RE: Question about IEEE80211_TX_CTL_NO_ACK in ath_9k

[李刚 <gang.li@watchdata.com>]

> 
> Hi!
> 
> On 12/19/2011 6:38 AM, 李刚 wrote:
> > Hi everybody!
> >
> > My wireless card is AR9280. I set the IEEE80211_TX_CTL_NO_ACK flag
before
> > send a packet, but found it no use. It still wait for an ACK. Then I
read
> > the code,
> > in ath9k_htc_tx_data(htc_drv_txrx.c) , it seems there is only two flags:
> >
> > #define ATH9K_HTC_TX_CTSONLY      0x1
> > #define ATH9K_HTC_TX_RTSCTS       0x2
> >
> > None is about ack.
> >
> > Does anyone know how to make this flag work properly?
> >
> 
> As an FYI if your card is a AR9280, then you should be looking in xmit.c
> and not at the HTC related code.

Hi, Daniel, Thanks you !

Sorry,  I didn't make it clear!  My 9280 is an USB card, so the related code
is htc_drv_*.c.



> 
> I am also working on this issue to enable per-frame no-ack and have
> already tracked it down to the following snippet in the function
> ieee80211_tx_prepare (mac80211/tx.c).
> 
> if (is_multicast_ether_addr(hdr->addr1)) {
> tx->flags &= ~IEEE80211_TX_UNICAST;
> info->flags |= IEEE80211_TX_CTL_NO_ACK;
> } else {
> tx->flags |= IEEE80211_TX_UNICAST;
> if (unlikely(local->wifi_wme_noack_test))
> info->flags |= IEEE80211_TX_CTL_NO_ACK;
> else
> info->flags &= ~IEEE80211_TX_CTL_NO_ACK;
> }

I have seen these codes in tx.c,  and at first I thought it should work, but
does not.


> 
> So if you send a unicast frame without this wifi_wme_noack_test flag set
> then mac80211 will force the frame to require an ACK. To set the flag,
> 
> # sudo -s "echo 1> /sys/kernel/debug/ieee80211/phy0/noack"
> 
> Assuming phy0 is the wireless card with which you are wanting to do the
> frame injection. The downside to this is that now every frame is passed
> to ath9k with the no ack flag set.
> 
> Daniel
> 
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