linux-kernel - Re: [PATCH v5 2/5] PCI: Check PCI_PM_CTRL instead of PCI_COMMAND in pci_dev

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Message-ID: <20240913072356.GO275077@black.fi.intel.com>
Date: Fri, 13 Sep 2024 10:23:56 +0300
From: Mika Westerberg <mika.westerberg@...ux.intel.com>
To: Mario Limonciello <mario.limonciello@....com>
Cc: Bjorn Helgaas <helgaas@...nel.org>, Gary Li <Gary.Li@....com>,
	Mario Limonciello <superm1@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Mathias Nyman <mathias.nyman@...el.com>,
	"open list : PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>,
	"open list : USB XHCI DRIVER" <linux-usb@...r.kernel.org>,
	Daniel Drake <drake@...lessos.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: Re: [PATCH v5 2/5] PCI: Check PCI_PM_CTRL instead of PCI_COMMAND in
 pci_dev_wait()

Hi again,

On Fri, Sep 13, 2024 at 07:58:07AM +0300, Mika Westerberg wrote:
> Yeah, I agree now. It does not look like the methods are messing each
> other here. We don't see the GPE handler being run but I don't think it
> matters here. For some reason the device just is not yet ready when it
> is supposed to be in D0.
> 
> Sorry for wasting your time with these suspects.

One more suggestion though ;-) I realized that my hack patch to disable
I/O and MMIO did not actually do that because it looks like we don't
clear those bits ever. I wonder if you could still check if the below
changes anything? At least it should now "disable" the device to follow
the spec.

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index f412ef73a6e4..79a566376301 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -1332,6 +1332,7 @@ static int pci_pm_runtime_suspend(struct device *dev)
 
 	if (!pci_dev->state_saved) {
 		pci_save_state(pci_dev);
+		pci_pm_default_suspend(pci_dev);
 		pci_finish_runtime_suspend(pci_dev);
 	}
 
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ffaaca0978cb..91f4e7a03c94 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2218,6 +2218,13 @@ static void do_pci_disable_device(struct pci_dev *dev)
 		pci_command &= ~PCI_COMMAND_MASTER;
 		pci_write_config_word(dev, PCI_COMMAND, pci_command);
 	}
+	/*
+	 * PCI PM 1.2 sec 8.2.2 says that when a function is put into D3
+	 * the OS needs to disable I/O and MMIO space in addition to bus
+	 * mastering so do that here.
+	 */
+	pci_command &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY);
+	pci_write_config_word(dev, PCI_COMMAND, pci_command);
 
 	pcibios_disable_device(dev);
 }