PCI: Add generic quirk for increasing D3hot delay

Separate the D3 delay increase functionality out of quirk_radeon_pm() into
its own function so that it can be shared with other quirks, including the
AMD Ryzen XHCI quirk that will be introduced in a followup commit.

Tweak the function name and message to indicate more clearly that the delay
relates to a D3hot-to-D0 transition.

Link: https://lore.kernel.org/r/20191127053836.31624-1-drake@endlessm.comSigned-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/pci/quirks.c

@@ -1871,16 +1871,21 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	0x2609, quirk_intel_pcie_pm);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	0x260a, quirk_intel_pcie_pm);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	0x260b, quirk_intel_pcie_pm);
 
+static void quirk_d3hot_delay(struct pci_dev *dev, unsigned int delay)
+{
+	if (dev->d3_delay >= delay)
+		return;
+
+	dev->d3_delay = delay;
+	pci_info(dev, "extending delay after power-on from D3hot to %d msec\n",
+		 dev->d3_delay);
+}
+
 static void quirk_radeon_pm(struct pci_dev *dev)
 {
 	if (dev->subsystem_vendor == PCI_VENDOR_ID_APPLE &&
-	    dev->subsystem_device == 0x00e2) {
-		if (dev->d3_delay < 20) {
-			dev->d3_delay = 20;
-			pci_info(dev, "extending delay after power-on from D3 to %d msec\n",
-				 dev->d3_delay);
-		}
-	}
+	    dev->subsystem_device == 0x00e2)
+		quirk_d3hot_delay(dev, 20);
 }
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x6741, quirk_radeon_pm);