[PATCH] iwlwifi: add option to disable 5GHz band

[PATCH] iwlwifi: add option to disable 5GHz band

[Stanislaw Gruszka]

There are various problems happened on 5GHz band not observed on
2.4 GHz (microcode errors, queue stuck, etc... ) . Also roaming
between 5GHz AP and 2GHz does not work very well. To workaround
the problems add option to disable 5GHz support. This will help
on environments where APs are dual-band, and devices will not try
to associate on band where issues happen.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
 drivers/net/wireless/iwlwifi/iwl-agn.c    |    6 ++++++
 drivers/net/wireless/iwlwifi/iwl-shared.h |    2 ++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c
index 7db3986..d254640 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.c
@@ -1329,6 +1329,9 @@ static int iwl_init_geos(struct iwl_priv *priv)
 		priv->hw_params.sku &= ~EEPROM_SKU_CAP_BAND_52GHZ;
 	}
 
+	if (iwlagn_mod_params.disable_5ghz)
+		priv->bands[IEEE80211_BAND_5GHZ].n_channels = 0;
+
 	IWL_INFO(priv, "Tunable channels: %d 802.11bg, %d 802.11a channels\n",
 		   priv->bands[IEEE80211_BAND_2GHZ].n_channels,
 		   priv->bands[IEEE80211_BAND_5GHZ].n_channels);
@@ -2472,3 +2475,6 @@ module_param_named(auto_agg, iwlagn_mod_params.auto_agg,
 		bool, S_IRUGO);
 MODULE_PARM_DESC(auto_agg,
 		 "enable agg w/o check traffic load (default: enable)");
+
+module_param_named(5ghz_disable, iwlagn_mod_params.disable_5ghz, bool, S_IRUGO);
+MODULE_PARM_DESC(5ghz_disable, "disable 5GHz band (default: 0 [enabled])");
diff --git a/drivers/net/wireless/iwlwifi/iwl-shared.h b/drivers/net/wireless/iwlwifi/iwl-shared.h
index 35bd83c..53cbbd5 100644
--- a/drivers/net/wireless/iwlwifi/iwl-shared.h
+++ b/drivers/net/wireless/iwlwifi/iwl-shared.h
@@ -129,6 +129,7 @@ extern struct iwl_mod_params iwlagn_mod_params;
  * @ant_coupling: antenna coupling in dB, default = 0
  * @bt_ch_announce: BT channel inhibition, default = enable
  * @auto_agg: enable agg. without check, default = true
+ * @disable_5ghz: disable 5GHz capability, default = false
  */
 struct iwl_mod_params {
 	int sw_crypto;
@@ -145,6 +146,7 @@ struct iwl_mod_params {
 	int ant_coupling;
 	bool bt_ch_announce;
 	bool auto_agg;
+	bool disable_5ghz;
 };
 
 /**
-- 
1.7.1

Re: [PATCH] iwlwifi: add option to disable 5GHz band

[Guy, Wey-Yi]

Hi Stanislaw,

On Thu, 2012-04-19 at 12:11 +0200, Stanislaw Gruszka wrote:
> There are various problems happened on 5GHz band not observed on
> 2.4 GHz (microcode errors, queue stuck, etc... ) . Also roaming
> between 5GHz AP and 2GHz does not work very well. To workaround
> the problems add option to disable 5GHz support. This will help
> on environments where APs are dual-band, and devices will not try
> to associate on band where issues happen.
> 
> Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
> ---
I will push into iwlwifi tree, run regression test, then push together
with our internal patches if it is ok for you

Thanks
Wey 

Re: [PATCH] iwlwifi: add option to disable 5GHz band

[Stanislaw Gruszka]

On Thu, Apr 19, 2012 at 06:50:22AM -0700, Guy, Wey-Yi wrote:
> I will push into iwlwifi tree, run regression test, then push together
> with our internal patches if it is ok for you

Yes, that's fine.

