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

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

[Jon Hunter]

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,
-- 
1.9.1

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

[Larry Finger]

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().

Larry


Larry

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

[Jon Hunter]

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