[Click] [click] How to modify ath9k driver if click-1.8.0 want to support 802.11n mode

[欧阳鑫]

Hi, everyone.
        I am running roofnet experiments on 2 Ubuntu hosts with 2.6.32-26
kernel. Both are AR5416 cards with ath9k driver, and I have updated ath9k
driver to compat-wireless-2011-01-15, and also patched. All cards run in
Monitor mode. The roofnet can run on high rates, and also can run on mode b
and mode g. But now I want to run on mode n, I know the radiotap element
currently included in click do not support the MCS rate fields necessary to
send frames at 11n rates. I look up much information and then find there is
already a patch to solve this problem:
       http://permalink.gmane.org/gmane.network.wireless.radiotap/239 .
       I only patch the ath9k driver include
wireless-testing/net/mac80211/rx.c and
wireless-testing/include/net/ieee80211_radiotap.h. And also modify
wireless-testing/net/mac80211/tx.c:

       switch (iterator.this_arg_index) {
            ..................
              case IEEE80211_RADIOTAP_DATA_RETRIES:
             /*
              * Only allow setting the number of retries in
              * conjunction with the rates, when the rate control
              * is bypassed.
              */
             if (info->flags & IEEE80211_TX_CTL_RC_BYPASS)
                 info->control.rates[0].count =
                     *iterator.this_arg;
             break;

     +   case IEEE80211_RADIOTAP_MCS: {
     +           u8 known, flags;
     +           known = *(iterator.this_arg);
     +          flags = *(iterator.this_arg + 1);
     +         // set Band width
     +          if (known & IEEE80211_RADIOTAP_MCS_HAVE_BW) {
     +                     if (flags & IEEE80211_RADIOTAP_MCS_BW_40)
     +                    info->control.rates[0].flags |=
IEEE80211_TX_RC_40_MHZ_WIDTH;
     +       }

     +       // set Rate index
     +         info->control.rates[0].flags |= IEEE80211_TX_RC_MCS;

     +        if (known & IEEE80211_RADIOTAP_MCS_HAVE_MCS)
     +               info->control.rates[0].idx = *(iterator.this_arg + 2);

     +         // set Guard interval
     +        if (known & IEEE80211_RADIOTAP_MCS_HAVE_GI) {
     +                if (flags & IEEE80211_RADIOTAP_MCS_SGI)
     +                       info->control.rates[0].flags |=
IEEE80211_TX_RC_SHORT_GI;
     +       }
     +    // set FMT
     +       if (known & IEEE80211_RADIOTAP_MCS_HAVE_FMT) {
     +               if (flags & IEEE80211_RADIOTAP_MCS_FMT_GF)
     +                      info->control.rates[0].flags |=
 IEEE80211_TX_RC_GREEN_FIELD;
     +       }

     +   // set FEC
     +      if (known & IEEE80211_RADIOTAP_MCS_HAVE_FEC) {
     +              if (flags & IEEE80211_RADIOTAP_MCS_FEC_LDPC)
     +                       info->flags |= IEEE80211_TX_CTL_LDPC;
     +        }
    break;
   }


     I do some experiments, but I find that the argument
iterator.this_arg_index   in  wireless-testing/net/mac80211/tx.c     switch
(iterator.this_arg_index)   is not equal IEEE80211_RADIOTAP_MCS, so the
ath9k driver can not support 80211n mode.
     I do not know why the argument iterator.this_arg_index is not equal
IEEE80211_RADIOTAP_MCS. Should I modify some other  *.c or  *.h files?
Could someone tell me how to do if you know something about it?  Thank you
very much!



Yours,

ouyang