Re: [PATCH 1/2] mac80211: add flag to indicate HW only Tx-agg support

On Thu, Aug 25, 2011 at 15:18, Helmut Schaa [off-list ref] wrote:

Hi,

On Thu, Aug 25, 2011 at 11:51 AM, Arik Nemtsov [off-list ref] wrote:

quoted

When this flag is set, Tx aggregations will not be initiated even
if the hardware supports A-MPDU aggregation in general. This flag
is required for devices supporting (partial) software Rx-aggregation.

Is the hardware unable to do TX aggregation?
Or is it just not implemented?
Or is it entirely done in hw?

Tx aggregations are done entirely in HW.

Instead of cluttering mac80211 with hw flags you could also just disallow tx
aggregation sessions in the ampdu_action callback in the driver.

Well the driver is doing some pretty heavy lifting before even calling
the ampdu_action callback. Namely, ieee80211_start_tx_ba_session()
doesn't call it. AFAICT, the return from the callback is only used as
an indication that Tx BA session are temporary unavailable, and
mac80211 should try again. This is not the case here.

Regards,
Arik