Stanislaw

Re: [PATCH] iwlwifi: add option to disable 5GHz band

[Johannes Berg]

On 4/19/2012 3:11 AM, Stanislaw Gruszka wrote:
> There are various problems happened on 5GHz band not observed on
> 2.4 GHz (microcode errors, queue stuck, etc... ) . Also roaming
> between 5GHz AP and 2GHz does not work very well. To workaround
> the problems add option to disable 5GHz support. This will help
> on environments where APs are dual-band, and devices will not try
> to associate on band where issues happen.

Would it make sense to somehow do this in cfg80211? Today, our driver 
may be the only one having this problem (which I've never really heard 
about?), but is it always going to be?

johannes

Re: [PATCH] iwlwifi: add option to disable 5GHz band

[Marcel Holtmann]

Hi Johannes,

> > There are various problems happened on 5GHz band not observed on
> > 2.4 GHz (microcode errors, queue stuck, etc... ) . Also roaming
> > between 5GHz AP and 2GHz does not work very well. To workaround
> > the problems add option to disable 5GHz support. This will help
> > on environments where APs are dual-band, and devices will not try
> > to associate on band where issues happen.
> 
> Would it make sense to somehow do this in cfg80211? Today, our driver 
> may be the only one having this problem (which I've never really heard 
> about?), but is it always going to be?

honestly I have seen 5GHz problems with our driver multiple times. I
always ended up disabling 5GHz support in the AP since I rarely have
time to debug this. It only happens after long time of operation for me,
but was like super annoying all the time.

And I had similar issues with N support.

I would personally be fine with a global debugfs option within cfg80211
to disable it.

Regards

Marcel

Re: [PATCH] iwlwifi: add option to disable 5GHz band

[Guy, Wey-Yi]

On Thu, 2012-04-19 at 17:56 +0200, Marcel Holtmann wrote:
> Hi Johannes,
> 
> > > There are various problems happened on 5GHz band not observed on
> > > 2.4 GHz (microcode errors, queue stuck, etc... ) . Also roaming
> > > between 5GHz AP and 2GHz does not work very well. To workaround
> > > the problems add option to disable 5GHz support. This will help
> > > on environments where APs are dual-band, and devices will not try
> > > to associate on band where issues happen.
> > 
> > Would it make sense to somehow do this in cfg80211? Today, our driver 
> > may be the only one having this problem (which I've never really heard 
> > about?), but is it always going to be?
> 
> honestly I have seen 5GHz problems with our driver multiple times. I
> always ended up disabling 5GHz support in the AP since I rarely have
> time to debug this. It only happens after long time of operation for me,
> but was like super annoying all the time.
> 
> And I had similar issues with N support.
> 
> I would personally be fine with a global debugfs option within cfg80211
> to disable it.
> 
> Regards
> 
I don't see it hurt we have the option to disable the %GHz support in
iwlwifi. We could always change it later.

Thanks
Wey

Re: [PATCH] iwlwifi: add option to disable 5GHz band

[Stanislaw Gruszka]

On Thu, Apr 19, 2012 at 07:21:05AM -0700, Johannes Berg wrote:
> On 4/19/2012 3:11 AM, Stanislaw Gruszka wrote:
> >There are various problems happened on 5GHz band not observed on
> >2.4 GHz (microcode errors, queue stuck, etc... ) . Also roaming
> >between 5GHz AP and 2GHz does not work very well. To workaround
> >the problems add option to disable 5GHz support. This will help
> >on environments where APs are dual-band, and devices will not try
> >to associate on band where issues happen.
> 
> Would it make sense to somehow do this in cfg80211?
It has more sense, but doing this in cfg80211 is a bit more complicated,
at least I do not see an easy way. 

> Today, our
> driver may be the only one having this problem (which I've never
> really heard about?)
I filed bug 2351 on your bugzilla, which explicitly state issue it's
a 5GHz problem.

There are various other bug reports about iwlwifi random malfunction
(with no message in dmesg or queue stuck or microcode error). Some of
them are probably 5GHz problem too, but since nobody work on that
bugzillas nobody figure this out.

Regarding 2GHz <-> 5GHz roaming, I'm seeing lot's of problems with that
on older kernels. Did not test on new kernel though. Perhaps issues are
now mitigated or fixed by your assoc/auth redesign, but I did not check
yet.

Stanislaw