[PATCH rtw-next 0/5] wifi: rtl8xxxu: 40 MHz fixes

[PATCH rtw-next 0/5] wifi: rtl8xxxu: 40 MHz fixes

[Bitterblue Smith]

All the chips should work with 40 MHz width now.

Bitterblue Smith (5):
  wifi: rtl8xxxu: Fix HT40 channel config for RTL8192CU, RTL8723AU
  wifi: rtl8xxxu: Make RTL8192CU, RTL8723AU TX with 40 MHz width
  wifi: rtl8xxxu: Fix the 40 MHz subchannel for RTL8192EU, RTL8723BU
  wifi: rtl8xxxu: Fix RX channel width reported by RTL8192FU
  wifi: rtl8xxxu: Enable 40 MHz width by default

 drivers/net/wireless/realtek/rtl8xxxu/core.c | 52 ++++++++++++--------
 1 file changed, 31 insertions(+), 21 deletions(-)

-- 
2.51.1

[PATCH rtw-next 1/5] wifi: rtl8xxxu: Fix HT40 channel config for RTL8192CU, RTL8723AU

[Bitterblue Smith]

Flip the response rate subchannel. It was backwards, causing low
speeds when using 40 MHz channel width. "iw dev ... station dump"
showed a low RX rate, 11M or less.

Also fix the channel width field of RF6052_REG_MODE_AG.

Tested only with RTL8192CU, but these settings are identical for
RTL8723AU.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
 drivers/net/wireless/realtek/rtl8xxxu/core.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c b/drivers/net/wireless/realtek/rtl8xxxu/core.c
index d82cb7714314..be8ee6c30034 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
@@ -1252,7 +1252,7 @@ void rtl8xxxu_gen1_config_channel(struct ieee80211_hw *hw)
 		opmode &= ~BW_OPMODE_20MHZ;
 		rtl8xxxu_write8(priv, REG_BW_OPMODE, opmode);
 		rsr &= ~RSR_RSC_BANDWIDTH_40M;
-		if (sec_ch_above)
+		if (!sec_ch_above)
 			rsr |= RSR_RSC_UPPER_SUB_CHANNEL;
 		else
 			rsr |= RSR_RSC_LOWER_SUB_CHANNEL;
@@ -1321,9 +1321,8 @@ void rtl8xxxu_gen1_config_channel(struct ieee80211_hw *hw)
 
 	for (i = RF_A; i < priv->rf_paths; i++) {
 		val32 = rtl8xxxu_read_rfreg(priv, i, RF6052_REG_MODE_AG);
-		if (hw->conf.chandef.width == NL80211_CHAN_WIDTH_40)
-			val32 &= ~MODE_AG_CHANNEL_20MHZ;
-		else
+		val32 &= ~MODE_AG_BW_MASK;
+		if (hw->conf.chandef.width != NL80211_CHAN_WIDTH_40)
 			val32 |= MODE_AG_CHANNEL_20MHZ;
 		rtl8xxxu_write_rfreg(priv, i, RF6052_REG_MODE_AG, val32);
 	}
-- 
2.51.1

RE: [PATCH rtw-next 1/5] wifi: rtl8xxxu: Fix HT40 channel config for RTL8192CU, RTL8723AU

[Ping-Ke Shih]

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> Flip the response rate subchannel. It was backwards, causing low
> speeds when using 40 MHz channel width. "iw dev ... station dump"
> showed a low RX rate, 11M or less.
> 
> Also fix the channel width field of RF6052_REG_MODE_AG.
> 
> Tested only with RTL8192CU, but these settings are identical for
> RTL8723AU.
> 
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>

Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>

[PATCH rtw-next 2/5] wifi: rtl8xxxu: Make RTL8192CU, RTL8723AU TX with 40 MHz width

[Bitterblue Smith]

Set the required fields in the TX descriptor to allow these chips to
transmit with 40 MHz channel width when the access point supports it.

Tested only with RTL8192CU, but these settings are identical for
RTL8723AU.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
 drivers/net/wireless/realtek/rtl8xxxu/core.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c b/drivers/net/wireless/realtek/rtl8xxxu/core.c
index be8ee6c30034..7700e4074dc3 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
@@ -5221,9 +5221,19 @@ rtl8xxxu_fill_txdesc_v1(struct ieee80211_hw *hw, struct ieee80211_hdr *hdr,
 		tx_desc->txdw5 |= cpu_to_le32(TXDESC32_RETRY_LIMIT_ENABLE);
 	}
 
-	if (ieee80211_is_data_qos(hdr->frame_control))
+	if (ieee80211_is_data_qos(hdr->frame_control)) {
 		tx_desc->txdw4 |= cpu_to_le32(TXDESC32_QOS);
 
