[PATCH 2/4] wifi: mt76: mt7615: wait while Bluetooth downloads the MT7663 patch

[Ryan Brue]

On MT7663 the Bluetooth SDIO function (btmtksdio) shares the ROM patch
with Wi-Fi, guarded by a semaphore in the firmware. When Bluetooth wins
the race at boot and is downloading the patch, the semaphore request
returns PATCH_NOT_DL_SEM_FAIL and mt7663s gave up:

  mt7663s mmc2:0001:1: Failed to get patch semaphore
  mt7663s mmc2:0001:1: failed to load mediatek/mt7663pr2h_rebb.bin

Retry every 100 ms, for up to 5 s, while the semaphore is held, then
find the patch downloaded. Tested on an MT7663 SDIO module with
btmtksdio built in: across repeated boots, whichever function downloads
the patch, both come up.

Fixes: a66cbdd6573d ("mt76: mt7615: introduce mt7663s support")
Signed-off-by: Ryan Brue <ryanbrue.dev at gmail.com>
---
 drivers/net/wireless/mediatek/mt76/mt7615/mcu.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
index 152b75178b27..e5c2ad5fb458 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
@@ -1241,7 +1241,7 @@ static int mt7615_load_patch(struct mt7615_dev *dev, u32 addr, const char *name)
 {
 	const struct mt7615_patch_hdr *hdr;
 	const struct firmware *fw = NULL;
-	int len, ret, sem;
+	int i, len, ret, sem;
 
 	ret = firmware_request_nowarn(&fw, name, dev->mt76.dev);
 	if (ret)
@@ -1253,7 +1253,17 @@ static int mt7615_load_patch(struct mt7615_dev *dev, u32 addr, const char *name)
 		goto release_fw;
 	}
 
-	sem = mt76_connac_mcu_patch_sem_ctrl(&dev->mt76, true);
+	/*
+	 * On MT7663 the Bluetooth function shares the ROM patch, and the
+	 * semaphore is refused while it downloads the patch: wait for it.
+	 */
+	for (i = 0; i < 50; i++) {
+		sem = mt76_connac_mcu_patch_sem_ctrl(&dev->mt76, true);
+		if (sem != PATCH_NOT_DL_SEM_FAIL)
+			break;
+		msleep(100);
+	}
+
 	switch (sem) {
 	case PATCH_IS_DL:
 		goto release_fw;

-- 
2.55.0