* [PATCH rtw-next] wifi: rtl8xxxu: Detect the maximum supported channel width
@ 2026-04-25 19:38 Bitterblue Smith
2026-04-27 2:50 ` Ping-Ke Shih
0 siblings, 1 reply; 2+ messages in thread
From: Bitterblue Smith @ 2026-04-25 19:38 UTC (permalink / raw)
To: linux-wireless@vger.kernel.org; +Cc: Ping-Ke Shih, Jes Sorensen, art1310
Some devices malfunction when connected to a network with 40 MHz channel
width, because they don't support that.
RTL8188FU, RTL8192FU, and RTL8710BU (RTL8188GU) have a way to signal
this (and some other capabilities) to the driver. Get this information
from the hardware and advertise 40 MHz support only when the hardware
can handle it. We assume the other chips can always handle it.
RTL8710BU needs a different way to retrieve this information, which will
be implemented some other time.
Fixes: dbf9b7bb0edf ("wifi: rtl8xxxu: Enable 40 MHz width by default")
Cc: stable@vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221394
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
drivers/net/wireless/realtek/rtl8xxxu/8188e.c | 1 +
drivers/net/wireless/realtek/rtl8xxxu/8188f.c | 1 +
drivers/net/wireless/realtek/rtl8xxxu/8192c.c | 1 +
drivers/net/wireless/realtek/rtl8xxxu/8192e.c | 1 +
drivers/net/wireless/realtek/rtl8xxxu/8192f.c | 1 +
drivers/net/wireless/realtek/rtl8xxxu/8710b.c | 1 +
drivers/net/wireless/realtek/rtl8xxxu/8723a.c | 1 +
drivers/net/wireless/realtek/rtl8xxxu/8723b.c | 1 +
drivers/net/wireless/realtek/rtl8xxxu/core.c | 64 +++++++++++++++++--
drivers/net/wireless/realtek/rtl8xxxu/regs.h | 2 +
.../net/wireless/realtek/rtl8xxxu/rtl8xxxu.h | 7 ++
11 files changed, 76 insertions(+), 5 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/8188e.c b/drivers/net/wireless/realtek/rtl8xxxu/8188e.c
index 93f11ea26b90..3f3fe5b1d486 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/8188e.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/8188e.c
@@ -1867,6 +1867,7 @@ struct rtl8xxxu_fileops rtl8188eu_fops = {
.has_tx_report = 1,
.init_reg_pkt_life_time = 1,
.gen2_thermal_meter = 1,
+ .hw_feature_report = 0,
.max_sec_cam_num = 32,
.adda_1t_init = 0x0b1b25a0,
.adda_1t_path_on = 0x0bdb25a0,
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/8188f.c b/drivers/net/wireless/realtek/rtl8xxxu/8188f.c
index 13a6d9b22edb..4aac2a598ba7 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/8188f.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/8188f.c
@@ -1746,6 +1746,7 @@ struct rtl8xxxu_fileops rtl8188fu_fops = {
.init_reg_rxfltmap = 1,
.init_reg_pkt_life_time = 1,
.init_reg_hmtfr = 1,
+ .hw_feature_report = 1,
.ampdu_max_time = 0x70,
.ustime_tsf_edca = 0x28,
.max_aggr_num = 0x0c14,
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/8192c.c b/drivers/net/wireless/realtek/rtl8xxxu/8192c.c
index cbf72fa317d3..56657051c82e 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/8192c.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/8192c.c
@@ -724,6 +724,7 @@ struct rtl8xxxu_fileops rtl8192cu_fops = {
.tx_desc_size = sizeof(struct rtl8xxxu_txdesc32),
.rx_desc_size = sizeof(struct rtl8xxxu_rxdesc16),
.supports_ap = 1,
+ .hw_feature_report = 0,
.max_macid_num = 32,
.max_sec_cam_num = 32,
.adda_1t_init = 0x0b1b25a0,
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/8192e.c b/drivers/net/wireless/realtek/rtl8xxxu/8192e.c
index bc2c5c07c4de..6e6ccd23660c 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/8192e.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/8192e.c
@@ -1752,6 +1752,7 @@ struct rtl8xxxu_fileops rtl8192eu_fops = {
.has_s0s1 = 0,
.gen2_thermal_meter = 1,
.needs_full_init = 1,
+ .hw_feature_report = 0,
.supports_ap = 1,
.max_macid_num = 128,
.max_sec_cam_num = 64,
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/8192f.c b/drivers/net/wireless/realtek/rtl8xxxu/8192f.c
