Commit 4bd437ea authored by Christian Lamparter's avatar Christian Lamparter Committed by John W. Linville
Browse files

carl9170: revamp carl9170_tx_prepare 



David Miller complained about the driver's excessive use
of variables in __packed structs. While I did not fully
agree with his sole "performance" argument on all accounts.
I do see some room for improvement in hot-paths on
architectures without an efficient access to unaligned
elements.

This first patch (dare I say?) optimizes an important tx
hot-path in the driver: carl9170_tx_prepare.

Signed-off-by: default avatarChristian Lamparter <chunkeey@googlemail.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 9c655c8b

drivers/net/wireless/ath/carl9170/tx.c

+75 −80
Original line number Diff line number Diff line
@@ -760,8 +760,8 @@ static int carl9170_tx_prepare(struct ar9170 *ar, struct sk_buff *skb) 
	struct carl9170_tx_info *arinfo;

	unsigned int hw_queue;

	int i;

	u16 keytype = 0;

	u16 len, icv = 0;

	__le16 mac_tmp;

	u16 len;

	bool ampdu, no_ack;



	BUILD_BUG_ON(sizeof(*arinfo) > sizeof(info->rate_driver_data));
@@ -773,6 +773,10 @@ static int carl9170_tx_prepare(struct ar9170 *ar, struct sk_buff *skb) 


	BUILD_BUG_ON(IEEE80211_TX_MAX_RATES < CARL9170_TX_MAX_RATES);



	BUILD_BUG_ON(AR9170_MAX_VIRTUAL_MAC >

		((CARL9170_TX_SUPER_MISC_VIF_ID >>

		 CARL9170_TX_SUPER_MISC_VIF_ID_S) + 1));



	hw_queue = ar9170_qmap[carl9170_get_queue(ar, skb)];



	hdr = (void *)skb->data;
@@ -793,20 +797,37 @@ static int carl9170_tx_prepare(struct ar9170 *ar, struct sk_buff *skb) 
	txc = (void *)skb_push(skb, sizeof(*txc));

	memset(txc, 0, sizeof(*txc));



	ampdu = !!(info->flags & IEEE80211_TX_CTL_AMPDU);

	SET_VAL(CARL9170_TX_SUPER_MISC_QUEUE, txc->s.misc, hw_queue);



	if (likely(cvif))

		SET_VAL(CARL9170_TX_SUPER_MISC_VIF_ID, txc->s.misc, cvif->id);



	if (unlikely(info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM))

		txc->s.misc |= CARL9170_TX_SUPER_MISC_CAB;



	if (unlikely(ieee80211_is_probe_resp(hdr->frame_control)))

		txc->s.misc |= CARL9170_TX_SUPER_MISC_FILL_IN_TSF;



	mac_tmp = cpu_to_le16(AR9170_TX_MAC_HW_DURATION |

			      AR9170_TX_MAC_BACKOFF);

	mac_tmp |= cpu_to_le16((hw_queue << AR9170_TX_MAC_QOS_S) &&

			       AR9170_TX_MAC_QOS);



	no_ack = !!(info->flags & IEEE80211_TX_CTL_NO_ACK);

	if (unlikely(no_ack))

		mac_tmp |= cpu_to_le16(AR9170_TX_MAC_NO_ACK);



	if (info->control.hw_key) {

		icv = info->control.hw_key->icv_len;

		len += info->control.hw_key->icv_len;



		switch (info->control.hw_key->cipher) {

		case WLAN_CIPHER_SUITE_WEP40:

		case WLAN_CIPHER_SUITE_WEP104:

		case WLAN_CIPHER_SUITE_TKIP:

			keytype = AR9170_TX_MAC_ENCR_RC4;

			mac_tmp |= cpu_to_le16(AR9170_TX_MAC_ENCR_RC4);

			break;

		case WLAN_CIPHER_SUITE_CCMP:

			keytype = AR9170_TX_MAC_ENCR_AES;

			mac_tmp |= cpu_to_le16(AR9170_TX_MAC_ENCR_AES);

			break;

		default:

			WARN_ON(1);
@@ -814,48 +835,58 @@ static int carl9170_tx_prepare(struct ar9170 *ar, struct sk_buff *skb) 
		}

	}



	BUILD_BUG_ON(AR9170_MAX_VIRTUAL_MAC >

		((CARL9170_TX_SUPER_MISC_VIF_ID >>

		 CARL9170_TX_SUPER_MISC_VIF_ID_S) + 1));



	txc->s.len = cpu_to_le16(len + sizeof(*txc));

	txc->f.length = cpu_to_le16(len + icv + 4);

	SET_VAL(CARL9170_TX_SUPER_MISC_VIF_ID, txc->s.misc,

		cvif ? cvif->id : 0);

	ampdu = !!(info->flags & IEEE80211_TX_CTL_AMPDU);

	if (ampdu) {

		unsigned int density, factor;



	txc->f.mac_control = cpu_to_le16(AR9170_TX_MAC_HW_DURATION |

					 AR9170_TX_MAC_BACKOFF);

		if (unlikely(!sta || !cvif))

			goto err_out;



	SET_VAL(CARL9170_TX_SUPER_MISC_QUEUE, txc->s.misc, hw_queue);

		factor = min_t(unsigned int, 1u,

			 info->control.sta->ht_cap.ampdu_factor);



	txc->f.mac_control |= cpu_to_le16(hw_queue << AR9170_TX_MAC_QOS_S);

	txc->f.mac_control |= cpu_to_le16(keytype);

	txc->f.phy_control = cpu_to_le32(0);

		density = info->control.sta->ht_cap.ampdu_density;



	if (no_ack)

		txc->f.mac_control |= cpu_to_le16(AR9170_TX_MAC_NO_ACK);

		if (density) {

			/*

			 * Watch out!

