[PATCH wireless-next 2/8] wifi: rt2800: calibrate the crystal of RT3593 with the beacons
From: Ho Jie Feng
Date: Thu Oct 29 2026 - 09:54:05 EST
On a Netgear WNDA4100 (RT3593), as the adapter warms up, the
frequency offset drifts enough to affect the link quality.
In certain cases it can cause the link speed to drop
to 1Mbit/s or below.
Add a frequency calibration step function to RT3593 to use
the frequency offset obtained from the beacon frames of the AP
for tuning.
Test results:
before after
TX 27.7 28.5
RX 31.6 69.7
Signed-off-by: Ho Jie Feng <hjf3108@xxxxxxxxx>
---
drivers/net/wireless/ralink/rt2x00/rt2800.h | 1 +
.../net/wireless/ralink/rt2x00/rt2800lib.c | 101 ++++++++++++++++++
.../net/wireless/ralink/rt2x00/rt2800lib.h | 4 +
.../net/wireless/ralink/rt2x00/rt2800usb.c | 1 +
drivers/net/wireless/ralink/rt2x00/rt2x00.h | 6 ++
.../net/wireless/ralink/rt2x00/rt2x00lib.h | 2 +
.../net/wireless/ralink/rt2x00/rt2x00link.c | 9 ++
7 files changed, 124 insertions(+)
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800.h b/drivers/net/wireless/ralink/rt2x00/rt2800.h
index 8930589b4967d..b9f6de3a462e3 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800.h
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800.h
@@ -3163,6 +3163,7 @@ enum rt2800_eeprom_word {
*/
#define RXWI_W3_SNR0 FIELD32(0x000000ff)
#define RXWI_W3_SNR1 FIELD32(0x0000ff00)
+#define RXWI_W3_FOFFSET FIELD32(0xff000000)
/*
* Macros for converting txpower from EEPROM to mac80211 value
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800lib.c b/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
index 2e2e382b62475..e7b6edf485099 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
@@ -897,6 +897,28 @@ static int rt2800_agc_to_rssi(struct rt2x00_dev *rt2x00dev, u32 rxwi_w2)
return (int)max(rssi0, rssi2);
}
+static void rt2800_rx_freq_offset(struct queue_entry *entry,
+ struct rxdone_entry_desc *rxdesc)
+{
+ struct rt2800_drv_data *drv_data = entry->queue->rt2x00dev->drv_data;
+ __le32 *rxwi = (__le32 *) entry->skb->data;
+ struct ieee80211_hdr *hdr =
+ (void *)(entry->skb->data + entry->queue->winfo_size);
+ u32 word;
+
+ if (!(rxdesc->dev_flags & RXDONE_MY_BSS) ||
+ (rxdesc->flags & RX_FLAG_FAILED_FCS_CRC) ||
+ !ieee80211_is_beacon(hdr->frame_control))
+ return;
+
+ word = rt2x00_desc_read(rxwi, 3);
+
+ spin_lock_bh(&drv_data->bcn_lock);
+ drv_data->bcn_freq_offset = rt2x00_get_field32(word, RXWI_W3_FOFFSET);
+ drv_data->bcn_rate_mode = rxdesc->rate_mode;
+ spin_unlock_bh(&drv_data->bcn_lock);
+}
+
void rt2800_process_rxwi(struct queue_entry *entry,
struct rxdone_entry_desc *rxdesc)
{
@@ -935,6 +957,14 @@ void rt2800_process_rxwi(struct queue_entry *entry,
* Convert descriptor AGC value to RSSI value.
*/
rxdesc->rssi = rt2800_agc_to_rssi(entry->queue->rt2x00dev, word);
+
+ /*
+ * The frequency offset of the beacons is used for the frequency
+ * calibration.
+ */
+ if (rt2x00_rt(entry->queue->rt2x00dev, RT3593))
+ rt2800_rx_freq_offset(entry, rxdesc);
+
/*
* Remove RXWI descriptor from start of the buffer.