index 94cb5809bed0..57c902f2c2de 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/8192f.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/8192f.c
@@ -2075,6 +2075,7 @@ struct rtl8xxxu_fileops rtl8192fu_fops = {
.init_reg_rxfltmap = 1,
.init_reg_pkt_life_time = 1,
.init_reg_hmtfr = 1,
+ .hw_feature_report = 1,
.ampdu_max_time = 0x5e,
.ustime_tsf_edca = 0x50,
.max_aggr_num = 0x1f1f,
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/8710b.c b/drivers/net/wireless/realtek/rtl8xxxu/8710b.c
index 5bf04ea82f6f..43804677349e 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/8710b.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/8710b.c
@@ -1853,6 +1853,7 @@ struct rtl8xxxu_fileops rtl8710bu_fops = {
.init_reg_rxfltmap = 1,
.init_reg_pkt_life_time = 1,
.init_reg_hmtfr = 1,
+ .hw_feature_report = 0, /* TODO, it's different */
.ampdu_max_time = 0x5e,
/*
* The RTL8710BU vendor driver uses 0x50 here and it works fine,
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/8723a.c b/drivers/net/wireless/realtek/rtl8xxxu/8723a.c
index 303f89395952..621703d8ae2d 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/8723a.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/8723a.c
@@ -633,6 +633,7 @@ struct rtl8xxxu_fileops rtl8723au_fops = {
.rx_agg_buf_size = 16000,
.tx_desc_size = sizeof(struct rtl8xxxu_txdesc32),
.rx_desc_size = sizeof(struct rtl8xxxu_rxdesc16),
+ .hw_feature_report = 0,
.max_sec_cam_num = 32,
.adda_1t_init = 0x0b1b25a0,
.adda_1t_path_on = 0x0bdb25a0,
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/8723b.c b/drivers/net/wireless/realtek/rtl8xxxu/8723b.c
index bb747420ff7e..52b0e90338ef 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/8723b.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/8723b.c
@@ -1747,6 +1747,7 @@ struct rtl8xxxu_fileops rtl8723bu_fops = {
.gen2_thermal_meter = 1,
.needs_full_init = 1,
.init_reg_hmtfr = 1,
+ .hw_feature_report = 0,
.ampdu_max_time = 0x5e,
.ustime_tsf_edca = 0x50,
.max_aggr_num = 0x0c14,
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c b/drivers/net/wireless/realtek/rtl8xxxu/core.c
index 2c56d7df92a7..506633b3b51c 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
@@ -14,6 +14,7 @@
*/
#include <linux/firmware.h>
+#include <linux/iopoll.h>
#include "regs.h"
#include "rtl8xxxu.h"
@@ -3936,6 +3937,46 @@ static inline u8 rtl8xxxu_get_macid(struct rtl8xxxu_priv *priv,
return sta_info->macid;
}
+static void rtl8xxxu_request_hw_feature(struct rtl8xxxu_priv *priv)
+{
+ if (!priv->fops->hw_feature_report)
+ return;
+
+ rtl8xxxu_write8(priv, REG_C2HEVT_MSG_NORMAL, C2H_HW_FEATURE_DUMP);
+}
+
+static int rtl8xxxu_dump_hw_feature(struct rtl8xxxu_priv *priv)
+{
+ static const u8 bw_map[8] = { 0, 0, 160, 5, 10, 20, 40, 80 };
+ struct rtl8xxxu_hw_feature *hw_feature = &priv->hw_feature;
+ u8 feature[13];
+ int i, ret;
+ u8 id, bw;
+
+ if (!priv->fops->hw_feature_report) {
+ hw_feature->max_bw = 40;
+ return 0;
+ }
+
+ ret = read_poll_timeout(rtl8xxxu_read8, id,
+ id == C2H_HW_FEATURE_REPORT,
+ 10000, 800000, false,
+ priv, REG_C2HEVT_MSG_NORMAL);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < ARRAY_SIZE(feature); i++)
+ feature[i] = rtl8xxxu_read8(priv, REG_C2HEVT_MSG_NORMAL + 2 + i);
+
+ rtl8xxxu_write8(priv, REG_C2HEVT_MSG_NORMAL, 0);
+
+ bw = u8_get_bits(feature[6], GENMASK(2, 0));
+
+ hw_feature->max_bw = bw_map[bw];
+
+ return 0;
+}
+
static int rtl8xxxu_init_device(struct ieee80211_hw *hw)
{
struct rtl8xxxu_priv *priv = hw->priv;
@@ -3982,6 +4023,8 @@ static int rtl8xxxu_init_device(struct ieee80211_hw *hw)
*/
rtl8xxxu_write16(priv, REG_TRXFF_BNDY + 2, fops->trxff_boundary);
+ rtl8xxxu_request_hw_feature(priv);
+
for (int retry = 5; retry >= 0 ; retry--) {
ret = rtl8xxxu_download_firmware(priv);
dev_dbg(dev, "%s: download_firmware %i\n", __func__, ret);
@@ -3997,6 +4040,12 @@ static int rtl8xxxu_init_device(struct ieee80211_hw *hw)
