[PATCH] nl/cfg80211: advertise OBSS scan offload capability

[PATCH] nl/cfg80211: advertise OBSS scan offload capability

[Bing Zhao]

From: Amitkumar Karwar <akarwar@marvell.com>

New flag is added to inform userspace that this driver doesn't
internally perform OBSS scan. It can use this feature available
in userspace application.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
---
 include/uapi/linux/nl80211.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index cbd2d6b..97c096c 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -3057,6 +3057,8 @@ enum nl80211_ap_sme_features {
  * @NL80211_FEATURE_SCAN_FLUSH: Scan flush is supported
  * @NL80211_FEATURE_AP_SCAN: Support scanning using an AP vif
  * @NL80211_FEATURE_VIF_TXPOWER: The driver supports per-vif TX power setting
+ * @NL80211_FEATURE_OBSS_SCAN_OFFLOAD: This driver expects user space to perform
+ *	OBSS scan and generate 20/40 BSS coex reports.
  */
 enum nl80211_feature_flags {
 	NL80211_FEATURE_SK_TX_STATUS			= 1 << 0,
@@ -3069,6 +3071,7 @@ enum nl80211_feature_flags {
 	NL80211_FEATURE_SCAN_FLUSH			= 1 << 7,
 	NL80211_FEATURE_AP_SCAN				= 1 << 8,
 	NL80211_FEATURE_VIF_TXPOWER			= 1 << 9,
+	NL80211_FEATURE_OBSS_SCAN_OFFLOAD		= 1 << 10,
 };
 
 /**
-- 
1.8.0

Re: [PATCH] nl/cfg80211: advertise OBSS scan offload capability

[Johannes Berg]

On Thu, 2012-11-08 at 14:54 -0800, Bing Zhao wrote:
> From: Amitkumar Karwar <akarwar@marvell.com>
> 
> New flag is added to inform userspace that this driver doesn't
> internally perform OBSS scan. It can use this feature available
> in userspace application.

Shouldn't that be a little more precisely worded? Most drivers already
expect wpa_s to do this, but apparently the assumption was that without
the flag, full-MAC drivers, i.e. drivers implementing the nl80211
connect API (rather than auth/assoc) do it themselves?

Or maybe mac80211 should just set the flag?

johannes

RE: [PATCH] nl/cfg80211: advertise OBSS scan offload capability

[Bing Zhao]

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Re: [PATCH] nl/cfg80211: advertise OBSS scan offload capability

[Johannes Berg]

On Fri, 2012-11-09 at 12:18 -0800, Bing Zhao wrote:

> > > New flag is added to inform userspace that this driver doesn't
> > > internally perform OBSS scan. It can use this feature available
> > > in userspace application.
> > 
> > Shouldn't that be a little more precisely worded? Most drivers already
> > expect wpa_s to do this, but apparently the assumption was that without
> > the flag, full-MAC drivers, i.e. drivers implementing the nl80211
> > connect API (rather than auth/assoc) do it themselves?
> 
> That's right.
> 
> > 
> > Or maybe mac80211 should just set the flag?
> 
> Currently wpa_s checks WPA_DRIVER_FLAGS_SME flag for OBSS scan.
> Since WPA_DRIVER_FLAGS_SME bit is set for mac80211, it's unnecessary to set this new flag.
> 
> Or, are you suggesting that we should set the new flag in mac80211
> (and all drivers that need OBSS scan feature in wpa_s) and replace
> WPA_DRIVER_FLAGS_SME check with the new flag?

I don't think that can be done, for the simple reason that wpa_s should
continue to work on older kernels.

Thus, I guess that wpa_s is going to continue with the assumption that
auth/assoc API implies also doing OBSS in wpa_s (which is a fair
assumption), but then I think we should simply change the documentation
of this new feature flag to indicate that it's interesting only in the
case of a driver that has connect API.

johannes

RE: [PATCH] nl/cfg80211: advertise OBSS scan offload capability

[Bing Zhao]

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