[PATCH v2] PCI: Disable broken FLR on MediaTek MT7925

[Jose Ignacio Tornos Martinez <jtornosm@redhat.com>]

The MediaTek MT7925 WiFi device (14c3:7925) advertises FLR capability
but the implementation is broken - reset always fails, leaving the device
in an undefined state.

This manifests in VFIO passthrough scenarios: Normal VM operation works
fine, including clean shutdown/reboot. However, when the VM terminates
uncleanly (crash, force-off), VFIO attempts to reset the device before
it can be assigned to another VM. Because FLR is broken, the reset fails
and the device remains in an undefined state, preventing reuse.

Disable FLR for this device so the PCI core falls back to working reset
methods (PM reset or bus reset).

This follows the existing pattern used for the MediaTek MT7922 WiFi
(14c3:0616), which is the predecessor device and already uses this quirk.

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
v2:
  - Change from device-specific D3cold reset to quirk_no_flr() approach
    based on maintainer feedback (Alex Williamson)
  - Follow existing pattern used by MediaTek MT7922 (0x0616)
v1: https://lore.kernel.org/all/20260507142916.392983-1-jtornosm@redhat.com/

 drivers/pci/quirks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 000000000000..111111111111 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5607,6 +5607,7 @@
  * Intel 82579LM Gigabit Ethernet Controller 0x1502
  * Intel 82579V Gigabit Ethernet Controller 0x1503
  * Mediatek MT7922 802.11ax PCI Express Wireless Network Adapter
+ * Mediatek MT7925 802.11be PCI Express Wireless Network Adapter
  */
 static void quirk_no_flr(struct pci_dev *dev)
 {
@@ -5617,6 +5618,7 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AMD, 0x7901, quirk_no_flr);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_no_flr);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_no_flr);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_MEDIATEK, 0x0616, quirk_no_flr);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_MEDIATEK, 0x7925, quirk_no_flr);

 /* FLR may cause the SolidRun SNET DPU (rev 0x1) to hang */
 static void quirk_no_flr_snet(struct pci_dev *dev)
--
2.53.0