Re: [RFC PATCH 2/2] rtl8xxxu: Add watchdog to update rate mask by signal strength

From: Chris Chiu
Date: Thu May 09 2019 - 05:19:03 EST

On Thu, May 9, 2019 at 4:11 PM Daniel Drake <drake@xxxxxxxxxxxx> wrote:
>
> Hi Chris,
>
> Great work on finding this!
>
> On Fri, May 3, 2019 at 3:22 PM Chris Chiu <chiu@xxxxxxxxxxxx> wrote:
> > Introduce watchdog to monitor signal then update the rate mask
> > accordingly. The rate mask update logic comes from the rtlwifi
> > refresh_rate_adaptive_mask() from different chips.
>
> You should expand your commit message here to summarise the key points
> in the cover letter. Specifically that matching this aspect of the
> vendor driver results in a significant TX performance increase which
> was previously stuck at 1mbps.
>
> > ---
> > .../net/wireless/realtek/rtl8xxxu/rtl8xxxu.h | 8 +
> > .../realtek/rtl8xxxu/rtl8xxxu_8723b.c | 151 ++++++++++++++++++
> > .../wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 38 +++++
> > 3 files changed, 197 insertions(+)
> >
> > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> > index 771f58aa7cae..f97271951053 100644
> > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
> > @@ -1239,6 +1239,11 @@ struct rtl8xxxu_rate_adaptive {
> > u8 rssi_level; /* INIT, HIGH, MIDDLE, LOW */
> > } __packed;
> >
> > +struct rtl8xxxu_watchdog {
> > + struct ieee80211_vif *vif;
> > + struct delayed_work ra_wq;
> > +};
>
> Having to store the vif address under the device-specific private
> structure may be a layering violation, but I'm not fully grasping how
> all this fits together. Can anyone from linux-wireless help?
>
> The existing rtl8xxxu_add_interface() code appears to allow multiple
> STA interfaces to be added. Does that imply that the hardware should
> support connecting to multiple APs on different channels? I'm pretty
> sure the hardware doesn't support that; if so we could do something
> similar to ar5523.c where it only allows a single vif, and can easily
> store that pointer in the device-specific structure.
>
> Or if there's a valid reason to support multiple vifs, then we need to
> figure out how to implement this watchdog. As shown below, the
> watchdog needs to know the supported rate info of the AP you are
> connected to, and the RSSI, and that comes from a specific vif. If
> multiple vifs are present, how would we know which one to choose for
> this rate adjustment?
>

I need the vif because there's seems no easy way to get RSSI. Please
suggest if there's any better idea for this. I believe multiple vifs is for AP
mode (with more than 1 virtual AP/SSIDs) and the Station+AP coexist
mode. But the rtl8xxxu driver basically supports only Station mode. So
the vif helps get the RSSI. Or I will need to record the RSSI in
rtl8xxxu_rx_parse_phystats() and store in rtl8xxxu_priv. That's a little
nasty. Maybe someone can point out how to retrieve the RSSI from
specific register or which part of code in rtlwifi I can use to get the
undecorated signal strength.

