Re: [ath9k-devel] Patching ath9k/mac80211 to change MAC layer features

From: Mohammed Shafi
Date: Mon Jun 20 2011 - 04:15:48 EST

On Fri, Jun 17, 2011 at 2:09 AM, Fred Matthews <fredmm@xxxxxxxxxxxxx> wrote:
> Hello all,
> I have a query regarding patching ath9k/mac80211 to change MAC layer
> features and I would be most grateful if someone can assist.
> I need to patch ath9k so that I can be able to modify/fix the A-MPDU
> aggregation frame length and other parameters such that they can be
> configured at runtime via debugfs. I made a newbie attempt at trying to
> change the aggregate length (attached), but I am unsure of the
> correctness/efficiency  - when applied throughput varies with different
> frame lengths entered but I can't be sure if its actually changing the
> aggregation length (passes the framelen/aggr_limit). Hence I would be very
> grateful if someone can assist in the correct way of doing this (possibly
> directly via mac80211).
> Also if the ampdu aggregate length is changed I believe the number/length of
> the subframes of the aggregate stays constant (at the default which is
> 32). I try to change this in my patch as well as the maximum software
> retries by just changing the default definition in ath9k.h, thus is there a
> (more) correct/better way of changing these. Finally, how can I patch the
> driver to be able to disable Block-Acks/aggregation via debugfs or
> otherwise.

to disable aggregation in the driver, please try this
diff --git a/drivers/net/wireless/ath/ath9k/init.c
index d4b166c..e0175d0 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -524,8 +524,6 @@ static void ath9k_init_misc(struct ath_softc *sc)
sc->config.txpowlimit = ATH_TXPOWER_MAX;

if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_HT) {
- sc->sc_flags |= SC_OP_TXAGGR;
- sc->sc_flags |= SC_OP_RXAGGR;

common->tx_chainmask = sc->sc_ah->caps.tx_chainmask;

if you want only tx-aggregation to be disabled , please comment out only that.
also you can completely disable HT by
diff --git a/drivers/net/wireless/ath/ath9k/hw.c
index 6de2655..696b4cc 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1915,10 +1915,7 @@ int ath9k_hw_fill_cap_info(struct ath_hw *ah)

common->crypt_caps |= ATH_CRYPT_CAP_CIPHER_AESCCM;

- if (ah->hw_version.devid != AR2427_DEVID_PCIE)
- pCap->hw_caps |= ATH9K_HW_CAP_HT;
- else
- pCap->hw_caps &= ~ATH9K_HW_CAP_HT;
+ pCap->hw_caps &= ~ATH9K_HW_CAP_HT;

if (AR_SREV_9271(ah))
pCap->num_gpio_pins = AR9271_NUM_GPIO;

> I highly appreciate, help in any of the above, as well as other advice,
> Many thanks
> _______________________________________________
> ath9k-devel mailing list
> ath9k-devel@xxxxxxxxxxxxxxx

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