From: Arnd Bergmann <arnd@arndb.de>

A recent patch caused an unused-function warning in builds with
CONFIG_PM disabled, after the function became marked 'static':

drivers/usb/host/xhci-pci.c:91:13: error: 'xhci_msix_sync_irqs' defined but not used [-Werror=unused-function]
   91 | static void xhci_msix_sync_irqs(struct xhci_hcd *xhci)
      |             ^~~~~~~~~~~~~~~~~~~

This could be solved by adding another #ifdef, but as there is
a trend towards removing CONFIG_PM checks in favor of helper
macros, do the same conversion here and use pm_ptr() to get
either a function pointer or NULL but avoid the warning.

As the hidden functions reference some other symbols, make
sure those are visible at compile time, at the minimal cost of
a few extra bytes for 'struct usb_device'.

Fixes: 9abe15d55dcc ("xhci: Move xhci MSI sync function to to xhci-pci")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/usb/host/xhci-pci.c | 16 +++++-----------
 include/linux/usb.h         |  3 +--
 include/linux/usb/hcd.h     |  2 --
 3 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index a53ecc8ff8c5..bbbb01282038 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -728,7 +728,6 @@ static void xhci_pci_remove(struct pci_dev *dev)
 	usb_hcd_pci_remove(dev);
 }
 
-#ifdef CONFIG_PM
 /*
  * In some Intel xHCI controllers, in order to get D3 working,
  * through a vendor specific SSIC CONFIG register at offset 0x883c,
@@ -927,7 +926,6 @@ static void xhci_pci_shutdown(struct usb_hcd *hcd)
 	if (xhci->quirks & XHCI_SPURIOUS_WAKEUP)
 		pci_set_power_state(pdev, PCI_D3hot);
 }
-#endif /* CONFIG_PM */
 
 /*-------------------------------------------------------------------------*/
 
@@ -970,9 +968,7 @@ static struct pci_driver xhci_pci_driver = {
 
 	.shutdown = 	usb_hcd_pci_shutdown,
 	.driver = {
-#ifdef CONFIG_PM
-		.pm = &usb_hcd_pci_pm_ops,
-#endif
+		.pm = pm_ptr(&usb_hcd_pci_pm_ops),
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 	},
 };
@@ -980,12 +976,10 @@ static struct pci_driver xhci_pci_driver = {
 static int __init xhci_pci_init(void)
 {
 	xhci_init_driver(&xhci_pci_hc_driver, &xhci_pci_overrides);
-#ifdef CONFIG_PM
-	xhci_pci_hc_driver.pci_suspend = xhci_pci_suspend;
-	xhci_pci_hc_driver.pci_resume = xhci_pci_resume;
-	xhci_pci_hc_driver.pci_poweroff_late = xhci_pci_poweroff_late;
-	xhci_pci_hc_driver.shutdown = xhci_pci_shutdown;
-#endif
+	xhci_pci_hc_driver.pci_suspend = pm_ptr(xhci_pci_suspend);
+	xhci_pci_hc_driver.pci_resume = pm_ptr(xhci_pci_resume);
+	xhci_pci_hc_driver.pci_poweroff_late = pm_ptr(xhci_pci_poweroff_late);
+	xhci_pci_hc_driver.shutdown = pm_ptr(xhci_pci_shutdown);
 	xhci_pci_hc_driver.stop = xhci_pci_stop;
 	return pci_register_driver(&xhci_pci_driver);
 }
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 9642ee02d713..d510fabcafa2 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -704,13 +704,12 @@ struct usb_device {
 
 	unsigned long active_duration;
 
-#ifdef CONFIG_PM
 	unsigned long connect_time;
 
 	unsigned do_remote_wakeup:1;
 	unsigned reset_resume:1;
 	unsigned port_is_suspended:1;
-#endif
+
 	struct wusb_dev *wusb_dev;
 	int slot_id;
 	struct usb2_lpm_parameters l1_params;
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index b51c07111729..094c77eaf455 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -488,9 +488,7 @@ extern void usb_hcd_pci_shutdown(struct pci_dev *dev);
 
 extern int usb_hcd_amd_remote_wakeup_quirk(struct pci_dev *dev);
 
-#ifdef CONFIG_PM
 extern const struct dev_pm_ops usb_hcd_pci_pm_ops;
-#endif
 #endif /* CONFIG_USB_PCI */
 
 /* pci-ish (pdev null is ok) buffer alloc/mapping support */
-- 
2.39.2

On 28.3.2023 16.10, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> A recent patch caused an unused-function warning in builds with
> CONFIG_PM disabled, after the function became marked 'static':
> 
> drivers/usb/host/xhci-pci.c:91:13: error: 'xhci_msix_sync_irqs' defined but not used [-Werror=unused-function]
>     91 | static void xhci_msix_sync_irqs(struct xhci_hcd *xhci)
>        |             ^~~~~~~~~~~~~~~~~~~
> 
> This could be solved by adding another #ifdef, but as there is
> a trend towards removing CONFIG_PM checks in favor of helper
> macros, do the same conversion here and use pm_ptr() to get
> either a function pointer or NULL but avoid the warning.
> 
> As the hidden functions reference some other symbols, make
> sure those are visible at compile time, at the minimal cost of
> a few extra bytes for 'struct usb_device'.
> 
> Fixes: 9abe15d55dcc ("xhci: Move xhci MSI sync function to to xhci-pci")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Thanks for this.
Looks like Greg already picked it.

-Mathias