Re: [PATCH 7/9] mac80211: add flags for STBC (Space-Time Block Coding)

[Felix Fietkau <nbd@openwrt.org>]

On 2010-04-19 10:59 AM, Johannes Berg wrote:
> On Mon, 2010-04-19 at 10:45 +0200, Felix Fietkau wrote:
>> On 2010-04-19 7:57 AM, Johannes Berg wrote:
>> > On Sun, 2010-04-18 at 18:05 +0200, Felix Fietkau wrote:
>> > 
>> >> >> + * @IEEE80211_TX_CTL_STBC: tells the driver to use Space-Time Block Coding
>> >> >> + *  (STBC) for this frame.
>> >> >>   */
>> >> >>  enum mac80211_tx_control_flags {
>> >> >>  	IEEE80211_TX_CTL_REQ_TX_STATUS		= BIT(0),
>> >> >> @@ -299,6 +301,7 @@ enum mac80211_tx_control_flags {
>> >> >>  	IEEE80211_TX_INTFL_HAS_RADIOTAP		= BIT(20),
>> >> >>  	IEEE80211_TX_INTFL_NL80211_FRAME_TX	= BIT(21),
>> >> >>  	IEEE80211_TX_CTL_LDPC			= BIT(22),
>> >> >> +	IEEE80211_TX_CTL_STBC			= BIT(23),
>> >> > 
>> >> > What if the # of streams is different? That doesn't look sufficient.
>> > 
>> >> Hm, you're right. I initially thought the combination of the MCS index
>> >> and the STBC flag would be enough, but there are still some corner cases.
>> > 
>> > Hm actually I guess that should be sufficient? What corner case are you
>> > thinking of?
>> Support for multi-rate retry and STBC with more than one stream on one
>> side, using rates from both MCS0-7 and MCS8-15 in the rate series.
>> Rx STBC for only one stream on the other side.
> 
> So the flag should be per rate entry instead, no?
Well, I think if we use two bits in the tx control flags, we don't need
it to be per rate entry.
We don't have any space left for more per rate entry flags ;)

- Felix