Merge tag 'pci-v4.19-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaa...

[linux-2.6-microblaze.git] / drivers / pci / pci-acpi.c

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 5100fd2..738e354 100644 (file)
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -612,6 +612,18 @@ static bool acpi_pci_need_resume(struct pci_dev *dev)
 {
        struct acpi_device *adev = ACPI_COMPANION(&dev->dev);
 
+       /*
+        * In some cases (eg. Samsung 305V4A) leaving a bridge in suspend over
+        * system-wide suspend/resume confuses the platform firmware, so avoid
+        * doing that, unless the bridge has a driver that should take care of
+        * the PM handling.  According to Section 16.1.6 of ACPI 6.2, endpoint
+        * devices are expected to be in D3 before invoking the S3 entry path
+        * from the firmware, so they should not be affected by this issue.
+        */
+       if (pci_is_bridge(dev) && !dev->driver &&
+           acpi_target_system_state() != ACPI_STATE_S0)
+               return true;
+
        if (!adev || !acpi_device_power_manageable(adev))
                return false;