[PATCH] mac80211: Enable sw scan with chan context

[PATCH] mac80211: Enable sw scan with chan context

[Mahesh Palivela]

From: Mahesh Palivela <maheshp@posedge.com>

Enable software scan with channel context in use.

Signed-off-by: Mahesh Palivela <maheshp@posedge.com>
---

  net/mac80211/scan.c |   17 +++++++++++------
  1 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 43a45cf..58076ec 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -309,10 +309,6 @@ EXPORT_SYMBOL(ieee80211_scan_completed);

  static int ieee80211_start_sw_scan(struct ieee80211_local *local)
  {
-	/* Software scan is not supported in multi-channel cases */
-	if (local->use_chanctx)
-		return -EOPNOTSUPP;
-
  	/*
  	 * Hardware/driver doesn't support hw_scan, so use software
  	 * scanning instead. First send a nullfunc frame with power save
@@ -387,9 +383,18 @@ static void ieee80211_scan_state_send_probe(struct 
ieee80211_local *local,
  {
  	int i;
  	struct ieee80211_sub_if_data *sdata;
-	enum ieee80211_band band = local->hw.conf.channel->band;
+	enum ieee80211_band band;
+	struct ieee80211_channel *scan_chan;
  	u32 tx_flags;

+	if (!local->use_chanctx) {
+		band = local->hw.conf.channel->band;
+		scan_chan = local->hw.conf.channel;
+	} else {
+		band = local->scan_channel->band;
+		scan_chan = local->scan_channel;
+	}
+
  	tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
  	if (local->scan_req->no_cck)
  		tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
@@ -404,7 +409,7 @@ static void ieee80211_scan_state_send_probe(struct 
ieee80211_local *local,
  			local->scan_req->ssids[i].ssid_len,
  			local->scan_req->ie, local->scan_req->ie_len,
  			local->scan_req->rates[band], false,
-			tx_flags, local->hw.conf.channel, true);
+			tx_flags, scan_chan, true);

  	/*
  	 * After sending probe requests, wait for probe responses

Re: [PATCH] mac80211: Enable sw scan with chan context

[Johannes Berg]

On Mon, 2013-03-11 at 19:35 +0530, Mahesh Palivela wrote:
> From: Mahesh Palivela <maheshp@posedge.com>
> 
> Enable software scan with channel context in use.

I don't think this will even work, but even if it did I think it's too
painful with off-channel etc.

johannes

Re: [PATCH] mac80211: Enable sw scan with chan context

[Mahesh Palivela]

On 3/11/2013 8:09 PM, Johannes Berg wrote:
> On Mon, 2013-03-11 at 19:35 +0530, Mahesh Palivela wrote:
>> From: Mahesh Palivela <maheshp@posedge.com>
>>
>> Enable software scan with channel context in use.
>
> I don't think this will even work, but even if it did I think it's too
> painful with off-channel etc.
>

I tested this patch. scan works. Anyways chan context is a WIP.
There is no driver which is using the chan ctx work yet.
I will continue adding code for chan ctx.

> johannes
>

-- 
Thanks,
Mahesh

Re: [PATCH] mac80211: Enable sw scan with chan context

[Johannes Berg]

On Mon, 2013-03-11 at 20:51 +0530, Mahesh Palivela wrote:

> I tested this patch. scan works. 

Works how? It never tells the driver to go to a different channel ...

Besides, telling the driver to go to one channel via the hw_config call,
and using chanctx for vif configuration seems like a really bad idea.

> Anyways chan context is a WIP.

It pretty much works.

> There is no driver which is using the chan ctx work yet.

There is, our mvm driver uses it.

> I will continue adding code for chan ctx.

What are you trying to achieve anyway?

johannes

Re: [PATCH] mac80211: Enable sw scan with chan context

[Mahesh Palivela]

On Mon, 2013-03-11 at 17:25 +0200, Johannes Berg wrote:
> On Mon, 2013-03-11 at 20:51 +0530, Mahesh Palivela wrote:
> 
> > I tested this patch. scan works. 
> 
> Works how? It never tells the driver to go to a different channel ...

sorry. I missed this. But my patch takes care of crash in mac80211 once
we remove 'use_chanctx' check in sw_scan function.

