Re: [RFC PATCH v4] rtl8xxxu: Improve TX performance of RTL8723BU on rtl8xxxu driver

From: Chris Chiu
Date: Mon Jun 10 2019 - 06:34:03 EST

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On Wed, Jun 5, 2019 at 10:17 AM Chris Chiu <chiu@xxxxxxxxxxxx> wrote:
>
> On Tue, Jun 4, 2019 at 3:21 AM Jes Sorensen <jes.sorensen@xxxxxxxxx> wrote:
> >
> > On 5/31/19 5:12 AM, Chris Chiu wrote:
> > > We have 3 laptops which connect the wifi by the same RTL8723BU.
> > > The PCI VID/PID of the wifi chip is 10EC:B720 which is supported.
> > > They have the same problem with the in-kernel rtl8xxxu driver, the
> > > iperf (as a client to an ethernet-connected server) gets ~1Mbps.
> > > Nevertheless, the signal strength is reported as around -40dBm,
> > > which is quite good. From the wireshark capture, the tx rate for each
> > > data and qos data packet is only 1Mbps. Compare to the Realtek driver
> > > at https://github.com/lwfinger/rtl8723bu, the same iperf test gets
> > > ~12Mbps or better. The signal strength is reported similarly around
> > > -40dBm. That's why we want to improve.
> > >
> > > After reading the source code of the rtl8xxxu driver and Realtek's, the
> > > major difference is that Realtek's driver has a watchdog which will keep
> > > monitoring the signal quality and updating the rate mask just like the
> > > rtl8xxxu_gen2_update_rate_mask() does if signal quality changes.
> > > And this kind of watchdog also exists in rtlwifi driver of some specific
> > > chips, ex rtl8192ee, rtl8188ee, rtl8723ae, rtl8821ae...etc. They have
> > > the same member function named dm_watchdog and will invoke the
> > > corresponding dm_refresh_rate_adaptive_mask to adjust the tx rate
> > > mask.
> > >
> > > With this commit, the tx rate of each data and qos data packet will
> > > be 39Mbps (MCS4) with the 0xF00000 as the tx rate mask. The 20th bit
> > > to 23th bit means MCS4 to MCS7. It means that the firmware still picks
> > > the lowest rate from the rate mask and explains why the tx rate of
> > > data and qos data is always lowest 1Mbps because the default rate mask
> > > passed is always 0xFFFFFFF ranges from the basic CCK rate, OFDM rate,
> > > and MCS rate. However, with Realtek's driver, the tx rate observed from
> > > wireshark under the same condition is almost 65Mbps or 72Mbps.
> > >
> > > I believe the firmware of RTL8723BU may need fix. And I think we
> > > can still bring in the dm_watchdog as rtlwifi to improve from the
> > > driver side. Please leave precious comments for my commits and
> > > suggest what I can do better. Or suggest if there's any better idea
> > > to fix this. Thanks.
> > >
> > > Signed-off-by: Chris Chiu <chiu@xxxxxxxxxxxx>
> >
> > I am really pleased to see you're investigating some of these issues,
> > since I've been pretty swamped and not had time to work on this driver
> > for a long time.
> >
> > The firmware should allow for two rate modes, either firmware handled or
> > controlled by the driver. Ideally we would want the driver to handle it,
> > but I never was able to make that work reliable.
> >
> > This fix should at least improve the situation, and it may explain some
> > of the performance issues with the 8192eu as well?
