PCI: Leave Apple Thunderbolt controllers on for s2idle or standby

On Macbook 2013, resuming from suspend-to-idle or standby resulted in the
external monitor no longer being detected, a stacktrace, and errors like
this in dmesg:

  pcieport 0000:06:00.0: can't change power state from D3hot to D0 (config space inaccessible)

The reason is that we know how to turn power to the Thunderbolt controller
*off* via the SXIO/SXFP/SXLF methods, but we don't know how to turn power
back on.  We have to rely on firmware to turn the power back on.

When going to the "suspend-to-idle" or "standby" system sleep states,
firmware is not involved either on the suspend side or the resume side, so
we can't use SXIO/SXFP/SXLF to turn the power off.

Skip SXIO/SXFP/SXLF when firmware isn't involved in suspend, e.g., when
we're going to the "suspend-to-idle" or "standby" system sleep states.

Fixes: 1df5172 ("PCI: Suspend/resume quirks for Apple thunderbolt")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212767
Link: https://lore.kernel.org/r/20210520235501.917397-1-Hi-Angel@yandex.ru
Signed-off-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org

drivers/pci/quirks.c

@@ -27,6 +27,7 @@
 #include <linux/nvme.h>
 #include <linux/platform_data/x86/apple.h>
 #include <linux/pm_runtime.h>
+#include <linux/suspend.h>
 #include <linux/switchtec.h>
 #include <asm/dma.h>	/* isa_dma_bridge_buggy */
 #include "pci.h"
@@ -3634,6 +3635,16 @@ static void quirk_apple_poweroff_thunderbolt(struct pci_dev *dev)
 		return;
 	if (pci_pcie_type(dev) != PCI_EXP_TYPE_UPSTREAM)
 		return;
+
+	/*
+	 * SXIO/SXFP/SXLF turns off power to the Thunderbolt controller.
+	 * We don't know how to turn it back on again, but firmware does,
+	 * so we can only use SXIO/SXFP/SXLF if we're suspending via
+	 * firmware.
+	 */
+	if (!pm_suspend_via_firmware())
+		return;
+
 	bridge = ACPI_HANDLE(&dev->dev);
 	if (!bridge)
 		return;