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From: Ivo van Doorn <>
To: John Linville <>
	"linux-wireless" <>
Subject: [PATCH 3/7] rt2x00: Align ieee80211 header to 4-byte boundary for PCI devices
Date: Sat, 8 Aug 2009 23:53:47 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Some hardware require the ieee80211 header to be aligned to a
4-byte boundary before mapping it to the DMA. Otherwise some
frames (like beacons) will not be send out correctly by the

Signed-off-by: Ivo van Doorn <>
 drivers/net/wireless/rt2x00/rt2x00queue.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.c b/drivers/net/wireless/rt2x00/rt2x00queue.c
index 65435c9..e67e339 100644
--- a/drivers/net/wireless/rt2x00/rt2x00queue.c
+++ b/drivers/net/wireless/rt2x00/rt2x00queue.c
@@ -453,9 +453,21 @@ int rt2x00queue_write_tx_frame(struct data_queue *queue, struct sk_buff *skb)
 			rt2x00crypto_tx_remove_iv(skb, &txdesc);
+	/*
+	 * When DMA allocation is required we should guarentee to the
+	 * driver that the DMA is aligned to a 4-byte boundary.
+	 * Aligning the header to this boundary can be done by calling
+	 * rt2x00queue_payload_align with the header length of 0.
+	 * However some drivers require L2 padding to pad the payload
+	 * rather then the header. This could be a requirement for
+	 * PCI and USB devices, while header alignment only is valid
+	 * for PCI devices.
+	 */
 	if (test_bit(DRIVER_REQUIRE_L2PAD, &queue->rt2x00dev->flags))
 		rt2x00queue_payload_align(entry->skb, true,
+	else if (test_bit(DRIVER_REQUIRE_DMA, &queue->rt2x00dev->flags))
+		rt2x00queue_payload_align(entry->skb, false, 0);
 	 * It could be possible that the queue was corrupted and this

  reply	other threads:[~2009-08-08 21:56 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-08 21:53 [PATCH 1/7] rt2x00: Remove usage of deprecated radio_enabled & IEEE80211_CONF_CHANGE_RADIO_ENABLED Ivo van Doorn
2009-08-08 21:53 ` [PATCH 2/7] rt2x00: Use IEEE80211_TX_CTL_MORE_FRAMES flag Ivo van Doorn
2009-08-08 21:53   ` Ivo van Doorn [this message]
2009-08-08 21:54     ` [PATCH 4/7] rt2x00: Fix quality houskeeping for software diversity Ivo van Doorn
2009-08-08 21:54       ` [PATCH 5/7] rt2x00: Fix rounding errors in RSSI average calculation Ivo van Doorn
2009-08-08 21:55         ` [PATCH 6/7] rt2x00: Fix for race condition while update beacon Ivo van Doorn
2009-08-08 21:55           ` [PATCH 7/7] [PATCH] rt2x00: FIF_PSPOLL filter flag support Ivo van Doorn

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