> >
> > > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> > > index 8828baf26e7b..216f603827a8 100644
> > > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> > > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> > > @@ -1195,6 +1195,44 @@ struct rtl8723bu_c2h {
> > >
> > > struct rtl8xxxu_fileops;
> > >
> > > +/*mlme related.*/
> > > +enum wireless_mode {
> > > + WIRELESS_MODE_UNKNOWN = 0,
> > > + /* Sub-Element */
> > > + WIRELESS_MODE_B = BIT(0),
> > > + WIRELESS_MODE_G = BIT(1),
> > > + WIRELESS_MODE_A = BIT(2),
> > > + WIRELESS_MODE_N_24G = BIT(3),
> > > + WIRELESS_MODE_N_5G = BIT(4),
> > > + WIRELESS_AUTO = BIT(5),
> > > + WIRELESS_MODE_AC = BIT(6),
> > > + WIRELESS_MODE_MAX = 0x7F,
> > > +};
> > > +
> > > +/* from rtlwifi/wifi.h */
> > > +enum ratr_table_mode_new {
> > > + RATEID_IDX_BGN_40M_2SS = 0,
> > > + RATEID_IDX_BGN_40M_1SS = 1,
> > > + RATEID_IDX_BGN_20M_2SS_BN = 2,
> > > + RATEID_IDX_BGN_20M_1SS_BN = 3,
> > > + RATEID_IDX_GN_N2SS = 4,
> > > + RATEID_IDX_GN_N1SS = 5,
> > > + RATEID_IDX_BG = 6,
> > > + RATEID_IDX_G = 7,
> > > + RATEID_IDX_B = 8,
> > > + RATEID_IDX_VHT_2SS = 9,
> > > + RATEID_IDX_VHT_1SS = 10,
> > > + RATEID_IDX_MIX1 = 11,
> > > + RATEID_IDX_MIX2 = 12,
> > > + RATEID_IDX_VHT_3SS = 13,
> > > + RATEID_IDX_BGN_3SS = 14,
> > > +};
> > > +
> > > +#define RTL8XXXU_RATR_STA_INIT 0
> > > +#define RTL8XXXU_RATR_STA_HIGH 1
> > > +#define RTL8XXXU_RATR_STA_MID 2
> > > +#define RTL8XXXU_RATR_STA_LOW 3
> > > +
> >
> > > extern struct rtl8xxxu_fileops rtl8192cu_fops;
> > > extern struct rtl8xxxu_fileops rtl8192eu_fops;
> > > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> > > index 26b674aca125..2071ab9fd001 100644
> > > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> > > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> > > @@ -1645,6 +1645,148 @@ static void rtl8723bu_init_statistics(struct rtl8xxxu_priv *priv)
> > > rtl8xxxu_write32(priv, REG_OFDM0_FA_RSTC, val32);
> > > }
> > >
> > > +static u8 rtl8723b_signal_to_rssi(int signal)
> > > +{
> > > + if (signal < -95)
> > > + signal = -95;
> > > + return (u8)(signal + 95);
> > > +}
> >
> > Could you make this more generic so it can be used by the other sub-drivers?
> >
> Sure. I'll do that.
>
> > > +static void rtl8723b_refresh_rate_mask(struct rtl8xxxu_priv *priv,
> > > + int signal, struct ieee80211_sta *sta)
> > > +{
> > > + struct ieee80211_hw *hw = priv->hw;
> > > + u16 wireless_mode;
> > > + u8 rssi_level, ratr_idx;
> > > + u8 txbw_40mhz;
> > > + u8 rssi, rssi_thresh_high, rssi_thresh_low;
> > > +
> > > + rssi_level = priv->rssi_level;
> > > + rssi = rtl8723b_signal_to_rssi(signal);
> > > + txbw_40mhz = (hw->conf.chandef.width == NL80211_CHAN_WIDTH_40) ? 1 : 0;
> > > +
> > > + switch (rssi_level) {
> > > + case RTL8XXXU_RATR_STA_HIGH:
> > > + rssi_thresh_high = 50;
> > > + rssi_thresh_low = 20;
> > > + break;
> > > + case RTL8XXXU_RATR_STA_MID:
> > > + rssi_thresh_high = 55;
> > > + rssi_thresh_low = 20;
> > > + break;
> > > + case RTL8XXXU_RATR_STA_LOW:
> > > + rssi_thresh_high = 60;
> > > + rssi_thresh_low = 25;
> > > + break;
> > > + default:
> > > + rssi_thresh_high = 50;
> > > + rssi_thresh_low = 20;
> > > + break;
> > > + }
> >
> > Can we make this use defined values with some explanation rather than
> > hard coded values?
