[PATCH mt76-next 16/25] wifi: mt76: mt7921: honour the valid flag in efuse block reads

[Felix Fietkau <nbd@nbd.name>]

mt7921_mcu_read_eeprom() ignores the valid flag of the EFUSE_ACCESS
response. For an unwritten efuse block, mt7921_load_clc() thus selects
the CLC records by an undefined hardware type.

Return -ENODATA for an invalid block, like mt7915_mcu_get_eeprom().
mt7921_load_clc() then keeps the hardware type 0, which it also uses on
USB and SDIO, where it does not read the field.

Fixes: 23bdc5d8cadf ("wifi: mt76: mt7921: introduce Country Location Control support")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/wireless/mediatek/mt76/mt7921/mcu.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
index a0caa77339ee..242a4415539e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
@@ -111,6 +111,11 @@ static int mt7921_mcu_read_eeprom(struct mt792x_dev *dev, u32 offset, u8 *val)
 	}
 
 	res = (struct mt7921_mcu_eeprom_info *)skb->data;
+	if (!le32_to_cpu(res->valid)) {
+		dev_kfree_skb(skb);
+		return -ENODATA;
+	}
+
 	*val = res->data[offset % MT7921_EEPROM_BLOCK_SIZE];
 	dev_kfree_skb(skb);
 
@@ -453,7 +458,7 @@ static int mt7921_load_clc(struct mt792x_dev *dev, const char *fw_name)
 
 	if (mt76_is_mmio(&dev->mt76)) {
 		ret = mt7921_mcu_read_eeprom(dev, MT_EE_HW_TYPE, &hw_encap);
-		if (ret)
+		if (ret && ret != -ENODATA)
 			return ret;
 		hw_encap = u8_get_bits(hw_encap, MT_EE_HW_TYPE_ENCAP);
 	}
-- 
2.47.3