PCI: Support Immediate Readiness on devices without PM capabilities

JIRA: https://issues.redhat.com/browse/RHEL-107898
Upstream Status: 5c0d0ee

Conflict(s):
  Patching file drivers/pci/pci.c; Hunk #2 FAILED at 3265.
  Context fuzz due to upstream patch not taking into account a prior
  commit (907a7a2 "PCI/PM: Set up runtime PM even for devices
  without PCI PM").


commit 5c0d0ee
Author: Sean Christopherson <seanjc@google.com>
Date:   Tue Jul 22 08:59:26 2025 -0700

    PCI: Support Immediate Readiness on devices without PM capabilities

    Query support for Immediate Readiness irrespective of whether or not the
    device supports PM capabilities, as nothing in the PCIe spec suggests that
    Immediate Readiness is in any way dependent on PM functionality.

    Fixes: d6112f8 ("PCI: Add support for Immediate Readiness")
    Signed-off-by: Sean Christopherson <seanjc@google.com>
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
    Cc: David Matlack <dmatlack@google.com>
    Cc: Vipin Sharma <vipinsh@google.com>
    Cc: Aaron Lewis <aaronlewis@google.com>
    Link: https://patch.msgid.link/20250722155926.352248-1-seanjc@google.com

Signed-off-by: Myron Stowe <mstowe@redhat.com>

Author: Myron Stowe

drivers/pci/pci.c

@@ -3205,7 +3205,6 @@ void pci_pm_power_up_and_verify_state(struct pci_dev *pci_dev)
 void pci_pm_init(struct pci_dev *dev)
 {
 	int pm;
-	u16 status;
 	u16 pmc;
 
 	device_enable_async_suspend(&dev->dev);
@@ -3266,9 +3265,6 @@ void pci_pm_init(struct pci_dev *dev)
 		pci_pme_active(dev, false);
 	}
 
-	pci_read_config_word(dev, PCI_STATUS, &status);
-	if (status & PCI_STATUS_IMM_READY)
-		dev->imm_ready = 1;
 poweron:
 	pci_pm_power_up_and_verify_state(dev);
 	pm_runtime_forbid(&dev->dev);

drivers/pci/probe.c

@@ -2554,6 +2554,15 @@ void pcie_report_downtraining(struct pci_dev *dev)
 	__pcie_print_link_status(dev, false);
 }
 
+static void pci_imm_ready_init(struct pci_dev *dev)
+{
+	u16 status;
+
+	pci_read_config_word(dev, PCI_STATUS, &status);
+	if (status & PCI_STATUS_IMM_READY)
+		dev->imm_ready = 1;
+}
+
 static void pci_init_capabilities(struct pci_dev *dev)
 {
 	pci_ea_init(dev);		/* Enhanced Allocation */
@@ -2563,6 +2572,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
 	/* Buffers for saving PCIe and PCI-X capabilities */
 	pci_allocate_cap_save_buffers(dev);
 
+	pci_imm_ready_init(dev);	/* Immediate Readiness */
 	pci_pm_init(dev);		/* Power Management */
 	pci_vpd_init(dev);		/* Vital Product Data */
 	pci_configure_ari(dev);		/* Alternative Routing-ID Forwarding */