*/
@@ -2443,6 +2473,7 @@ static inline bool rt2800_clk_is_20mhz(struct rt2x00_dev *rt2x00dev)
}
#define FREQ_OFFSET_BOUND 0x5f
+#define FREQ_OFFSET_INVALID -128
static void rt2800_freq_cal_mode1(struct rt2x00_dev *rt2x00dev)
{
@@ -5633,6 +5664,73 @@ void rt2800_vco_calibration(struct rt2x00_dev *rt2x00dev)
}
EXPORT_SYMBOL_GPL(rt2800_vco_calibration);
+void rt2800_freq_calibration(struct rt2x00_dev *rt2x00dev)
+{
+ struct rt2800_drv_data *drv_data = rt2x00dev->drv_data;
+ struct link *link = &rt2x00dev->link;
+ u8 activate_threshold, deactivate_threshold;
+ u8 freq_offset, rate_mode;
+ u16 eeprom;
+ s8 offset;
+
+ if (!rt2x00_rt(rt2x00dev, RT3593))
+ return;
+
+ if (!rt2x00dev->intf_associated) {
+ eeprom = rt2800_eeprom_read(rt2x00dev, EEPROM_FREQ);
+ rt2x00dev->freq_offset = rt2x00_get_field16(eeprom,
+ EEPROM_FREQ_OFFSET);
+ link->freq_cal_adjusting = false;
+ return;
+ }
+
+ spin_lock_bh(&drv_data->bcn_lock);
+ offset = drv_data->bcn_freq_offset;
+ rate_mode = drv_data->bcn_rate_mode;
+ drv_data->bcn_freq_offset = FREQ_OFFSET_INVALID;
+ spin_unlock_bh(&drv_data->bcn_lock);
+
+ /* No beacons received */
+ if (offset == FREQ_OFFSET_INVALID)
+ return;
+
+ if (rate_mode == RATE_MODE_CCK) {
+ activate_threshold = 4;
+ deactivate_threshold = 2;
+ } else {
+ activate_threshold = 20;
+ deactivate_threshold = 10;
+ }
+
+ /* Hysteresis */
+ if (abs(offset) >= activate_threshold)
+ link->freq_cal_adjusting = true;
+ else if (abs(offset) <= deactivate_threshold)
+ link->freq_cal_adjusting = false;
+
+ if (!link->freq_cal_adjusting)
+ return;
+
+ freq_offset = rt2x00_get_field8(rt2x00dev->freq_offset, RFCSR17_CODE);
+ freq_offset = min_t(u8, freq_offset, FREQ_OFFSET_BOUND);
+
+ if (offset > 0) {
+ if (freq_offset > 0)
+ freq_offset--;
+ else
+ link->freq_cal_adjusting = false;
+ } else {
+ if (freq_offset < FREQ_OFFSET_BOUND)
+ freq_offset++;
+ else
+ link->freq_cal_adjusting = false;
+ }
+
+ rt2x00dev->freq_offset = freq_offset;
+ rt2800_freq_cal_mode1(rt2x00dev);
+}
+EXPORT_SYMBOL_GPL(rt2800_freq_calibration);
+
static void rt2800_config_retry_limit(struct rt2x00_dev *rt2x00dev,
struct rt2x00lib_conf *libconf)
{
@@ -12032,6 +12130,7 @@ static int rt2800_probe_rt(struct rt2x00_dev *rt2x00dev)
int rt2800_probe_hw(struct rt2x00_dev *rt2x00dev)
{
+ struct rt2800_drv_data *drv_data = rt2x00dev->drv_data;
int retval;
u32 reg;
@@ -12105,6 +12204,8 @@ int rt2800_probe_hw(struct rt2x00_dev *rt2x00dev)
*/
rt2x00dev->rssi_offset = DEFAULT_RSSI_OFFSET;
+ spin_lock_init(&drv_data->bcn_lock);
+
return 0;
}
EXPORT_SYMBOL_GPL(rt2800_probe_hw);
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800lib.h b/drivers/net/wireless/ralink/rt2x00/rt2800lib.h
index a3c3a751f57e3..9a04a0fba113f 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800lib.h
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800lib.h
@@ -45,6 +45,9 @@ struct rt2800_drv_data {
unsigned int ampdu_factor_cnt[4];
DECLARE_BITMAP(sta_ids, STA_IDS_SIZE);
struct ieee80211_sta *wcid_to_sta[STA_IDS_SIZE];
+ spinlock_t bcn_lock; /* protects bcn_freq_offset, bcn_rate_mode */
+ s8 bcn_freq_offset;
+ u8 bcn_rate_mode;
};
struct rt2800_ops {
@@ -241,6 +244,7 @@ void rt2800_link_tuner(struct rt2x00_dev *rt2x00dev, struct link_qual *qual,
const u32 count);