> >
>
> I also thought about this. So I refer to the same refresh_rateadaotive_mask
> in rtlwifi/rtl8192se/dm.c, rtlwifi/rtl8723ae/dm.c, and rtl8188ee...etc. They
> don't give a better explanation. And I also don't know if these values can be
> generally applied to other subdrivers or specifically for 8723b series, for
> example, the rtl8192se use different values for the threshold. It maybe due
> to different noise floor for different chip? I'm not sure. I took these values
> from vendor driver and rtl8188ee. I can simply use defined values to replace
> but I have to admit it's hard to find a good explanation.
>
> > > + if (rssi > rssi_thresh_high)
> > > + rssi_level = RTL8XXXU_RATR_STA_HIGH;
> > > + else if (rssi > rssi_thresh_low)
> > > + rssi_level = RTL8XXXU_RATR_STA_MID;
> > > + else
> > > + rssi_level = RTL8XXXU_RATR_STA_LOW;
> > > +
> > > + if (rssi_level != priv->rssi_level) {
> > > + int sgi = 0;
> > > + u32 rate_bitmap = 0;
> > > +
> > > + rcu_read_lock();
> > > + rate_bitmap = (sta->supp_rates[0] & 0xfff) |
> > > + (sta->ht_cap.mcs.rx_mask[0] << 12) |
> > > + (sta->ht_cap.mcs.rx_mask[1] << 20);
> > > + if (sta->ht_cap.cap &
> > > + (IEEE80211_HT_CAP_SGI_40 | IEEE80211_HT_CAP_SGI_20))
> > > + sgi = 1;
> > > + rcu_read_unlock();
> > > +
> > > + wireless_mode = rtl8xxxu_wireless_mode(hw, sta);
> > > + switch (wireless_mode) {
> > > + case WIRELESS_MODE_B:
> > > + ratr_idx = RATEID_IDX_B;
> > > + if (rate_bitmap & 0x0000000c)
> > > + rate_bitmap &= 0x0000000d;
> > > + else
> > > + rate_bitmap &= 0x0000000f;
> > > + break;
> > > + case WIRELESS_MODE_A:
> > > + case WIRELESS_MODE_G:
> > > + ratr_idx = RATEID_IDX_G;
> > > + if (rssi_level == RTL8XXXU_RATR_STA_HIGH)
> > > + rate_bitmap &= 0x00000f00;
> > > + else
> > > + rate_bitmap &= 0x00000ff0;
> > > + break;
> > > + case (WIRELESS_MODE_B | WIRELESS_MODE_G):
> > > + ratr_idx = RATEID_IDX_BG;
> > > + if (rssi_level == RTL8XXXU_RATR_STA_HIGH)
> > > + rate_bitmap &= 0x00000f00;
> > > + else if (rssi_level == RTL8XXXU_RATR_STA_MID)
> > > + rate_bitmap &= 0x00000ff0;
> > > + else
> > > + rate_bitmap &= 0x00000ff5;
> > > + break;
> >
> > It would be nice as well to get all these masks into generic names.
> >
>
> I also take these mask values from the update_hal_rate_mask of the
> vendor driver and other realtek drivers under rtlwifi. I thought about to
> define the lower 12 bits like RTL8XXXU_BG_RATE_MASK, 13~20 bits
> as RTL8XXXU_MCS0_7_RATE_MASK. But it's still hard to express
> all the combinations here. So I just leave it as it is. I can try to add
> explanations for the rate mapping of each bit. It would be a lot easier.
