home.net.pl (Postfix) with ESMTPSA id 4E4F766BDED; Mon, 11 Apr 2022 16:34:00 +0200 (CEST) From: "Rafael J. Wysocki" To: Linux PCI Cc: Linux PM , LKML , Bjorn Helgaas , Mika Westerberg Subject: [PATCH v2 8/9] PCI/PM: Avoid redundant current_state update Date: Mon, 11 Apr 2022 16:31:45 +0200 Message-ID: <8938882.CDJkKcVGEf@kreacher> In-Reply-To: <11975904.O9o76ZdvQC@kreacher> References: <4419002.LvFx2qVVIh@kreacher> <11975904.O9o76ZdvQC@kreacher> MIME-Version: 1.0 X-CLIENT-IP: 213.134.175.113 X-CLIENT-HOSTNAME: 213.134.175.113 X-VADE-SPAMSTATE: clean X-VADE-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvvddrudekiedgjeelucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecujffqoffgrffnpdggtffipffknecuuegrihhlohhuthemucduhedtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvffufffkjghfggfgtgesthfuredttddtjeenucfhrhhomhepfdftrghfrggvlhculfdrucghhihsohgtkhhifdcuoehrjhifsehrjhifhihsohgtkhhirdhnvghtqeenucggtffrrghtthgvrhhnpedvjeelgffhiedukedtleekkedvudfggefhgfegjefgueekjeelvefggfdvledutdenucfkphepvddufedrudefgedrudejhedruddufeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpedvudefrddufeegrddujeehrdduudefpdhhvghlohepkhhrvggrtghhvghrrdhlohgtrghlnhgvthdpmhgrihhlfhhrohhmpedftfgrfhgrvghlucflrdcuhgihshhotghkihdfuceorhhjfiesrhhjfiihshhotghkihdrnhgvtheqpdhnsggprhgtphhtthhopeehpdhrtghpthhtoheplhhinhhugidqphgtihesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehlihhnuhigqdhpmhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehhvghlghgrrghssehkvghrnhgvlhdrohhrghdprhgtphhtthhopehm ihhkrgdrfigvshhtvghrsggvrhhgsehlihhnuhigrdhinhhtvghlrdgtohhm X-DCC--Metrics: v370.home.net.pl 1024; Body=5 Fuz1=5 Fuz2=5 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Rafael J. Wysocki Notice that if pci_power_up() returns success early, without updating the given device's PCI_PM_CTRL register, because it has verified that the power state of the device is D0 already at that point, the pci_update_current_state() invocation in pci_pm_default_resume_early() is redundant. Avoid that redundant call by making pci_power_up() return 1 when it has updated the device's PCI_PM_CTRL register and checking its return value in pci_pm_default_resume_early(). Signed-off-by: Rafael J. Wysocki --- New patch in v2. --- drivers/pci/pci-driver.c | 5 +++-- drivers/pci/pci.c | 10 ++++++++-- 2 files changed, 11 insertions(+), 4 deletions(-) Index: linux-pm/drivers/pci/pci-driver.c =================================================================== --- linux-pm.orig/drivers/pci/pci-driver.c +++ linux-pm/drivers/pci/pci-driver.c @@ -553,8 +553,9 @@ static void pci_pm_default_resume(struct static void pci_pm_default_resume_early(struct pci_dev *pci_dev) { - pci_power_up(pci_dev); - pci_update_current_state(pci_dev, PCI_D0); + if (pci_power_up(pci_dev)) + pci_update_current_state(pci_dev, PCI_D0); + pci_restore_state(pci_dev); pci_pme_restore(pci_dev); } Index: linux-pm/drivers/pci/pci.c =================================================================== --- linux-pm.orig/drivers/pci/pci.c +++ linux-pm/drivers/pci/pci.c @@ -1189,6 +1189,12 @@ static int pci_dev_wait(struct pci_dev * /** * pci_power_up - Put the given device into D0 * @dev: PCI device to power up + * + * Use the platform firmware and the PCI_PM_CTRL register to put @dev into D0. + * + * Return 0 if invoking the platform firmware was sufficient to put @dev into D0 + * (and so the PCI_PM_CTRL register was not updated), or 1 if it was necessary to + * update the PCI_PM_CTRL register, or -ENODEV if the device was not accessible. */ int pci_power_up(struct pci_dev *dev) { @@ -1235,7 +1241,7 @@ int pci_power_up(struct pci_dev *dev) udelay(PCI_PM_D2_DELAY); dev->current_state = PCI_D0; - return 0; + return 1; fail: pci_err(dev, "Unable to change power state to D0, device inaccessible\n"); @@ -1273,7 +1279,7 @@ static int pci_set_full_power_state(stru int ret; ret = pci_power_up(dev); - if (ret) + if (ret < 0) return ret; if (!dev->pm_cap)