linux-kernel - Re: [PATCH 05/13] staging:rtl8192u: Remove AdvCoding and GreenField

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Message-ID: <20180928223212.GA4984@xux707-tw>
Date:   Fri, 28 Sep 2018 23:32:14 +0100
From:   John Whitmore <arigead@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     John Whitmore <johnfwhitmore@...il.com>,
        linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
        gregkh@...uxfoundation.org
Subject: Re: [PATCH 05/13] staging:rtl8192u: Remove AdvCoding and GreenField
 - Style

On Fri, Sep 28, 2018 at 05:31:40PM +0300, Dan Carpenter wrote:
> On Wed, Sep 26, 2018 at 08:16:56PM +0100, John Whitmore wrote:
> > The member variables AdvCoding and GreenField are unused in code so
> > have been removed from the structure and associated initialisation
> > function.
> > 
> > This is a coding style change which should have no impact on runtime
> > code execution.
> > 
> > Signed-off-by: John Whitmore <johnfwhitmore@...il.com>
> > ---
> >  drivers/staging/rtl8192u/ieee80211/rtl819x_HT.h     | 2 --
> >  drivers/staging/rtl8192u/ieee80211/rtl819x_HTProc.c | 2 --
> >  2 files changed, 4 deletions(-)
> > 
> > diff --git a/drivers/staging/rtl8192u/ieee80211/rtl819x_HT.h b/drivers/staging/rtl8192u/ieee80211/rtl819x_HT.h
> > index 64d5359cf7e2..83fb8f34ccbd 100644
> > --- a/drivers/staging/rtl8192u/ieee80211/rtl819x_HT.h
> > +++ b/drivers/staging/rtl8192u/ieee80211/rtl819x_HT.h
> > @@ -39,10 +39,8 @@ enum ht_extension_chan_offset {
> >  
> >  struct ht_capability_ele {
> >  	//HT capability info
> > -	u8	AdvCoding:1;
> >  	u8	ChlWidth:1;
> >  	u8	MimoPwrSave:2;
> > -	u8	GreenField:1;
> >  	u8	ShortGI20Mhz:1;
> >  	u8	ShortGI40Mhz:1;
> >  	u8	TxSTBC:1;
> 
> I feel like we discussed this before.  I'm pretty sure this comes from
> the firmware and so the format can't be changed.  When I look at
> rtllib_parse_mife_generic() then I think that "info_element" probably
> comes from the firmware.
> 
> I wouldn't want to accept this with out someone testing it.
> 
> regards,
> dan carpenter
> 

Thank you and sorry about not helping the signal to noise ratio on here.

I agree that a bit field like that and it looks like it comes from
firmware, but my question or possibly obsession was where. There are
structures inside structures, but they are all allocated from RAM.
Because of that I expected to find a memcopy from the device, or given
that the bitfield is initialised with values that it might be memcopy'd
to the device. I just couldn't find that memcopy, but that's down to
my untrained eye. I'll stumble across it in some obscure corner of the
driver.