On Mon, Nov 12, 2012 at 12:11 PM, Javier Cardona <javier@xxxxxxxxxxx> wrote:
> Thomas,
>
> On Mon, Nov 12, 2012 at 10:38 AM, Thomas Pedersen <thomas@xxxxxxxxxxx> wrote:
>> Allow drivers to indicate their mactime is at RX completion and adjust
>> for this in mac80211. Based on similar code by Johannes Berg.
>>
>> Signed-off-by: Thomas Pedersen <thomas@xxxxxxxxxxx>
>> ---
>> include/net/mac80211.h | 4 ++++
>> net/mac80211/ibss.c | 29 +++++--------------------
>> net/mac80211/ieee80211_i.h | 9 ++++++++
>> net/mac80211/mesh_sync.c | 43 ++++++-------------------------------
>> net/mac80211/rx.c | 14 ++++++++++---
>> net/mac80211/util.c | 50 ++++++++++++++++++++++++++++++++++++++++++++
>> 6 files changed, 85 insertions(+), 64 deletions(-)
>>
>> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
>> index 00b7204..a2b9b52 100644
>> --- a/include/net/mac80211.h
>> +++ b/include/net/mac80211.h
>> @@ -704,6 +704,9 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info)
>> * field) is valid and contains the time the first symbol of the MPDU
>> * was received. This is useful in monitor mode and for proper IBSS
>> * merging.
>> + * @RX_FLAG_MACTIME_END: The timestamp passed in the RX status (@mactime
>> + * field) is valid and contains the time the last symbol of the MPDU
>> + * was received.
>
> So with this change, you are suggesting that drivers set at most *one*
> of RX_FLAG_MACTIME_MPDU (if they report mactime at the start of the
> frame) or RX_FLAG_MACTIME_END (at the end)? If so, at the risk of
> being too verbose, I would suggest to use
> RX_FLAG_MACTIME_MPDU_{START,END} or to mention this in the comment:
> "This flag should not be set with RX_FLAG_MACTIME_MPDU"
OK, I'll rename RX_FLAG_MACTIME_MDPU to RX_FLAG_MACTIME START in the v2 then.
>> * @RX_FLAG_SHORTPRE: Short preamble was used for this frame
>> * @RX_FLAG_HT: HT MCS was used and rate_idx is MCS index
>> * @RX_FLAG_40MHZ: HT40 (40 MHz) was used
>> @@ -748,6 +751,7 @@ enum mac80211_rx_flags {
>> RX_FLAG_AMPDU_IS_LAST = BIT(18),
>> RX_FLAG_AMPDU_DELIM_CRC_ERROR = BIT(19),
>> RX_FLAG_AMPDU_DELIM_CRC_KNOWN = BIT(20),
>> + RX_FLAG_MACTIME_END = BIT(21),
>> };
>>
>> /**
>> diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
>> index c7386b2..92500d8 100644
>> --- a/net/mac80211/ibss.c
>> +++ b/net/mac80211/ibss.c
>> @@ -543,30 +543,11 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
>> if (ether_addr_equal(cbss->bssid, sdata->u.ibss.bssid))
>> goto put_bss;
>>
>> - if (rx_status->flag & RX_FLAG_MACTIME_MPDU) {
>> - /*
>> - * For correct IBSS merging we need mactime; since mactime is
>> - * defined as the time the first data symbol of the frame hits
>> - * the PHY, and the timestamp of the beacon is defined as "the
>> - * time that the data symbol containing the first bit of the
>> - * timestamp is transmitted to the PHY plus the transmitting
>> - * STA's delays through its local PHY from the MAC-PHY
>> - * interface to its interface with the WM" (802.11 11.1.2)
>> - * - equals the time this bit arrives at the receiver - we have
>> - * to take into account the offset between the two.
>> - *
>> - * E.g. at 1 MBit that means mactime is 192 usec earlier
>> - * (=24 bytes * 8 usecs/byte) than the beacon timestamp.
>> - */
>> - int rate;
>> -
>> - if (rx_status->flag & RX_FLAG_HT)
>> - rate = 65; /* TODO: HT rates */
>
> Ah, and I see that in your proposed
> ieee80211_calculate_rx_timestamp() you take care of HT rates... nice.
>
>> - else
>> - rate = local->hw.wiphy->bands[band]->
>> - bitrates[rx_status->rate_idx].bitrate;
>> -
>> - rx_timestamp = rx_status->mactime + (24 * 8 * 10 / rate);
>> + if (ieee80211_have_rx_timestamp(rx_status)) {
>> + /* time when timestamp field was received */
>> + rx_timestamp =
>> + ieee80211_calculate_rx_timestamp(local, rx_status,
>> + len + 4, 24);
>> } else {
>> /*
>> * second best option: get current TSF
>> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
>> index 3026519..6162342 100644
>> --- a/net/mac80211/ieee80211_i.h
>> +++ b/net/mac80211/ieee80211_i.h
>> @@ -1251,7 +1251,16 @@ static inline int ieee80211_bssid_match(const u8 *raddr, const u8 *addr)
>> is_broadcast_ether_addr(raddr);
>> }
>>
>> +static inline bool
>> +ieee80211_have_rx_timestamp(struct ieee80211_rx_status *status)
>> +{
>
> Maybe...
>
> WARN_ON((status->flag & RX_FLAG_MACTIME_MPDU) &&
> (status->flag & RX_FLAG_MACTIME_END)) ?
>
OK.
Thomas
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