From: Corentin Labbe [ Upstream commit 0a2581cbae9e442835f68d22044157db61cdf54d ] I have an hostapd setup with a 01:00.0 Network controller: Ralink corp. RT2790 Wireless 802.11n 1T/2R PCIe The setup work fine on 6.18.26-gentoo It breaks on 6.18.33-gentoo (and still broken on 6.18.37) I found an hint in dmesg: On 6.18.26-gentoo I see: May 31 15:48:45 trash01 kernel: ieee80211 phy0: rt2x00_set_rf: Info - RF chipset 0003 detected On 6.18.33-gentoo I see: May 31 15:22:57 trash01 kernel: ieee80211 phy0: rt2x00_set_rf: Info - RF chipset 0006 detected The RF chipset seems badly detected. The problem was the EEPROM which was badly initialized. Probably the origin was in some PCI change but unfortunately I couldn't play to bisect/reboot often the board with this card to do it. Signed-off-by: Corentin Labbe Acked-by: Stanislaw Gruszka Link: https://patch.msgid.link/20260703134932.3786771-1-clabbe@baylibre.com Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: The background `git log -S "PCI_EEPROM_QUIRK_EXTRA_READ_CYCLE"` search finished, but this shallow 6.18.44 checkout only surfaced merge commits — not the original introducing change. From external history, that quirk came in **7738a7a** (`misc: eeprom: eeprom_93cx6: Add quirk for extra read clock cycle`, Oct 2024). That lines up with the regression: rt2x00 PCI drivers never zero-initialized the new `quirks` field, so EEPROM reads could be corrupted and RF chipset detection could fail. The backport analysis stands: **YES** for this 6.18.y tree. drivers/net/wireless/ralink/rt2x00/rt2400pci.c | 2 +- drivers/net/wireless/ralink/rt2x00/rt2500pci.c | 2 +- drivers/net/wireless/ralink/rt2x00/rt2800pci.c | 2 +- drivers/net/wireless/ralink/rt2x00/rt61pci.c | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/net/wireless/ralink/rt2x00/rt2400pci.c b/drivers/net/wireless/ralink/rt2x00/rt2400pci.c index 42e21e9f303b2..15073b856adf9 100644 --- a/drivers/net/wireless/ralink/rt2x00/rt2400pci.c +++ b/drivers/net/wireless/ralink/rt2x00/rt2400pci.c @@ -1429,7 +1429,7 @@ static irqreturn_t rt2400pci_interrupt(int irq, void *dev_instance) */ static int rt2400pci_validate_eeprom(struct rt2x00_dev *rt2x00dev) { - struct eeprom_93cx6 eeprom; + struct eeprom_93cx6 eeprom = {}; u32 reg; u16 word; u8 *mac; diff --git a/drivers/net/wireless/ralink/rt2x00/rt2500pci.c b/drivers/net/wireless/ralink/rt2x00/rt2500pci.c index 36ddc5a69fa40..3536a0f311171 100644 --- a/drivers/net/wireless/ralink/rt2x00/rt2500pci.c +++ b/drivers/net/wireless/ralink/rt2x00/rt2500pci.c @@ -1555,7 +1555,7 @@ static irqreturn_t rt2500pci_interrupt(int irq, void *dev_instance) */ static int rt2500pci_validate_eeprom(struct rt2x00_dev *rt2x00dev) { - struct eeprom_93cx6 eeprom; + struct eeprom_93cx6 eeprom = {}; u32 reg; u16 word; u8 *mac; diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800pci.c b/drivers/net/wireless/ralink/rt2x00/rt2800pci.c index 14c45aba836f2..853fd31d13629 100644 --- a/drivers/net/wireless/ralink/rt2x00/rt2800pci.c +++ b/drivers/net/wireless/ralink/rt2x00/rt2800pci.c @@ -108,7 +108,7 @@ static void rt2800pci_eepromregister_write(struct eeprom_93cx6 *eeprom) static int rt2800pci_read_eeprom_pci(struct rt2x00_dev *rt2x00dev) { - struct eeprom_93cx6 eeprom; + struct eeprom_93cx6 eeprom = {}; u32 reg; reg = rt2x00mmio_register_read(rt2x00dev, E2PROM_CSR); diff --git a/drivers/net/wireless/ralink/rt2x00/rt61pci.c b/drivers/net/wireless/ralink/rt2x00/rt61pci.c index d1cd5694e3c73..5dca2afb4b96c 100644 --- a/drivers/net/wireless/ralink/rt2x00/rt61pci.c +++ b/drivers/net/wireless/ralink/rt2x00/rt61pci.c @@ -2298,7 +2298,7 @@ static irqreturn_t rt61pci_interrupt(int irq, void *dev_instance) */ static int rt61pci_validate_eeprom(struct rt2x00_dev *rt2x00dev) { - struct eeprom_93cx6 eeprom; + struct eeprom_93cx6 eeprom = {}; u32 reg; u16 word; u8 *mac; -- 2.53.0