iwlwifi: mvm: program DTIM timings properly

For the firmware to know when DTIM beacons arrive
we have to program the DTIM time in TSF and system
time in the MAC context. Since mac80211 now tracks
the different times (on demand), this becomes easy.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 35 insertions, 2 deletions

diff --git a/drivers/net/wireless/iwlwifi/mvm/mac-ctxt.c b/drivers/net/wireless/iwlwifi/mvm/mac-ctxt.c
index 0854dc338881..c33bec83b807 100644
--- a/drivers/net/wireless/iwlwifi/mvm/mac-ctxt.c
+++ b/drivers/net/wireless/iwlwifi/mvm/mac-ctxt.c
@@ -585,10 +585,43 @@ static void iwl_mvm_mac_ctxt_cmd_fill_sta(struct iwl_mvm *mvm,
                                           struct iwl_mac_data_sta *ctxt_sta)
 {
         /* We need the dtim_period to set the MAC as associated */
-        if (vif->bss_conf.assoc && vif->bss_conf.dtim_period)
+        if (vif->bss_conf.assoc && vif->bss_conf.dtim_period) {
+                u32 dtim_offs;
+
+                /*
+                 * The DTIM count counts down, so when it is N that means N
+                 * more beacon intervals happen until the DTIM TBTT. Therefore
+                 * add this to the current time. If that ends up being in the
+                 * future, the firmware will handle it.
+                 *
+                 * Also note that the system_timestamp (which we get here as
+                 * "sync_device_ts") and TSF timestamp aren't at exactly the
+                 * same offset in the frame -- the TSF is at the first symbol
+                 * of the TSF, the system timestamp is at signal acquisition
+                 * time. This means there's an offset between them of at most
+                 * a few hundred microseconds (24 * 8 bits + PLCP time gives
+                 * 384us in the longest case), this is currently not relevant
+                 * as the firmware wakes up around 2ms before the TBTT.
+                 */
+                dtim_offs = vif->bss_conf.sync_dtim_count *
+                                vif->bss_conf.beacon_int;
+                /* convert TU to usecs */
+                dtim_offs *= 1024;
+
+                ctxt_sta->dtim_tsf =
+                        cpu_to_le64(vif->bss_conf.sync_tsf + dtim_offs);
+                ctxt_sta->dtim_time =
+                        cpu_to_le32(vif->bss_conf.sync_device_ts + dtim_offs);
+
+                IWL_DEBUG_INFO(mvm, "DTIM TBTT is 0x%llx/0x%x, offset %d\n",
+                               le64_to_cpu(ctxt_sta->dtim_tsf),
+                               le32_to_cpu(ctxt_sta->dtim_time),
+                               dtim_offs);
+
                 ctxt_sta->is_assoc = cpu_to_le32(1);
-        else
+        } else {
                 ctxt_sta->is_assoc = cpu_to_le32(0);
+        }
 
         ctxt_sta->bi = cpu_to_le32(vif->bss_conf.beacon_int);
         ctxt_sta->bi_reciprocal =