[PATCH v2] PCI: don't call firmware hooks on suspend unless it's fw-controlled

[Konstantin Kharlamov <Hi-Angel@yandex.ru>]

On Macbook 2013 resuming from s2idle resulted in external monitor no
longer being detected, and dmesg having errors like:

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

and a stacktrace. The reason is that in s2idle (and in S1 as noted by
Rafael) we do not call firmware code to handle suspend, and as result
while waking up firmware also does not handle resume.

This means, for the Thunderbolt controller that gets disabled in the
quirk by calling the firmware methods, there's no one to wake it back up
on resume.

To quote Rafael Wysocki:

> "Passing control to the platform firmware" means letting
> some native firmware code (like SMM code) run which happens at the end
> of S2/S3/S4 suspend transitions and it does not happen during S1
> (standby) and s2idle suspend transitions.
>
> That's why using SXIO/SXFP/SXLF is only valid during S2/S3/S4 suspend
> transitions and it is not valid during s2idle and S1 suspend
> transitions (and yes, S1 is also affected, so s2idle is not special in
> that respect at all).

Thus, return early from the quirk when suspend mode isn't one that calls
firmware.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212767
Signed-off-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
---
 drivers/pci/quirks.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 653660e3ba9e..f86b6388a04a 100644
--- a/drivers/pci/quirks.c
+++ b/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"
@@ -3646,6 +3647,15 @@ 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;
-- 
2.31.1