[PATCH 3/5] bus: mhi: host: pci_generic: Read SUBSYSTEM_VENDOR_ID for VF's to check status

[Vivek . Pernamitta]

From: Vivek Pernamitta <quic_vpernami@xxxxxxxxxxx>

In SRIOV enabled devices, the VF DEVICE/VENDOR ID register returns FFFFh
when read (PCIe SRIOV spec-3.4.1.1). Therefore, read the PCIe
SUBSYSTEM_VENDOR_ID to check if the device is active.

Signed-off-by: Vivek Pernamitta <quic_vpernami@xxxxxxxxxxx>
---
 drivers/bus/mhi/host/pci_generic.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/bus/mhi/host/pci_generic.c b/drivers/bus/mhi/host/pci_generic.c
index 22de02c26ceb946fb618d962ac8882d2db1be6b4..938f37d306a18b9a47f302df85697f837c225f0d 100644
--- a/drivers/bus/mhi/host/pci_generic.c
+++ b/drivers/bus/mhi/host/pci_generic.c
@@ -1025,8 +1025,10 @@ static bool mhi_pci_is_alive(struct mhi_controller *mhi_cntrl)
 	struct pci_dev *pdev = to_pci_dev(mhi_cntrl->cntrl_dev);
 	u16 vendor = 0;
 
-	if (pci_read_config_word(pdev, PCI_VENDOR_ID, &vendor))
-		return false;
+	if (pdev->is_virtfn)
+		pci_read_config_word(pdev, PCI_SUBSYSTEM_VENDOR_ID, &vendor);
+	else
+		pci_read_config_word(pdev, PCI_VENDOR_ID, &vendor);
 
 	if (vendor == (u16) ~0 || vendor == 0)
 		return false;

-- 
2.34.1