[PATCH] wifi: mt76: mt7921e: Perform FLR to recovery the device

[Kai-Heng Feng]

When "Pre-boot WiFi" is enabled in BIOS, the mt7921e device may not
work:
mt7921e 0000:02:00.0: ASIC revision: 79220010
mt7921e 0000:02:00.0: Message 00000010 (seq 1) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 2) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 3) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 4) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 5) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 6) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 7) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 8) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 9) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: Message 00000010 (seq 10) timeout
mt7921e 0000:02:00.0: Failed to get patch semaphore
mt7921e 0000:02:00.0: hardware init failed

After some trials and errors, it shows that PCI function level reset can
recover the device back to a functional state.

So perform FLR at probe routine to workaround the issue.

Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
 drivers/net/wireless/mediatek/mt76/mt7921/pci.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
index ddb1fa4ee01d..9671fbe35a8e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
@@ -262,6 +262,10 @@ static int mt7921_pci_probe(struct pci_dev *pdev,
 	int ret;
 	u16 cmd;
 
+	ret = pci_reset_function_locked(pdev);
+	if (ret)
+		pci_info(pdev, "Unable to perform FLR\n");
+
 	ret = pcim_enable_device(pdev);
 	if (ret)
 		return ret;
-- 
2.34.1