[rt2x00-users] [PATCH] rt2x00: rt2800lib: disable HT40 for now as it causes reception problems

[Ivo van Doorn]

On Friday 23 April 2010, Gertjan van Wingerde wrote:
> On 04/23/10 15:05, Helmut Schaa wrote:
> > Disable HT40 support for now as it causes rx problems with HT40 capable
> > 11n APs (when mac80211 enables HT40, rx is completely disfunctional).
> > 
> > Once the rt2800 HT code is capable of using HT40 we should enable the
> > flag again.
> > 
> > I only tested this patch with a rt305x SoC device, nevertheless the
> > patch disables HT40 also on PCI and USB rt2800 devices.
> > 
> > Signed-off-by: Helmut Schaa <helmut.schaa at googlemail.com>
> 
> I can confirm that this also helps for PCI and USB devices.
> With this patch applied all my rt28xx and rt30xx based devices starting working correctly.
> 
> So, definately,
> 
> Acked-by: Gertjan van Wingerde <gwingerde at gmail.com>

And also thanks for figuring this out, this at least gives a good starting
point for investigation for resolving the last issues. :)

Acked-by: Ivo van Doorn <IvDoorn at gmail.com>

> > ---
> > 
> > Using this patch I was able to associate a rt305x SoC device with my 11n
> > capable AP using WPA and the connection basically works although I see lots
> > of retried frames when sniffing the wireless traffic.
> > 
> > If someone already had success with rt2800 and HT40 capable APs we should
> > consider to only conditionally unset the HT40 flag for 305x SoC devices.
> > 
> >  drivers/net/wireless/rt2x00/rt2800lib.c |    5 ++++-
> >  1 files changed, 4 insertions(+), 1 deletions(-)
> > 
> > diff --git a/drivers/net/wireless/rt2x00/rt2800lib.c b/drivers/net/wireless/rt2x00/rt2800lib.c
> > index 2648f31..aa02ff6 100644
> > --- a/drivers/net/wireless/rt2x00/rt2800lib.c
> > +++ b/drivers/net/wireless/rt2x00/rt2800lib.c
> > @@ -2318,8 +2318,11 @@ int rt2800_probe_hw_mode(struct rt2x00_dev *rt2x00dev)
> >  	else
> >  		spec->ht.ht_supported = false;
> >  
> > +	/*
> > +	 * Don't set IEEE80211_HT_CAP_SUP_WIDTH_20_40 for now as it causes
> > +	 * reception problems with HT40 capable 11n APs
> > +	 */
> >  	spec->ht.cap =
> > -	    IEEE80211_HT_CAP_SUP_WIDTH_20_40 |
> >  	    IEEE80211_HT_CAP_GRN_FLD |
> >  	    IEEE80211_HT_CAP_SGI_20 |
> >  	    IEEE80211_HT_CAP_SGI_40 |
> 
>