			 *

			 * Otus uses slightly different density values than

			 * those from the 802.11n spec.

			 */



	if (info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM)

		txc->s.misc |= CARL9170_TX_SUPER_MISC_CAB;

			density = max_t(unsigned int, density + 1, 7u);

		}



	txrate = &info->control.rates[0];

	if (carl9170_tx_rts_check(ar, txrate, ampdu, no_ack))

		txc->f.mac_control |= cpu_to_le16(AR9170_TX_MAC_PROT_RTS);

	else if (carl9170_tx_cts_check(ar, txrate))

		txc->f.mac_control |= cpu_to_le16(AR9170_TX_MAC_PROT_CTS);

		SET_VAL(CARL9170_TX_SUPER_AMPDU_DENSITY,

			txc->s.ampdu_settings, density);



	SET_VAL(CARL9170_TX_SUPER_RI_TRIES, txc->s.ri[0], txrate->count);

	txc->f.phy_control |= carl9170_tx_physet(ar, info, txrate);

		SET_VAL(CARL9170_TX_SUPER_AMPDU_FACTOR,

			txc->s.ampdu_settings, factor);



	if (info->flags & IEEE80211_TX_CTL_AMPDU) {

		for (i = 1; i < CARL9170_TX_MAX_RATES; i++) {

		for (i = 0; i < CARL9170_TX_MAX_RATES; i++) {

			txrate = &info->control.rates[i];

			if (txrate->idx >= 0)

			if (txrate->idx >= 0) {

				txc->s.ri[i] =

					CARL9170_TX_SUPER_RI_AMPDU;



				if (WARN_ON(!(txrate->flags &

					      IEEE80211_TX_RC_MCS))) {

					/*

					 * Not sure if it's even possible

					 * to aggregate non-ht rates with

					 * this HW.

					 */

					goto err_out;

				}

				continue;

			}



			txrate->idx = 0;

			txrate->count = ar->hw->max_rate_tries;

		}



		mac_tmp |= cpu_to_le16(AR9170_TX_MAC_AGGR);

	}



	/*
@@ -878,57 +909,21 @@ static int carl9170_tx_prepare(struct ar9170 *ar, struct sk_buff *skb) 
			txc->s.ri[i] |= (AR9170_TX_MAC_PROT_CTS <<

				CARL9170_TX_SUPER_RI_ERP_PROT_S);



		/*

		 * unaggregated fallback, in case aggregation

		 * proves to be unsuccessful and unreliable.

		 */

		if (ampdu && i < 3)

			txc->s.ri[i] |= CARL9170_TX_SUPER_RI_AMPDU;



		txc->s.rr[i - 1] = carl9170_tx_physet(ar, info, txrate);

	}



	if (ieee80211_is_probe_resp(hdr->frame_control))

		txc->s.misc |= CARL9170_TX_SUPER_MISC_FILL_IN_TSF;



	if (ampdu) {

		unsigned int density, factor;



		if (unlikely(!sta || !cvif))

			goto err_out;



		density = info->control.sta->ht_cap.ampdu_density;

		factor = info->control.sta->ht_cap.ampdu_factor;



		if (density) {

			/*

			 * Watch out!

			 *

			 * Otus uses slightly different density values than

			 * those from the 802.11n spec.

			 */



			density = max_t(unsigned int, density + 1, 7u);

		}



		factor = min_t(unsigned int, 1u, factor);



		SET_VAL(CARL9170_TX_SUPER_AMPDU_DENSITY,

			txc->s.ampdu_settings, density);

	txrate = &info->control.rates[0];

	SET_VAL(CARL9170_TX_SUPER_RI_TRIES, txc->s.ri[0], txrate->count);



		SET_VAL(CARL9170_TX_SUPER_AMPDU_FACTOR,

			txc->s.ampdu_settings, factor);

	if (carl9170_tx_rts_check(ar, txrate, ampdu, no_ack))

		mac_tmp |= cpu_to_le16(AR9170_TX_MAC_PROT_RTS);

	else if (carl9170_tx_cts_check(ar, txrate))

		mac_tmp |= cpu_to_le16(AR9170_TX_MAC_PROT_CTS);



		if (info->control.rates[0].flags & IEEE80211_TX_RC_MCS) {

			txc->f.mac_control |= cpu_to_le16(AR9170_TX_MAC_AGGR);

		} else {

			/*

			 * Not sure if it's even possible to aggregate

			 * non-ht rates with this HW.

			 */

			WARN_ON_ONCE(1);

		}

	}

	txc->s.len = cpu_to_le16(skb->len);

	txc->f.length = cpu_to_le16(len + FCS_LEN);

	txc->f.mac_control = mac_tmp;

	txc->f.phy_control = carl9170_tx_physet(ar, info, txrate);



	arinfo = (void *)info->rate_driver_data;

	arinfo->timeout = jiffies;

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