> 
> Besides, telling the driver to go to one channel via the hw_config call,
> and using chanctx for vif configuration seems like a really bad idea.
> 

Agree.

> > Anyways chan context is a WIP.
> 
> It pretty much works.

For AP mode yes it works. But for STA mode, we have work I guess.

> 
> > There is no driver which is using the chan ctx work yet.
> 
> There is, our mvm driver uses it.
> 

Thanks for the info. I will take a look.

> > I will continue adding code for chan ctx.
> 
> What are you trying to achieve anyway?
> 

VHT assoc. To enable VHT on both AP and STA. For VHT to work we need
chan_ctx. Isn't it?


> johannes
> 

Re: [PATCH] mac80211: Enable sw scan with chan context

[Karl Beldan]

On Tue, Mar 12, 2013 at 08:39:26AM +0530, Mahesh Palivela wrote:
> On Mon, 2013-03-11 at 17:25 +0200, Johannes Berg wrote:
> > On Mon, 2013-03-11 at 20:51 +0530, Mahesh Palivela wrote:
> > 
> > > I tested this patch. scan works. 
> > 
> > Works how? It never tells the driver to go to a different channel ...
> 
> sorry. I missed this. But my patch takes care of crash in mac80211 once
> we remove 'use_chanctx' check in sw_scan function.
> 
> > 
> > Besides, telling the driver to go to one channel via the hw_config call,
> > and using chanctx for vif configuration seems like a really bad idea.
> > 
> 
> Agree.
> 
> > > Anyways chan context is a WIP.
> > 
> > It pretty much works.
> 
> For AP mode yes it works. But for STA mode, we have work I guess.
> 
> > 
> > > There is no driver which is using the chan ctx work yet.
> > 
> > There is, our mvm driver uses it.
> > 
> 
It uses hw scan and roc, and thus can use the chanctxes as is.
 
Karl

Re: [PATCH] mac80211: Enable sw scan with chan context

[Johannes Berg]

On Tue, 2013-03-12 at 08:39 +0530, Mahesh Palivela wrote:
> On Mon, 2013-03-11 at 17:25 +0200, Johannes Berg wrote:
> > On Mon, 2013-03-11 at 20:51 +0530, Mahesh Palivela wrote:
> > 
> > > I tested this patch. scan works. 
> > 
> > Works how? It never tells the driver to go to a different channel ...
> 
> sorry. I missed this. But my patch takes care of crash in mac80211 once
> we remove 'use_chanctx' check in sw_scan function.

Yes, but it doesn't make it *do* anything, so the patch is completely
pointless. I don't see how chanctx and SW scan/roc can ever possibly
work together.

> > > Anyways chan context is a WIP.
> > 
> > It pretty much works.
> 
> For AP mode yes it works. But for STA mode, we have work I guess.

You may have, but in mac80211 it should work just as designed.

> VHT assoc. To enable VHT on both AP and STA. For VHT to work we need
> chan_ctx. Isn't it?

Right now, yes, you do.

However, I would argue that if you really want only VHT support, you
should remove the channel/channel_type fields from struct ieee80211_conf
and instead add a cfg80211_chan_def. This means a lot of changes in all
the drivers, but I'd hate to see the data all duplicated, and the
changes are trivial anyway.

johannes

Re: [PATCH] mac80211: Enable sw scan with chan context

[Mahesh Palivela]

On 03/11/2013 08:55 PM, Johannes Berg wrote:
> On Mon, 2013-03-11 at 20:51 +0530, Mahesh Palivela wrote:
>
>> I tested this patch. scan works.
> Works how? It never tells the driver to go to a different channel ...
>
> Besides, telling the driver to go to one channel via the hw_config call,
> and using chanctx for vif configuration seems like a really bad idea.
I think hw_config() should be modified to add vif param and call drivers?
can we proceed with that approach?

Thanks,
Mahesh