[PATCH v2 1/2] PCI: PM: Avoid resuming devices in D3hot during system suspend

From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PCI <linux-pci@vger.kernel.org>
Cc: Linux PM <linux-pm@vger.kernel.org>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH v2 1/2] PCI: PM: Avoid resuming devices in D3hot during system suspend
Date: Fri, 07 Jun 2019 00:30:58 +0200	[thread overview]
Message-ID: <3078848.tiz3m2NLmW@kreacher> (raw)
In-Reply-To: <2958812.87Qy2A3tJo@kreacher>

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

The current code resumes devices in D3hot during system suspend if
the target power state for them is D3cold, but that is not necessary
in general.  It only is necessary to do that if the platform firmware
requires the device to be resumed, but that should be covered by
the platform_pci_need_resume() check anyway, so rework
pci_dev_keep_suspended() to avoid returning 'false' for devices
in D3hot which need not be resumed due to platform firmware
requirements.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

-> v2: Add an empty line as requested during review.

---
 drivers/pci/pci.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

Index: linux-pm/drivers/pci/pci.c
===================================================================

--- linux-pm.orig/drivers/pci/pci.c
+++ linux-pm/drivers/pci/pci.c
@@ -2474,10 +2474,20 @@ bool pci_dev_keep_suspended(struct pci_d
 {
 	struct device *dev = &pci_dev->dev;
 	bool wakeup = device_may_wakeup(dev);
+	pci_power_t target_state;
 
-	if (!pm_runtime_suspended(dev)
-	    || pci_target_state(pci_dev, wakeup) != pci_dev->current_state
-	    || platform_pci_need_resume(pci_dev))
+	if (!pm_runtime_suspended(dev) || platform_pci_need_resume(pci_dev))
+		return false;
+
+	target_state = pci_target_state(pci_dev, wakeup);
+
+	/*
+	 * If the earlier platform check has not triggered, D3cold is just power
+	 * removal on top of D3hot, so no need to resume the device in that
+	 * case.
+	 */
+	if (target_state != pci_dev->current_state &&
+	    target_state != PCI_D3cold && pci_dev->current_state != PCI_D3hot)
 		return false;
 
 	/*