if (ret)
goto exit;
+ ret = rtl8xxxu_dump_hw_feature(priv);
+ if (ret) {
+ dev_err(dev, "failed to dump hw feature\n");
+ goto exit;
+ }
+
if (fops->phy_init_antenna_selection)
fops->phy_init_antenna_selection(priv);
@@ -7876,15 +7925,20 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
sband->ht_cap.ht_supported = true;
sband->ht_cap.ampdu_factor = IEEE80211_HT_MAX_AMPDU_64K;
sband->ht_cap.ampdu_density = IEEE80211_HT_MPDU_DENSITY_16;
- sband->ht_cap.cap = IEEE80211_HT_CAP_SGI_20 | IEEE80211_HT_CAP_SGI_40 |
- IEEE80211_HT_CAP_SUP_WIDTH_20_40;
+ sband->ht_cap.cap = IEEE80211_HT_CAP_SGI_20;
+
+ if (priv->hw_feature.max_bw >= 40) {
+ sband->ht_cap.cap |= IEEE80211_HT_CAP_SGI_40;
+ sband->ht_cap.cap |= IEEE80211_HT_CAP_SUP_WIDTH_20_40;
+ } else {
+ dev_info(&udev->dev, "hardware doesn't support HT40\n");
+ }
+
memset(&sband->ht_cap.mcs, 0, sizeof(sband->ht_cap.mcs));
sband->ht_cap.mcs.rx_mask[0] = 0xff;
sband->ht_cap.mcs.rx_mask[4] = 0x01;
- if (priv->rf_paths > 1) {
+ if (priv->rf_paths > 1)
sband->ht_cap.mcs.rx_mask[1] = 0xff;
- sband->ht_cap.cap |= IEEE80211_HT_CAP_SGI_40;
- }
sband->ht_cap.mcs.tx_params = IEEE80211_HT_MCS_TX_DEFINED;
hw->wiphy->bands[NL80211_BAND_2GHZ] = sband;
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/regs.h b/drivers/net/wireless/realtek/rtl8xxxu/regs.h
index 0741db8d08bf..eafaef1438b9 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/regs.h
+++ b/drivers/net/wireless/realtek/rtl8xxxu/regs.h
@@ -447,6 +447,8 @@
/* 8188EU */
#define REG_32K_CTRL 0x0194
#define REG_C2HEVT_MSG_NORMAL 0x01a0
+#define C2H_HW_FEATURE_REPORT 0x19
+#define C2H_HW_FEATURE_DUMP 0xfd
/* 8192EU/8723BU/8812 */
#define REG_C2HEVT_CMD_ID_8723B 0x01ae
#define REG_C2HEVT_CLEAR 0x01af
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
index 188f4bbe99cd..b667e5d413ac 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
+++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
@@ -1790,11 +1790,17 @@ struct rtl8xxxu_cfo_tracking {
#define RTL8XXXU_MAX_SEC_CAM_NUM 64
#define RTL8XXXU_SEC_DEFAULT_KEY_NUM 4
+struct rtl8xxxu_hw_feature {
+ u8 max_bw;
+};
+
struct rtl8xxxu_priv {
struct ieee80211_hw *hw;
struct usb_device *udev;
struct rtl8xxxu_fileops *fops;
+ struct rtl8xxxu_hw_feature hw_feature;
+
spinlock_t tx_urb_lock;
struct list_head tx_urb_free_list;
int tx_urb_free_count;
@@ -2011,6 +2017,7 @@ struct rtl8xxxu_fileops {
u8 init_reg_pkt_life_time:1;
u8 init_reg_hmtfr:1;
u8 supports_concurrent:1;
+ u8 hw_feature_report:1;
u8 ampdu_max_time;
u8 ustime_tsf_edca;
u16 max_aggr_num;
--
2.53.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* RE: [PATCH rtw-next] wifi: rtl8xxxu: Detect the maximum supported channel width
2026-04-25 19:38 [PATCH rtw-next] wifi: rtl8xxxu: Detect the maximum supported channel width Bitterblue Smith
@ 2026-04-27 2:50 ` Ping-Ke Shih
0 siblings, 0 replies; 2+ messages in thread
From: Ping-Ke Shih @ 2026-04-27 2:50 UTC (permalink / raw)
To: Bitterblue Smith, linux-wireless@vger.kernel.org
Cc: Jes Sorensen, art1310@proton.me
Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> Some devices malfunction when connected to a network with 40 MHz channel
> width, because they don't support that.
>
> RTL8188FU, RTL8192FU, and RTL8710BU (RTL8188GU) have a way to signal
> this (and some other capabilities) to the driver. Get this information
> from the hardware and advertise 40 MHz support only when the hardware
> can handle it. We assume the other chips can always handle it.
>
> RTL8710BU needs a different way to retrieve this information, which will
> be implemented some other time.
>
> Fixes: dbf9b7bb0edf ("wifi: rtl8xxxu: Enable 40 MHz width by default")
> Cc: stable@vger.kernel.org
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221394
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
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