On 07/28/2015 08:27 PM, Krishna Chaitanya wrote: > On Tue, Jul 28, 2015 at 10:42 PM, Grumbach, Emmanuel > <emmanuel.grumbach@xxxxxxxxx> wrote: >> >> On 07/28/2015 02:35 PM, Grumbach, Emmanuel wrote: >>>> On Tue, Jul 21, 2015 at 1:12 AM, Emmanuel Grumbach >>>> <emmanuel.grumbach@xxxxxxxxx> wrote: >>>>> diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c index >>>>> c8ba2e7..a758eb84 100644 >>>>> --- a/net/mac80211/agg-tx.c >>>>> +++ b/net/mac80211/agg-tx.c >>>>> @@ -97,7 +97,8 @@ static void ieee80211_send_addba_request(struct >>>> ieee80211_sub_if_data *sdata, >>>>> mgmt->u.action.u.addba_req.action_code = >>>>> WLAN_ACTION_ADDBA_REQ; >>>>> >>>>> mgmt->u.action.u.addba_req.dialog_token = dialog_token; >>>>> - capab = (u16)(1 << 1); /* bit 1 aggregation policy */ >>>>> + capab = (u16)(1 << 0); /* bit 0 A-MSDU support */ >>>> Shouldn't this be based on HW capability? We can add couple of more _HW_ >>>> flags for TX and RX and populate this based on that? >>> Why? >>> What will happen if we ask for A-MSDU inside A-MPDU and we won't do A-MSDU? >>> Worst case, the AP will deny this and will clear that bit in its response. >> I feel that my response was accurate, but the wording wasn't precise enough. >> We have two possibilities: >> 1) the AP does support A-MSDU in A-MPDU >> 2) the AP does not support A-MSDU in A-MPDU >> >> In the first case, the AP will reply with that bit set and the client >> can choose to send A-MSDU or not. I don't think that the AP needs to >> allocate anything special to support A-MSDU in A-MPDU, so it is free to ask. > AP needs to allocate large RX buffers to accomodate AMSDU + AMPDU, no? >> In the second case, the AP will reply with that same bit clear in the >> AddBA response, and mac0211 / driver will know not to send A-MSDU in >> A-MPDU (which the driver doesn't support in the case you were describing >> - so this is a no-op). >> The only concern you may have is about APs that would decline the AddBA >> request because of that bit. That doesn't seem to happen since a lot of >> vendors use A-MSDU in A-MPDU. > I understand from AP point of view, but what about the local HW? Don't we need > HW support to handle this A-MSDU in AMPDU? (or) the driver should handle this > support in ampdu_action based on the amsdu flag? > Depends on the HW design. But even if a device does not support it, then nothing bad will happen. mac80211 will request A-MSDU in A-MDPU and that specific device simply won't ever use that capability. -- 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
