Re: [RFC PATCH] rtl8192cu: Fix beacon support in AP mode

[Jon Hunter <jgchunter@gmail.com>]

Hi Larry,

On 02/18/2015 09:24 PM, Larry Finger wrote:
> On 02/18/2015 01:51 PM, Jon Hunter wrote:
>> When using the rtl8192cu in AP mode a few devices (an android phone,
>> iphone and ipad) were unable to associate, where as the laptops I tried
>> could. Using wireshark to sniff the wlan traffic, it appears that the
>> rtl8192cu is not beaconing, however, it is responding to broadcast
>> probe requests and so devices are able to detect the AP.
>>
>> Searching the archives the same issue was reported for this WLAN device
>> and a fix to send an initial beacon frame was proposed [1]. This was
>> rejected as it was modifying the rtlwifi core. This change does the
>> same but from within the rtl8192cu driver and appears to fix the problem.
>>
>> Please note that although this does fix the problem, I don't know if this
>> is the best way or correct way to fix the problem, hence the request for
>> comment.
>>
>> [1] http://permalink.gmane.org/gmane.linux.kernel.wireless.general/96770
>>
>> Signed-off-by: Jon Hunter <jgchunter@gmail.com>
>>
>> Cc: Larry Finger <Larry.Finger@lwfinger.net>
>> Cc: Chaoming Li <chaoming_li@realsil.com.cn>
>> Cc: coekbe@gmail.com
>> ---
>>   drivers/net/wireless/rtlwifi/rtl8192cu/hw.c | 19 +++++++++++++++++++
>>   1 file changed, 19 insertions(+)
>>
>> diff --git a/drivers/net/wireless/rtlwifi/rtl8192cu/hw.c
>> b/drivers/net/wireless/rtlwifi/rtl8192cu/hw.c
>> index fe4b699..4fbca80 100644
>> --- a/drivers/net/wireless/rtlwifi/rtl8192cu/hw.c
>> +++ b/drivers/net/wireless/rtlwifi/rtl8192cu/hw.c
>> @@ -1520,6 +1520,22 @@ void
>> rtl92cu_set_beacon_related_registers(struct ieee80211_hw *hw)
>>       _beacon_function_enable(hw, true, true);
>>   }
>>
>> +static void _beacon_send_frame(struct ieee80211_hw *hw)
>> +{
>> +    struct rtl_priv *rtlpriv = rtl_priv(hw);
>> +    struct rtl_mac *mac = rtl_mac(rtl_priv(hw));
>> +    struct ieee80211_sta *sta;
>> +    struct rtl_tcb_desc tcb_desc;
>> +    struct sk_buff *skb;
>> +    memset(&tcb_desc, 0, sizeof(struct rtl_tcb_desc));
>> +
>> +    skb = ieee80211_beacon_get(hw, mac->vif);
>> +    sta = rtl_find_sta(hw, mac->bssid);
>> +
>> +    if (!rtlpriv->intf_ops->waitq_insert(hw, sta, skb))
>> +        rtlpriv->intf_ops->adapter_tx(hw, sta, skb, &tcb_desc);
>> +}
>> +
>>   void rtl92cu_set_beacon_interval(struct ieee80211_hw *hw)
>>   {
>>       struct rtl_priv *rtlpriv = rtl_priv(hw);
>> @@ -1529,6 +1545,9 @@ void rtl92cu_set_beacon_interval(struct
>> ieee80211_hw *hw)
>>       RT_TRACE(rtlpriv, COMP_BEACON, DBG_DMESG, "beacon_interval:%d\n",
>>            bcn_interval);
>>       rtl_write_word(rtlpriv, REG_BCN_INTERVAL, bcn_interval);
>> +
>> +        /* Send initial beacon frame to start beaconing */
>> +    _beacon_send_frame(hw);
>>   }
>>
>>   void rtl92cu_update_interrupt_mask(struct ieee80211_hw *hw,
>>
> 
> In the current mainline merge between 3.19 and 3.20-rc1, there is code
> that implements the initial beacon start in the core. The main commit is
> 33511b157bbc. A second commit, which fixes a problem in mesh beacons, is
> found in 0b70dc273c13. These were much less intrusive than the one that
> was rejected, thus they were accepted into the core. I just tested
> creating an AP using NetworkManager and I was able to connect to a
> Kindle Fire HD, which is an Android device.
> 
> Do these patches not fix the problem for you? There is a report that the
> beacon startup is unreliable. Perhaps it may be necessary to change the
> static send_beacon_frame() in the core into rtl_send_beacon_frame(),
> make it be exported, and call it from rtl92cu_set_beacon_interval().

Thanks. I had not tried the very latest main for a couple weeks. Yes I
can confirm that these do resolve the problem for me and I can see it
sending beacon frames now. Brilliant!

Cheers Jon