On Friday 21 January 2011 03:55:51 Sujith wrote:
> This series is the preliminary work for enabling AP mode for ath9k_htc.
>
> A firmware update is needed, place look at:
> http://wireless.kernel.org/en/users/Drivers/ath9k_htc#AP_Mode
>
> Known issues:
>
> * Beacon misses under heavy TX load
> ( hopefully, a fix would be sent out soon).
>
> This has not been tested rigorously, so consider this series as
> experimental code.
>
Hey that's great! I gave this series a quick whirl and it worked on the first
try!
I had no probles getting ath9k to connect, well apart form a WARN_ON_ONCE
WARNING: at net/mac80211/tx.c:57 ieee80211_duration+0x50/0x1b3 [mac80211]()
Call Trace:
[ 322.971940] [<ffffffffa01d1cb0>] ? ieee80211_duration+0x50/0x1b3 [mac80211]
[ 322.979297] [<ffffffffa01d33d5>] ? invoke_tx_handlers+0xf65/0x1001
[mac80211]
[ 322.987053] [<ffffffffa01d0f2d>] ?
ieee80211_prepare_and_rx_handle+0x7ff/0x845 [mac80211]
[ 322.995865] [<ffffffffa0004f5d>] ? usb_hcd_giveback_urb+0x76/0xa5 [usbcore]
but that's ok, ieee80211_duration does not make sense when
the rate control is done by the firmware.
--------
But what seems to be strange is the tx feedback...
Because it looks like ath9k_htc just sets IEEE80211_TX_STAT_ACK
for every frame, which obviously can't be "true", right? ;)
This might also break mac80211's *unicast buffering*.
Because the code in ieee80211_tx_status - net/mac80211/status.c
works like this:
211 acked = !!(info->flags & IEEE80211_TX_STAT_ACK);
212 if (!acked && test_sta_flags(sta, WLAN_STA_PS_STA)) {
213 /*
214 * The STA is in power save mode, so assume
215 * that this TX packet failed because of that.
216 */
217 ieee80211_handle_filtered_frame(local, sta, skb);
218 rcu_read_unlock();
219 return;
220 }
...
239 if (info->flags & IEEE80211_TX_STAT_TX_FILTERED) {
240 ieee80211_handle_filtered_frame(local, sta, skb);
241 rcu_read_unlock();
242 return;
243 } else {
244 if (!acked)
245 sta->tx_retry_failed++;
246 sta->tx_retry_count += retry_count;
247 }
so, mac80211 will never know when it needs to resend certain
frame which could be affected by the race between the "sleepy"
station sending a frame with a PSM-bit set and mac80211 finally
updating the WLAN_STA_PS_STA flag.
[see long comment in mac80211/status.c @ line 73]
unless of course, you don't need it and the firmware can
buffer those frames until the STA comes back?!
Best regards,
Christian
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