[PATCH wireless-next] wifi: rt2x00: rt2800lib: fallback to default RF config when EEPROM_NIC_CONF0 is 0x0000

[Alessandro Petrozzelli via B4 Relay <devnull+apetrozzelli.gmail.com@kernel.org>]

From: Alessandro Petrozzelli <apetrozzelli@gmail.com>

On some Ralink PCI/PCIe wireless cards, such as the AzureWave AW-NE766
(Ralink RT2790 / RT2872, PCI ID 1814:0781, subsystem 1814:2790) bundled
in the ASUS EeeBox PC B202, reading EEPROM_NIC_CONF0 returns 0x0000
instead of 0xffff when the EEPROM word is uninitialized.

Currently, rt2800_validate_eeprom() only triggers the default RF2820
(1T2R) configuration fallback when EEPROM_NIC_CONF0 is 0xffff, unlike
other EEPROM validation checks in the same function (such as LNA gain
fields) which already check for both 0x00 and 0xff. As a result,
EEPROM_NIC_CONF0_RF_TYPE remains 0x0000 and rt2800_init_eeprom() aborts
device initialization with -ENODEV:

  rt2x00_set_rt: Info - RT chipset 2872, rev 0200 detected
  rt2800_init_eeprom: Error - Invalid RF chipset 0x0000 detected
  rt2x00lib_probe_dev: Error - Failed to allocate device

Since 0x0000 is never a valid RF_TYPE (valid chipsets start at
RF2820 = 0x0001), extend the EEPROM_NIC_CONF0 fallback check to also
handle 0x0000 so that these cards initialize and operate properly.

Signed-off-by: Alessandro Petrozzelli <apetrozzelli@gmail.com>
---
 drivers/net/wireless/ralink/rt2x00/rt2800lib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800lib.c b/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
index 2e2e382b6..dda5ba2ad 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
@@ -11047,7 +11047,7 @@ static int rt2800_validate_eeprom(struct rt2x00_dev *rt2x00dev)
 		return retval;
 
 	word = rt2800_eeprom_read(rt2x00dev, EEPROM_NIC_CONF0);
-	if (word == 0xffff) {
+	if (word == 0xffff || word == 0x0000) {
 		rt2x00_set_field16(&word, EEPROM_NIC_CONF0_RXPATH, 2);
 		rt2x00_set_field16(&word, EEPROM_NIC_CONF0_TXPATH, 1);
 		rt2x00_set_field16(&word, EEPROM_NIC_CONF0_RF_TYPE, RF2820);

---
base-commit: 2c50cd5d10e8723797f28c7978f1f61688e0c0d2
change-id: 20261031-fix-rt2800-eeprom-nic-conf0-zero-acf88f6ddd60

Best regards,
--  
Alessandro Petrozzelli <apetrozzelli@gmail.com>