On Wed, Jan 11, 2012 at 5:41 PM, Christian Lamparter <chunkeey@xxxxxxxxxxxxxx> wrote: > On Thursday, January 12, 2012 12:07:54 AM Harshal Chhaya wrote: >> Does the carl9170 driver/firmware allow real-time updates to the tx >> power parameter? > > No. not yet. > >> On my AR9170-based AP, I can't set the tx power using either 'iw' or 'iwconfig'. >> >> 'iw' fails with an error message: >> >> root@OpenWrt:/etc/hostapd# iw wlan0 set txpower fixed 10 >> command failed: Operation not supported (-95) > > iw uses mBm (millibels referenced to 1 milliwatt) rather than the more familiar dBm. > try: iw wlan0 set txpower fixed 1000 > >> 'iwconfig' seems to update the information that's displayed but it >> doesn't affect the actual tx power [..] >> Is there another way to set the tx power? I want to reduce the range >> of my AP and am trying to lower the tx power. > > see attached patch. But I have to add that it won't change the > txpower of frames which are generated by the MAC [like RTS/CTS and > (B)ACKS]. > > Best Regards and good night. > --- > diff --git a/drivers/net/wireless/ath/carl9170/tx.c b/drivers/net/wireless/ath/carl9170/tx.c > index d19a9ee..771e1a9 100644 > --- a/drivers/net/wireless/ath/carl9170/tx.c > +++ b/drivers/net/wireless/ath/carl9170/tx.c > @@ -719,6 +719,8 @@ static void carl9170_tx_rate_tpc_chains(struct ar9170 *ar, > else > *chains = AR9170_TX_PHY_TXCHAIN_2; > } > + > + *tpc = min_t(unsigned int, *tpc, ar->hw->conf.power_level * 2); > } > > static __le32 carl9170_tx_physet(struct ar9170 *ar, Christian, Thank you very much for this patch. I can now use 'iw' to set the transmit power. root@OpenWrt:/# iw wlan0 set txpower fixed 1000 - sets it to 10dBm root@OpenWrt:/# iw wlan0 set txpower fixed 100 - sets it to 1 dBm And I can see the difference in the transmitted packets. Do you have a suggestion on how to implement this in an older version of compat-wireless (specifically compat-wireless-2011-04-19)? This is because your beacon IE reordering suggestion from a few months back (http://marc.info/?l=linux-wireless&m=131643758607833&w=2 ) was critical in having a usable network. The tx.c file has changed considerably since then and I can't find the right place to apply tx power change. How do I change the carl9170/tx.c file from compat-wireless-2011-04-19 to support tx power control? It doesn't have the carl9170_tx_rate_tpc_chains() function. But it has a carl9170_tx_physet() function. Can I do something like power = min_t(unsigned int, *tpc, ar->hw->conf.power_level * 2); in this function after power <<= AR9170_TX_PHY_TX_PWR_S; power &= AR9170_TX_PHY_TX_PWR; but before tmp |= cpu_to_le32(power); Alternatively, can you suggest where do I apply your beacon IE reordering suggestion in a recent (e.g. from 2011-11-15) compat-wireless release? You had said: in net/mac80211/tx.c look for the NL80211_IFTYPE_AP case and move: if (beacon->tail) memcpy(skb_put(skb, beacon->tail_len), beacon->tail, beacon->tail_len); in front of if (local->tim_in_locked_section) { Thanks again for all your help. - Harshal -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
