linux-kernel - [PATCH v1 06/11] PCI/PM: Write 0 to PMCSR in pci_power

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Date:   Thu, 05 May 2022 20:10:43 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PCI <linux-pci@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Anders Roxell <anders.roxell@...aro.org>
Subject: [PATCH v1 06/11] PCI/PM: Write 0 to PMCSR in pci_power_up() in all cases

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Make pci_power_up() write 0 to the device's PCI_PM_CTRL register in
order to put it into D0 regardless of the power state returned by
the previous read from that register which should not matter.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/pci/pci.c |   11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

Index: linux-pm/drivers/pci/pci.c
===================================================================
--- linux-pm.orig/drivers/pci/pci.c
+++ linux-pm/drivers/pci/pci.c
@@ -1230,15 +1230,10 @@ int pci_power_up(struct pci_dev *dev)
 	}
 
 	/*
-	 * If we're (effectively) in D3, force entire word to 0. This doesn't
-	 * affect PME_Status, disables PME_En, and sets PowerState to 0.
+	 * Force the entire word to 0. This doesn't affect PME_Status, disables
+	 * PME_En, and sets PowerState to 0.
 	 */
-	if (state == PCI_D3hot)
-		pmcsr = 0;
-	else
-		pmcsr &= ~PCI_PM_CTRL_STATE_MASK;
-
-	pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, pmcsr);
+	pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, 0);
 
 	/* Mandatory transition delays; see PCI PM 1.2. */
 	if (state == PCI_D3hot)