Re: [PATCH 4.8 2/2] brcmfmac: support get_channel cfg80211 callback

On 20 May 2016 at 09:42, Arend Van Spriel [off-list ref] wrote:

On 19-5-2016 13:02, Rafał Miłecki wrote:

quoted

This is important for brcmfmac as the firmware may pick different
channel than requested. This has been tested with BCM4366B1 (in D-Link
DIR-885L).

Can you elaborate? Is this for AP or STA mode?

This happens when using 5 GHz PHY with one AP interface. It seems
firmware respects: band, channel width & control channel location.
However it picks center channel in a more or less random way.

E.g. I configured hostapd to setup AP using 36 control channel with
VHT80 (chanspec 0xe02a). Almost every time I was restarting AP I got
firmware picking different chanspecs, all cases listed below:
0xe03a BND_5G | BW_80 | SB_LL | 58
0xe06a BND_5G | BW_80 | SB_LL | 106
0xe07a BND_5G | BW_80 | SB_LL | 122
0xe09b BND_5G | BW_80 | SB_LL | 155

I'm a bit disappointed seeing this FullMAC firmware doing such tricks
on its own. I would prefer to simply relay on hostapd doing this kind
of channel switching. I saw many times hostapd e.g. respecting my
40/80 MHz channel but switching control one in order to avoid
collisions with another AP's control frames on the same frequency.

On the other hand I never got this problem with BCM43602 using
Broadcom's official firmware, so it's some new feature you enabled
when building brcmfmac4366b-pcie.bin.

quoted

Signed-off-by: Rafał Miłecki <redacted>
---
 .../broadcom/brcm80211/brcmfmac/cfg80211.c         | 59 ++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
index 597495d..4fb9e3a 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c

@@ -4892,6 +4892,64 @@ exit:
      return err;
 }

+static int brcmf_cfg80211_get_channel(struct wiphy *wiphy,
+                                   struct wireless_dev *wdev,
+                                   struct cfg80211_chan_def *chandef)
+{
+     struct brcmf_cfg80211_info *cfg = wiphy_to_cfg(wiphy);
+     struct net_device *ndev = wdev->netdev;
+     struct brcmf_if *ifp = netdev_priv(ndev);

Can this operation be done on a P2P_DEVICE interface, ie. wdev->netdev
== NULL?

I don't have any experience with P2P, thanks a lot for pointing this to me!

quoted

+     struct brcmu_chan ch;
+     enum nl80211_band band = 0;
+     enum nl80211_chan_width width = 0;
+     u32 chanspec;
+     int freq, err;
+
+     err = brcmf_fil_iovar_int_get(ifp, "chanspec", &chanspec);
+     if (err) {
+             brcmf_err("chanspec failed (%d)\n", err);
+             return err;
+     }
+
+     ch.chspec = chanspec;
+     cfg->d11inf.decchspec(&ch);
+
+     switch (ch.band) {
+     case BRCMU_CHAN_BAND_2G:
+             band = NL80211_BAND_2GHZ;
+             break;
+     case BRCMU_CHAN_BAND_5G:
+             band = NL80211_BAND_5GHZ;
+             break;
+     }
+
+     switch (ch.bw) {
+     case BRCMU_CHAN_BW_80:
+             width = NL80211_CHAN_WIDTH_80;
+             break;
+     case BRCMU_CHAN_BW_40:
+             width = NL80211_CHAN_WIDTH_40;
+             break;
+     case BRCMU_CHAN_BW_20:
+             width = NL80211_CHAN_WIDTH_20;
+             break;
+     case BRCMU_CHAN_BW_80P80:
+             width = NL80211_CHAN_WIDTH_80P80;
+             break;

Not much sense to support this given that center_freq2 is set to zero below.

OK.
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html