+		if (conf_is_ht40(&hw->conf)) {
+			tx_desc->txdw4 |= cpu_to_le32(TXDESC_DATA_BW);
+
+			if (conf_is_ht40_minus(&hw->conf))
+				tx_desc->txdw4 |= cpu_to_le32(TXDESC_PRIME_CH_OFF_UPPER);
+			else
+				tx_desc->txdw4 |= cpu_to_le32(TXDESC_PRIME_CH_OFF_LOWER);
+		}
+	}
+
 	if (short_preamble)
 		tx_desc->txdw4 |= cpu_to_le32(TXDESC32_SHORT_PREAMBLE);
 
-- 
2.51.1

RE: [PATCH rtw-next 2/5] wifi: rtl8xxxu: Make RTL8192CU, RTL8723AU TX with 40 MHz width

[Ping-Ke Shih]

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> Set the required fields in the TX descriptor to allow these chips to
> transmit with 40 MHz channel width when the access point supports it.
> 
> Tested only with RTL8192CU, but these settings are identical for
> RTL8723AU.
> 
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>

Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>

[PATCH rtw-next 3/5] wifi: rtl8xxxu: Fix the 40 MHz subchannel for RTL8192EU, RTL8723BU

[Bitterblue Smith]

rtl8xxxu_gen2_config_channel() was missing the subchannel setting.
This function is used by RTL8192EU and RTL8723BU.

This change seems to make no difference in my testing on channel 13
with either chip.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
 drivers/net/wireless/realtek/rtl8xxxu/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c b/drivers/net/wireless/realtek/rtl8xxxu/core.c
index 7700e4074dc3..739456640ca8 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
@@ -1373,9 +1373,11 @@ void rtl8xxxu_gen2_config_channel(struct ieee80211_hw *hw)
 		    hw->conf.chandef.chan->center_freq) {
 			sec_ch_above = 1;
 			channel += 2;
+			subchannel = 2;
 		} else {
 			sec_ch_above = 0;
 			channel -= 2;
+			subchannel = 1;
 		}
 
 		val32 = rtl8xxxu_read32(priv, REG_FPGA0_RF_MODE);
-- 
2.51.1

RE: [PATCH rtw-next 3/5] wifi: rtl8xxxu: Fix the 40 MHz subchannel for RTL8192EU, RTL8723BU

[Ping-Ke Shih]

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> rtl8xxxu_gen2_config_channel() was missing the subchannel setting.
> This function is used by RTL8192EU and RTL8723BU.
> 
> This change seems to make no difference in my testing on channel 13
> with either chip.
> 
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>

Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>


> ---
>  drivers/net/wireless/realtek/rtl8xxxu/core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c
> b/drivers/net/wireless/realtek/rtl8xxxu/core.c
> index 7700e4074dc3..739456640ca8 100644
> --- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
> +++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
> @@ -1373,9 +1373,11 @@ void rtl8xxxu_gen2_config_channel(struct ieee80211_hw *hw)
>                     hw->conf.chandef.chan->center_freq) {
>                         sec_ch_above = 1;
>                         channel += 2;
> +                       subchannel = 2;

(For record)
By vendor driver, 'subchannel = 2' means primary channel at lower 20MHz.

>                 } else {
>                         sec_ch_above = 0;
>                         channel -= 2;
> +                       subchannel = 1;
>                 }
> 
>                 val32 = rtl8xxxu_read32(priv, REG_FPGA0_RF_MODE);
> --
> 2.51.1

[PATCH rtw-next 4/5] wifi: rtl8xxxu: Fix RX channel width reported by RTL8192FU

[Bitterblue Smith]

The other chips report the RX channel width in the RX descriptor,
but this one doesn't.

Get the RX channel width from the PHY status.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
 drivers/net/wireless/realtek/rtl8xxxu/core.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c b/drivers/net/wireless/realtek/rtl8xxxu/core.c
index 739456640ca8..668018229f7c 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
@@ -5701,7 +5701,7 @@ static void jaguar2_rx_parse_phystats_type1(struct rtl8xxxu_priv *priv,
 			 !rtl8xxxu_is_sta_sta(priv) &&
 			 (rtl8xxxu_is_packet_match_bssid(priv, hdr, 0) ||
 			  rtl8xxxu_is_packet_match_bssid(priv, hdr, 1));
-	u8 pwdb_max = 0;
+	u8 pwdb_max = 0, rxsc;
 	int rx_path;
 
 	if (parse_cfo) {
@@ -5716,6 +5716,16 @@ static void jaguar2_rx_parse_phystats_type1(struct rtl8xxxu_priv *priv,
 		pwdb_max = max(pwdb_max, phy_stats1->pwdb[rx_path]);
 
 	rx_status->signal = pwdb_max - 110;
+
+	if (rxmcs > DESC_RATE_11M && rxmcs < DESC_RATE_MCS0)
+		rxsc = phy_stats1->l_rxsc;
+	else
+		rxsc = phy_stats1->ht_rxsc;
+
+	if (phy_stats1->rf_mode == 0 || rxsc == 1 || rxsc == 2)
+		rx_status->bw = RATE_INFO_BW_20;
+	else
+		rx_status->bw = RATE_INFO_BW_40;
 }
 
 static void jaguar2_rx_parse_phystats_type2(struct rtl8xxxu_priv *priv,
-- 
2.51.1