> > struct rtl8xxxu_priv {
> > struct ieee80211_hw *hw;
> > struct usb_device *udev;
> > @@ -1344,6 +1349,7 @@ struct rtl8xxxu_priv {
> > u8 no_pape:1;
> > u8 int_buf[USB_INTR_CONTENT_LENGTH];
> > struct rtl8xxxu_rate_adaptive ra_info;
> > + struct rtl8xxxu_watchdog watchdog;
> > };
> >
> > struct rtl8xxxu_rx_urb {
> > @@ -1380,6 +1386,8 @@ struct rtl8xxxu_fileops {
> > bool ht40);
> > void (*update_rate_mask) (struct rtl8xxxu_priv *priv,
> > u32 ramask, int sgi);
> > + void (*refresh_rate_mask) (struct rtl8xxxu_priv *priv, int signal,
> > + struct ieee80211_sta *sta);
> > void (*report_connect) (struct rtl8xxxu_priv *priv,
> > u8 macid, bool connect);
> > void (*fill_txdesc) (struct ieee80211_hw *hw, struct ieee80211_hdr *hdr,
> > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> > index 26b674aca125..92c35afecae0 100644
> > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> > @@ -1645,6 +1645,156 @@ 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);
> > +}
> > +
> > +static void rtl8723b_refresh_rate_mask(struct rtl8xxxu_priv *priv,
> > + int signal, struct ieee80211_sta *sta)
> > +{
> > + struct rtl8xxxu_rate_adaptive *ra;
> > + struct ieee80211_hw *hw = priv->hw;
> > + u16 wireless_mode;
> > + u8 rssi_level, ratr_index;
> > + u8 txbw_40mhz;
> > + u8 rssi, rssi_thresh_high, rssi_thresh_low;
> > +
> > + ra = &priv->ra_info;
> > + wireless_mode = ra->wireless_mode;
> > + rssi_level = ra->rssi_level;
> > + rssi = rtl8723b_signal_to_rssi(signal);
> > + ratr_index = ra->ratr_index;
> > + 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;
> > + }
> > +
> > + 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 != ra->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();
> > +
> > + switch (wireless_mode) {
> > + case WIRELESS_MODE_B:
> > + ratr_index = RATEID_IDX_B;
> > + if (rate_bitmap & 0x0000000c)
> > + rate_bitmap &= 0x0000000d;
> > + else
> > + rate_bitmap &= 0x0000000f;
> > + break;
> > + case WIRELESS_MODE_A:
> > + case WIRELESS_MODE_G:
> > + ratr_index = 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_index = 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;
> > + 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_index = RATEID_IDX_GN_N2SS;
> > + else
> > + ratr_index = 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_index = RATEID_IDX_BGN_40M_2SS;
> > + else
> > + ratr_index = RATEID_IDX_BGN_40M_1SS;
> > + }
> > + else {
> > + if (priv->tx_paths == 2 && priv->rx_paths == 2)
> > + ratr_index = RATEID_IDX_BGN_20M_2SS_BN;
> > + else
> > + ratr_index = 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_index = RATEID_IDX_BGN_40M_2SS;
> > + rate_bitmap &= 0x0fffffff;
> > + break;
> > + }
> > +
> > + ra->ratr_index = ratr_index;
> > + ra->rssi_level = rssi_level;
> > + priv->fops->update_rate_mask(priv, rate_bitmap, sgi);
> > + }
> > +
> > + return;
> > +}
> > +
> > struct rtl8xxxu_fileops rtl8723bu_fops = {
> > .parse_efuse = rtl8723bu_parse_efuse,
> > .load_firmware = rtl8723bu_load_firmware,
> > @@ -1665,6 +1815,7 @@ 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 360e9bd837e5..8db479986e97 100644
> > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > @@ -4565,6 +4565,7 @@ rtl8xxxu_bss_info_changed(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
> > sgi = 1;
> > rcu_read_unlock();
> >
> > + priv->watchdog.vif = vif;
> > ra = &priv->ra_info;
> > ra->wireless_mode = rtl8xxxu_wireless_mode(hw, sta);
> > ra->ratr_index = RATEID_IDX_BGN_40M_2SS;
> > @@ -5822,6 +5823,38 @@ rtl8xxxu_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
> > return 0;
> > }
> >
> > +static void rtl8xxxu_watchdog_callback(struct work_struct *work)
> > +{
> > + struct ieee80211_vif *vif;
> > + struct rtl8xxxu_watchdog *wdog;
> > + struct rtl8xxxu_priv *priv;
> > +
> > + wdog = container_of(work, struct rtl8xxxu_watchdog, ra_wq.work);
> > + priv = container_of(wdog, struct rtl8xxxu_priv, watchdog);
> > + vif = wdog->vif;
> > +
> > + if (vif) {
> > + int signal;
> > + struct ieee80211_sta *sta;
> > +
> > + rcu_read_lock();
>
> Can you explain the lock/unlock here?
>

Actually it may not be mandatory because the sta_info_get_bss()
will do this inside ieee80211_find_sta().

> > + sta = ieee80211_find_sta(vif, vif->bss_conf.bssid);
> > + if (!sta) {
> > + struct device *dev = &priv->udev->dev;
> > + dev_info(dev, "%s: no sta found\n", __func__);
>
> Does this result in a kernel log message every 2 seconds when the wifi
> interface is not associated to an AP?

Yes. It prints every 2 seconds if not associated.

>
> > + rcu_read_unlock();
> > + return;
> > + }
> > + rcu_read_unlock();
> > +
> > + signal = ieee80211_ave_rssi(vif);
> > + if (priv->fops->refresh_rate_mask)
> > + priv->fops->refresh_rate_mask(priv, signal, sta);
> > + }
> > +
> > + schedule_delayed_work(&priv->watchdog.ra_wq, 2 * HZ);
> > +}
> > +
> > static int rtl8xxxu_start(struct ieee80211_hw *hw)
> > {
> > struct rtl8xxxu_priv *priv = hw->priv;
> > @@ -5878,6 +5911,8 @@ static int rtl8xxxu_start(struct ieee80211_hw *hw)
> >
> > ret = rtl8xxxu_submit_rx_urb(priv, rx_urb);
> > }
> > +
> > + schedule_delayed_work(&priv->watchdog.ra_wq, 2* HZ);
> > exit:
> > /*
> > * Accept all data and mgmt frames
> > @@ -6101,6 +6136,7 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
> > INIT_LIST_HEAD(&priv->rx_urb_pending_list);
> > spin_lock_init(&priv->rx_urb_lock);
> > INIT_WORK(&priv->rx_urb_wq, rtl8xxxu_rx_urb_work);
> > + INIT_DELAYED_WORK(&priv->watchdog.ra_wq, rtl8xxxu_watchdog_callback);
> >
> > usb_set_intfdata(interface, hw);
> >
> > @@ -6226,6 +6262,8 @@ static void rtl8xxxu_disconnect(struct usb_interface *interface)
> > mutex_destroy(&priv->usb_buf_mutex);
> > mutex_destroy(&priv->h2c_mutex);
> >
> > + cancel_delayed_work_sync(&priv->watchdog.ra_wq);
> > +
> > if (priv->udev->state != USB_STATE_NOTATTACHED) {
> > dev_info(&priv->udev->dev,
> > "Device still attached, trying to reset\n");
> > --
> > 2.21.0
> >