On 12/17/19 10:40 AM, Lorenzo Bianconi wrote:
>> This patch removes a mt76_wr_copy call from the beacon path to hw.
>> The skb which is used in this place gets therefore build with txwi
>> inside its data. For mt76 usb drivers, this saves one synchronuous
>> copy call over usb, which lets the beacon work complete faster.
>>
>> In mmio case, there is not enough headroom to put the txwi into the
>> skb, it is therefore using an additional mt76_wr_copy, which is fast
>> over mmio. Thanks Stanislaw for pointing this out.
>>
>> Signed-off-by: Markus Theil <markus.theil@xxxxxxxxxxxxx>
>> ---
>> .../wireless/mediatek/mt76/mt76x02_beacon.c | 20 +++++++++++++++----
>> 1 file changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c b/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
>> index 1c4bdf88f712..68a4f512319e 100644
>> --- a/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
>> +++ b/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
>> @@ -26,15 +26,27 @@ static int
>> mt76x02_write_beacon(struct mt76x02_dev *dev, int offset, struct sk_buff *skb)
>> {
>> int beacon_len = dev->beacon_ops->slot_size;
>> - struct mt76x02_txwi txwi;
>>
>> if (WARN_ON_ONCE(beacon_len < skb->len + sizeof(struct mt76x02_txwi)))
>> return -ENOSPC;
>>
>> - mt76x02_mac_write_txwi(dev, &txwi, skb, NULL, NULL, skb->len);
>> + /* USB devices already reserve enough skb headroom for txwi's. This
>> + * helps to save slow copies over USB.
>> + */
>> + if (mt76_is_usb(&dev->mt76)) {
>> + struct mt76x02_txwi *txwi;
>> +
>> + mt76_insert_hdr_pad(skb);
> Do we really need mt76_insert_hdr_pad? I think beacon header should be 4B
> aligned.
>
> Regards,
> Lorenzo
I can leave it out of course, but I don't know, if beacons from
mac80211 are always 4B aligned.
Regards,
Markus
>> + txwi = (struct mt76x02_txwi *)(skb->data - sizeof(*txwi));
>> + mt76x02_mac_write_txwi(dev, txwi, skb, NULL, NULL, skb->len);
>> + skb_push(skb, sizeof(*txwi));
>> + } else {
>> + struct mt76x02_txwi txwi;
>>
>> - mt76_wr_copy(dev, offset, &txwi, sizeof(txwi));
>> - offset += sizeof(txwi);
>> + mt76x02_mac_write_txwi(dev, &txwi, skb, NULL, NULL, skb->len);
>> + mt76_wr_copy(dev, offset, &txwi, sizeof(txwi));
>> + offset += sizeof(txwi);
>> + }
>>
>> mt76_wr_copy(dev, offset, skb->data, skb->len);
>> return 0;
>> --
>> 2.24.0
>>