RE: [PATCH rtw-next 4/5] wifi: rtl8xxxu: Fix RX channel width reported by RTL8192FU

[Ping-Ke Shih]

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> The other chips report the RX channel width in the RX descriptor,
> but this one doesn't.
> 
> Get the RX channel width from the PHY status.
> 
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>

Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>


> ---
>  drivers/net/wireless/realtek/rtl8xxxu/core.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c
> b/drivers/net/wireless/realtek/rtl8xxxu/core.c
> index 739456640ca8..668018229f7c 100644
> --- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
> +++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
> @@ -5701,7 +5701,7 @@ static void jaguar2_rx_parse_phystats_type1(struct rtl8xxxu_priv *priv,
>                          !rtl8xxxu_is_sta_sta(priv) &&
>                          (rtl8xxxu_is_packet_match_bssid(priv, hdr, 0) ||
>                           rtl8xxxu_is_packet_match_bssid(priv, hdr, 1));
> -       u8 pwdb_max = 0;
> +       u8 pwdb_max = 0, rxsc;
>         int rx_path;
> 
>         if (parse_cfo) {
> @@ -5716,6 +5716,16 @@ static void jaguar2_rx_parse_phystats_type1(struct rtl8xxxu_priv *priv,
>                 pwdb_max = max(pwdb_max, phy_stats1->pwdb[rx_path]);
> 
>         rx_status->signal = pwdb_max - 110;
> +
> +       if (rxmcs > DESC_RATE_11M && rxmcs < DESC_RATE_MCS0)

Nit: would it be clear that ' if (rxmcs >= DESC_RATE_6M && rxmcs <= DESC_RATE_54M)' ?

> +               rxsc = phy_stats1->l_rxsc;
> +       else
> +               rxsc = phy_stats1->ht_rxsc;
> +
> +       if (phy_stats1->rf_mode == 0 || rxsc == 1 || rxsc == 2)
> +               rx_status->bw = RATE_INFO_BW_20;
> +       else
> +               rx_status->bw = RATE_INFO_BW_40;
>  }
> 
>  static void jaguar2_rx_parse_phystats_type2(struct rtl8xxxu_priv *priv,
> --
> 2.51.1

RE: [PATCH rtw-next 4/5] wifi: rtl8xxxu: Fix RX channel width reported by RTL8192FU

[Ping-Ke Shih]

Hi Bitterblue,

> > +
> > +       if (rxmcs > DESC_RATE_11M && rxmcs < DESC_RATE_MCS0)
> 
> Nit: would it be clear that ' if (rxmcs >= DESC_RATE_6M && rxmcs <= DESC_RATE_54M)' ?
> 

Please let me know your thought about this nit. 

Re: [PATCH rtw-next 4/5] wifi: rtl8xxxu: Fix RX channel width reported by RTL8192FU

[Bitterblue Smith]

On 18/11/2025 05:02, Ping-Ke Shih wrote:
> Hi Bitterblue,
> 
>>> +
>>> +       if (rxmcs > DESC_RATE_11M && rxmcs < DESC_RATE_MCS0)
>>
>> Nit: would it be clear that ' if (rxmcs >= DESC_RATE_6M && rxmcs <= DESC_RATE_54M)' ?
>>
> 
> Please let me know your thought about this nit. 
> 

Yes, that's better. Now I remember this came up before.

RE: [PATCH rtw-next 4/5] wifi: rtl8xxxu: Fix RX channel width reported by RTL8192FU

[Ping-Ke Shih]

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> On 18/11/2025 05:02, Ping-Ke Shih wrote:
> > Hi Bitterblue,
> >
> >>> +
> >>> +       if (rxmcs > DESC_RATE_11M && rxmcs < DESC_RATE_MCS0)
> >>
> >> Nit: would it be clear that ' if (rxmcs >= DESC_RATE_6M && rxmcs <= DESC_RATE_54M)' ?
> >>
> >
> > Please let me know your thought about this nit.
> >
> 
> Yes, that's better. Now I remember this came up before.

I'll wait for your v2 then.