>
> > > + case WIRELESS_MODE_N_24G:
> > > + case WIRELESS_MODE_N_5G:
> > > + case (WIRELESS_MODE_G | WIRELESS_MODE_N_24G):
> > > + case (WIRELESS_MODE_A | WIRELESS_MODE_N_5G):
> > > + if (priv->tx_paths == 2 && priv->rx_paths == 2)
> > > + ratr_idx = RATEID_IDX_GN_N2SS;
> > > + else
> > > + ratr_idx = RATEID_IDX_GN_N1SS;
> > > + case (WIRELESS_MODE_B | WIRELESS_MODE_G | WIRELESS_MODE_N_24G):
> > > + case (WIRELESS_MODE_B | WIRELESS_MODE_N_24G):
> > > + if (txbw_40mhz) {
> > > + if (priv->tx_paths == 2 && priv->rx_paths == 2)
> > > + ratr_idx = RATEID_IDX_BGN_40M_2SS;
> > > + else
> > > + ratr_idx = RATEID_IDX_BGN_40M_1SS;
> > > + } else {
> > > + if (priv->tx_paths == 2 && priv->rx_paths == 2)
> > > + ratr_idx = RATEID_IDX_BGN_20M_2SS_BN;
> > > + else
> > > + ratr_idx = RATEID_IDX_BGN_20M_1SS_BN;
> > > + }
> > > +
> > > + if (priv->tx_paths == 2 && priv->rx_paths == 2) {
> > > + if (rssi_level == RTL8XXXU_RATR_STA_HIGH) {
> > > + rate_bitmap &= 0x0f8f0000;
> > > + } else if (rssi_level == RTL8XXXU_RATR_STA_MID) {
> > > + rate_bitmap &= 0x0f8ff000;
> > > + } else {
> > > + if (txbw_40mhz)
> > > + rate_bitmap &= 0x0f8ff015;
> > > + else
> > > + rate_bitmap &= 0x0f8ff005;
> > > + }
> > > + } else {
> > > + if (rssi_level == RTL8XXXU_RATR_STA_HIGH) {
> > > + rate_bitmap &= 0x000f0000;
> > > + } else if (rssi_level == RTL8XXXU_RATR_STA_MID) {
> > > + rate_bitmap &= 0x000ff000;
> > > + } else {
> > > + if (txbw_40mhz)
> > > + rate_bitmap &= 0x000ff015;
> > > + else
> > > + rate_bitmap &= 0x000ff005;
> > > + }
> > > + }
> > > + break;
> > > + default:
> > > + ratr_idx = RATEID_IDX_BGN_40M_2SS;
> > > + rate_bitmap &= 0x0fffffff;
> > > + break;
> > > + }
> > > +
> > > + priv->rssi_level = rssi_level;
> > > + priv->fops->update_rate_mask(priv, rate_bitmap, ratr_idx, sgi);
> > > + }
> > > +}
> > > +
> >
> > In general I think all of this should be fairly generic and the other
> > subdrivers should be able to benefit from it?
> >
> >
> I agree. Mabe separates the rssi level judgement function to be chip specific,
> and move the whole refresh_rate_mask thing generic?