void rt2800_gain_calibration(struct rt2x00_dev *rt2x00dev);
void rt2800_vco_calibration(struct rt2x00_dev *rt2x00dev);
+void rt2800_freq_calibration(struct rt2x00_dev *rt2x00dev);
int rt2800_enable_radio(struct rt2x00_dev *rt2x00dev);
void rt2800_disable_radio(struct rt2x00_dev *rt2x00dev);
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800usb.c b/drivers/net/wireless/ralink/rt2x00/rt2800usb.c
index 15de3db124298..387c07e2251b7 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800usb.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800usb.c
@@ -693,6 +693,7 @@ static const struct rt2x00lib_ops rt2800usb_rt2x00_ops = {
.link_tuner = rt2800_link_tuner,
.gain_calibration = rt2800_gain_calibration,
.vco_calibration = rt2800_vco_calibration,
+ .freq_calibration = rt2800_freq_calibration,
.watchdog = rt2800_watchdog,
.start_queue = rt2800usb_start_queue,
.kick_queue = rt2x00usb_kick_queue,
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00.h b/drivers/net/wireless/ralink/rt2x00/rt2x00.h
index 7d313e86d3f20..a80508db32d9c 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00.h
@@ -319,6 +319,11 @@ struct link {
*/
struct ewma_rssi avg_rssi;
+ /*
+ * Controls interval of frequency calibration
+ */
+ bool freq_cal_adjusting;
+
/*
* Work structure for scheduling periodic link tuning.
*/
@@ -559,6 +564,7 @@ struct rt2x00lib_ops {
struct link_qual *qual, const u32 count);
void (*gain_calibration) (struct rt2x00_dev *rt2x00dev);
void (*vco_calibration) (struct rt2x00_dev *rt2x00dev);
+ void (*freq_calibration) (struct rt2x00_dev *rt2x00dev);
/*
* Data queue handlers.
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00lib.h b/drivers/net/wireless/ralink/rt2x00/rt2x00lib.h
index 2f1385baa7ae9..a6f516ebdb2db 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00lib.h
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00lib.h
@@ -22,6 +22,8 @@
#define LINK_TUNE_INTERVAL round_jiffies_relative(LINK_TUNE_SECONDS * HZ)
#define AGC_SECONDS 4
#define VCO_SECONDS 10
+#define FREQ_SECONDS 10
+#define FREQ_ADJUST_SECONDS 1
/*
* rt2x00_rate: Per rate device information
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00link.c b/drivers/net/wireless/ralink/rt2x00/rt2x00link.c
index fb23d409fba87..2dc4edc12834f 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00link.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00link.c
@@ -343,6 +343,7 @@ static void rt2x00link_tuner(struct work_struct *work)
struct rt2x00_dev *rt2x00dev =
container_of(work, struct rt2x00_dev, link.work.work);
struct link *link = &rt2x00dev->link;
+ unsigned int freq_interval;
/*
* When the radio is shutting down we should
@@ -362,6 +363,14 @@ static void rt2x00link_tuner(struct work_struct *work)
(link->count % (AGC_SECONDS / LINK_TUNE_SECONDS)) == 0)
rt2x00dev->ops->lib->gain_calibration(rt2x00dev);
+ freq_interval = link->freq_cal_adjusting ?
+ FREQ_ADJUST_SECONDS : FREQ_SECONDS;
+
+ /* VCO calibration should be done after frequency calibration */
+ if (rt2x00dev->ops->lib->freq_calibration &&
+ (link->count % (freq_interval / LINK_TUNE_SECONDS)) == 0)
+ rt2x00dev->ops->lib->freq_calibration(rt2x00dev);
+
if (rt2x00dev->ops->lib->vco_calibration &&
rt2x00_has_cap_vco_recalibration(rt2x00dev) &&
(link->count % (VCO_SECONDS / LINK_TUNE_SECONDS)) == 0)
--
2.53.0