linux-kernel - Re: [PATCH] rtl8xxxu: Fix wifi low signal strength issue of RTL8723BU

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Date:   Mon, 1 Jul 2019 13:09:09 +0800
From:   Chris Chiu <chiu@...lessm.com>
To:     Jes Sorensen <jes.sorensen@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        David Miller <davem@...emloft.net>
Cc:     linux-wireless <linux-wireless@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Linux Upstreaming Team <linux@...lessm.com>
Subject: Re: [PATCH] rtl8xxxu: Fix wifi low signal strength issue of RTL8723BU

On Thu, Jun 27, 2019 at 5:52 PM Chris Chiu <chiu@...lessm.com> wrote:
>
> The WiFi tx power of RTL8723BU is extremely low after booting. So
> the WiFi scan gives very limited AP list and it always fails to
> connect to the selected AP. This module only supports 1x1 antenna
> and the antenna is switched to bluetooth due to some incorrect
> register settings.
>
> This commit hand over the antenna control to PTA, the wifi signal
> will be back to normal and the bluetooth scan can also work at the
> same time. However, the btcoexist still needs to be handled under
> different circumstances. If there's a BT connection established,
> the wifi still fails to connect until disconneting the BT.
>
> Signed-off-by: Chris Chiu <chiu@...lessm.com>
> ---
>  drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c | 9 ++++++---
>  drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c  | 3 ++-
>  2 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> index 3adb1d3d47ac..6c3c70d93ac1 100644
> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_8723b.c
> @@ -1525,7 +1525,7 @@ static void rtl8723b_enable_rf(struct rtl8xxxu_priv *priv)
>         /*
>          * WLAN action by PTA
>          */
> -       rtl8xxxu_write8(priv, REG_WLAN_ACT_CONTROL_8723B, 0x04);
> +       rtl8xxxu_write8(priv, REG_WLAN_ACT_CONTROL_8723B, 0x0c);
>
>         /*
>          * BT select S0/S1 controlled by WiFi
> @@ -1568,9 +1568,12 @@ static void rtl8723b_enable_rf(struct rtl8xxxu_priv *priv)
>         rtl8xxxu_gen2_h2c_cmd(priv, &h2c, sizeof(h2c.ant_sel_rsv));
>
>         /*
> -        * 0x280, 0x00, 0x200, 0x80 - not clear
> +        * Different settings per different antenna position.
> +        * Antenna switch to BT: 0x280, 0x00 (inverse)
> +        * Antenna switch to WiFi: 0x0, 0x280 (inverse)
> +        * Antenna controlled by PTA: 0x200, 0x80 (inverse)
>          */
> -       rtl8xxxu_write32(priv, REG_S0S1_PATH_SWITCH, 0x00);
> +       rtl8xxxu_write32(priv, REG_S0S1_PATH_SWITCH, 0x80);
>
>         /*
>          * Software control, antenna at WiFi side
> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> index 8136e268b4e6..87b2179a769e 100644
> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> @@ -3891,12 +3891,13 @@ static int rtl8xxxu_init_device(struct ieee80211_hw *hw)
>
>         /* Check if MAC is already powered on */
>         val8 = rtl8xxxu_read8(priv, REG_CR);
> +       val16 = rtl8xxxu_read16(priv, REG_SYS_CLKR);
>
>         /*
>          * Fix 92DU-VC S3 hang with the reason is that secondary mac is not
>          * initialized. First MAC returns 0xea, second MAC returns 0x00
>          */
> -       if (val8 == 0xea)
> +       if (val8 == 0xea || !(val16 & BIT(11)))
>                 macpower = false;
>         else
>                 macpower = true;
> --
> 2.11.0
>

Gentle ping. Cheers.

Chris