>
> > > struct rtl8xxxu_fileops rtl8723bu_fops = {
> > > .parse_efuse = rtl8723bu_parse_efuse,
> > > .load_firmware = rtl8723bu_load_firmware,
> > > @@ -1665,6 +1807,7 @@ struct rtl8xxxu_fileops rtl8723bu_fops = {
> > > .usb_quirks = rtl8xxxu_gen2_usb_quirks,
> > > .set_tx_power = rtl8723b_set_tx_power,
> > > .update_rate_mask = rtl8xxxu_gen2_update_rate_mask,
> > > + .refresh_rate_mask = rtl8723b_refresh_rate_mask,
> > > .report_connect = rtl8xxxu_gen2_report_connect,
> > > .fill_txdesc = rtl8xxxu_fill_txdesc_v2,
> > > .writeN_block_size = 1024,
> > > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > > index 039e5ca9d2e4..be322402ca01 100644
> > > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > > @@ -4311,7 +4311,8 @@ static void rtl8xxxu_sw_scan_complete(struct ieee80211_hw *hw,
> > > rtl8xxxu_write8(priv, REG_BEACON_CTRL, val8);
> > > }
> > >
> > > -void rtl8xxxu_update_rate_mask(struct rtl8xxxu_priv *priv, u32 ramask, int sgi)
> > > +void rtl8xxxu_update_rate_mask(struct rtl8xxxu_priv *priv,
> > > + u32 ramask, u8 rateid, int sgi)
> > > {
> > > struct h2c_cmd h2c;
> > >
> > > @@ -4331,7 +4332,7 @@ void rtl8xxxu_update_rate_mask(struct rtl8xxxu_priv *priv, u32 ramask, int sgi)
> > > }
> > >
> > > void rtl8xxxu_gen2_update_rate_mask(struct rtl8xxxu_priv *priv,
> > > - u32 ramask, int sgi)
> > > + u32 ramask, u8 rateid, int sgi)
> > > {
> > > struct h2c_cmd h2c;
> > > u8 bw = 0;
> > > @@ -4345,7 +4346,7 @@ void rtl8xxxu_gen2_update_rate_mask(struct rtl8xxxu_priv *priv,
> > > h2c.b_macid_cfg.ramask3 = (ramask >> 24) & 0xff;
> > >
> > > h2c.ramask.arg = 0x80;
> > > - h2c.b_macid_cfg.data1 = 0;
> > > + h2c.b_macid_cfg.data1 = rateid;
> > > if (sgi)
> > > h2c.b_macid_cfg.data1 |= BIT(7);
> > >
> > > @@ -4485,6 +4486,40 @@ static void rtl8xxxu_set_basic_rates(struct rtl8xxxu_priv *priv, u32 rate_cfg)
> > > rtl8xxxu_write8(priv, REG_INIRTS_RATE_SEL, rate_idx);
> > > }
> > >
> > > +u16
> > > +rtl8xxxu_wireless_mode(struct ieee80211_hw *hw, struct ieee80211_sta *sta)
> > > +{
> > > + u16 network_type = WIRELESS_MODE_UNKNOWN;
> > > + u32 rate_mask;
> > > +
> > > + rate_mask = (sta->supp_rates[0] & 0xfff) |
> > > + (sta->ht_cap.mcs.rx_mask[0] << 12) |
> > > + (sta->ht_cap.mcs.rx_mask[0] << 20);
> > > +
> > > + if (hw->conf.chandef.chan->band == NL80211_BAND_5GHZ) {
> > > + if (sta->vht_cap.vht_supported)
> > > + network_type = WIRELESS_MODE_AC;
> > > + else if (sta->ht_cap.ht_supported)
> > > + network_type = WIRELESS_MODE_N_5G;
> > > +
> > > + network_type |= WIRELESS_MODE_A;
> > > + } else {
> > > + if (sta->vht_cap.vht_supported)
> > > + network_type = WIRELESS_MODE_AC;
> > > + else if (sta->ht_cap.ht_supported)
> > > + network_type = WIRELESS_MODE_N_24G;
> > > +
> > > + if (sta->supp_rates[0] <= 0xf)
> > > + network_type |= WIRELESS_MODE_B;
> > > + else if (sta->supp_rates[0] & 0xf)
> > > + network_type |= (WIRELESS_MODE_B | WIRELESS_MODE_G);
> > > + else
> > > + network_type |= WIRELESS_MODE_G;
> > > + }
> > > +
> > > + return network_type;
> > > +}
> >
> > I always hated the wireless_mode nonsense in the realtek driver, but
> > maybe we cannot avoid it :(
> >
> > Cheers,
> > Jes

Jes, look forward to any comments or suggestions from you. I would re-write a
patch with generic refresh_rate_mask for all rtl8xxxu series chips in
short time.

Chris

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