[PATCH rtw-next 5/5] wifi: rtl8xxxu: Enable 40 MHz width by default

[Bitterblue Smith]

40 MHz support is hidden behind the ht40_2g module parameter with
this comment:

/*
 * Some APs will negotiate HT20_40 in a noisy environment leading
 * to miserable performance. Rather than defaulting to this, only
 * enable it if explicitly requested at module load time.
 */

This parameter was added in commit 26f1fad29ad9 ("New driver:
rtl8xxxu (mac80211)"). Back then rtl8xxxu only supported RTL8723AU
and the RTL8192CU family. It's entirely possible the miserable
performance was due to mistakes in the channel switching function,
which were fixed in a previous patch.

Delete the ht40_2g module parameter. If someone still needs to
disable 40 MHz support, cfg80211 has the module parameter
cfg80211_disable_40mhz_24ghz. That works too.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
 drivers/net/wireless/realtek/rtl8xxxu/core.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c b/drivers/net/wireless/realtek/rtl8xxxu/core.c
index 668018229f7c..12935b196520 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
@@ -20,7 +20,6 @@
 #define DRIVER_NAME "rtl8xxxu"
 
 int rtl8xxxu_debug;
-static bool rtl8xxxu_ht40_2g;
 static bool rtl8xxxu_dma_aggregation;
 static int rtl8xxxu_dma_agg_timeout = -1;
 static int rtl8xxxu_dma_agg_pages = -1;
@@ -45,8 +44,6 @@ MODULE_FIRMWARE("rtlwifi/rtl8192fufw.bin");
 
 module_param_named(debug, rtl8xxxu_debug, int, 0600);
 MODULE_PARM_DESC(debug, "Set debug mask");
-module_param_named(ht40_2g, rtl8xxxu_ht40_2g, bool, 0600);
-MODULE_PARM_DESC(ht40_2g, "Enable HT40 support on the 2.4GHz band");
 module_param_named(dma_aggregation, rtl8xxxu_dma_aggregation, bool, 0600);
 MODULE_PARM_DESC(dma_aggregation, "Enable DMA packet aggregation");
 module_param_named(dma_agg_timeout, rtl8xxxu_dma_agg_timeout, int, 0600);
@@ -4896,8 +4893,7 @@ rtl8xxxu_bss_info_changed(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 				sgi = 1;
 
 			highest_rate = fls(ramask) - 1;
-			if (rtl8xxxu_ht40_2g &&
-			    (sta->deflink.ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40))
+			if (sta->deflink.ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40)
 				bw = RATE_INFO_BW_40;
 			else
 				bw = RATE_INFO_BW_20;
@@ -7851,7 +7847,8 @@ 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;
+	sband->ht_cap.cap = IEEE80211_HT_CAP_SGI_20 | IEEE80211_HT_CAP_SGI_40 |
+			    IEEE80211_HT_CAP_SUP_WIDTH_20_40;
 	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;
@@ -7860,15 +7857,7 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
 		sband->ht_cap.cap |= IEEE80211_HT_CAP_SGI_40;
 	}
 	sband->ht_cap.mcs.tx_params = IEEE80211_HT_MCS_TX_DEFINED;
-	/*
-	 * Some APs will negotiate HT20_40 in a noisy environment leading
-	 * to miserable performance. Rather than defaulting to this, only
-	 * enable it if explicitly requested at module load time.
-	 */
-	if (rtl8xxxu_ht40_2g) {
-		dev_info(&udev->dev, "Enabling HT_20_40 on the 2.4GHz band\n");
-		sband->ht_cap.cap |= IEEE80211_HT_CAP_SUP_WIDTH_20_40;
-	}
+
 	hw->wiphy->bands[NL80211_BAND_2GHZ] = sband;
 
 	hw->wiphy->rts_threshold = 2347;
-- 
2.51.1

RE: [PATCH rtw-next 5/5] wifi: rtl8xxxu: Enable 40 MHz width by default

[Ping-Ke Shih]

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> 40 MHz support is hidden behind the ht40_2g module parameter with
> this comment:
> 
> /*
>  * Some APs will negotiate HT20_40 in a noisy environment leading
>  * to miserable performance. Rather than defaulting to this, only
>  * enable it if explicitly requested at module load time.
>  */
> 
> This parameter was added in commit 26f1fad29ad9 ("New driver:
> rtl8xxxu (mac80211)"). Back then rtl8xxxu only supported RTL8723AU
> and the RTL8192CU family. It's entirely possible the miserable
> performance was due to mistakes in the channel switching function,
> which were fixed in a previous patch.
> 
> Delete the ht40_2g module parameter. If someone still needs to
> disable 40 MHz support, cfg80211 has the module parameter
> cfg80211_disable_40mhz_24ghz. That works too.
> 
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>

Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>