linux-kernel - Re: staging: rtl8723bs: removal of 5G code

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Date:   Tue, 25 May 2021 15:40:13 +0200
From:   Fabio Aiuto <fabioaiuto83@...il.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Larry.Finger@...inger.net, gregkh@...uxfoundation.org,
        johannes@...solutions.net, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org
Subject: Re: staging: rtl8723bs: removal of 5G code

Hi Hans and everyone,

On Tue, May 25, 2021 at 12:07:55PM +0200, Hans de Goede wrote:
> Hi,
> 
> On 5/20/21 11:29 AM, Fabio Aiuto wrote:
> > Hi all,
> > 
> > I'm stick with removal of 5Ghz code from rtl8723bs wireless card driver
> > (in staging subsystem).
> > 
> > I think that this task comprehend deletion of all code managing
> > 80Mhz bandwidth and upper bandwidth (160 and 80+80). For the latter
> > it's simple, there's quite no code (unused enums and obsolete comments).
> > 
> > The former seems to be trickier, there are handlers like this:
> > 
> >         /* 3 Set Reg483 */
> >         SubChnlNum = phy_GetSecondaryChnl_8723B(Adapter);
> >         rtw_write8(Adapter, REG_DATA_SC_8723B, SubChnlNum);
> > 
> > phy_GetSecondaryChnl_8723B() contains code like:
> > 
> >         } else if (pHalData->CurrentChannelBW == CHANNEL_WIDTH_40) {
> >                 if (pHalData->nCur40MhzPrimeSC == HAL_PRIME_CHNL_OFFSET_UPPER)
> >                         SCSettingOf20 = VHT_DATA_SC_20_UPPER_OF_80MHZ;
> >                 else if (pHalData->nCur40MhzPrimeSC == HAL_PRIME_CHNL_OFFSET_LOWER)
> >                         SCSettingOf20 = VHT_DATA_SC_20_LOWER_OF_80MHZ;
> >         }
> > 
> > so if we are on a 40M channel some settings involving 80M are made and
> > the whole is then written on card registers.
> 
> I'm no wifi expert, so I was hoping someone else would respond...
> 
> With that said I believe you should keep this else block, this part of the
> function seems to select the order of the bonded channels when bonding
> multiple 20MHz channels together.
> 
> The "if (pHalData->CurrentChannelBW == CHANNEL_WIDTH_80) {}" part can be
> removed because on 2.4G only devices 80 MHz width is not supported, but
> the 40MHz bit should stay, the constants for the register bits may be named
> after the 80MHz option, but I believe these same register bits will impact
> the 40Mhz case too.

agreed, just remove the CHANNEL_WIDTH_80 branch is good

> 
> It might be a good idea to rename the constants to VHT_DATA_SC_20_*_OF_40MHZ
> in a separate patch.

good idea, I was misguided by the trailing *_80MHZ in constant name

> 
> Regards,
> 
> Hans
> 

thank you Hans,

fabio