Re: [PATCH v2] rtl8xxxu: Fix wifi low signal strength issue of RTL8723BU

[Daniel Drake <drake@endlessm.com>]

On Fri, Jul 5, 2019 at 10:27 AM Chris Chiu <chiu@endlessm.com> wrote:
> Per the code before REG_S0S1_PATH_SWITCH setting, the driver has told
> the co-processor the antenna is inverse.
>         memset(&h2c, 0, sizeof(struct h2c_cmd));
>         h2c.ant_sel_rsv.cmd = H2C_8723B_ANT_SEL_RSV;
>         h2c.ant_sel_rsv.ant_inverse = 1;
>         h2c.ant_sel_rsv.int_switch_type = 0;
>         rtl8xxxu_gen2_h2c_cmd(priv, &h2c, sizeof(h2c.ant_sel_rsv));
>
> At least the current modification is consistent with the antenna
> inverse setting.
> I'll verify on vendor driver about when/how the inverse be determined.

I checked this out. The codepath hit hardcodes it to the AUX port,
i.e. "inverted" setup:

EXhalbtc8723b1ant_PowerOnSetting():
    if(pBtCoexist->chipInterface == BTC_INTF_USB)
    {
        // fixed at S0 for USB interface
        pBtCoexist->fBtcWrite4Byte(pBtCoexist, 0x948, 0x0);

        u1Tmp |= 0x1;    // antenna inverse
        pBtCoexist->fBtcWriteLocalReg1Byte(pBtCoexist, 0xfe08, u1Tmp);

        pBoardInfo->btdmAntPos = BTC_ANTENNA_AT_AUX_PORT;
  }

So I'm further convinced that these performance-enhancing changes are
increasing consistency with the vendor driver.

Daniel