[PATCH v2 2/2] mt76: usb: do not always copy the first part of received frames

[Lorenzo Bianconi]

Set usb buffer size taking into account skb_shared_info in order to
not always copy the first part of received frames if A-MSDU is enabled
for SG capable devices

Signed-off-by: Lorenzo Bianconi <lore...@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt76.h |  3 +++
 drivers/net/wireless/mediatek/mt76/usb.c  | 12 ++++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h 
b/drivers/net/wireless/mediatek/mt76/mt76.h
index 74d4edf941d6..7899e9b88b54 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -32,6 +32,9 @@
 #define MT_RX_BUF_SIZE      2048
 #define MT_SKB_HEAD_LEN     128
 
+#define MT_BUF_WITH_OVERHEAD(x) \
+       ((x) + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
+
 struct mt76_dev;
 struct mt76_wcid;
 
diff --git a/drivers/net/wireless/mediatek/mt76/usb.c 
b/drivers/net/wireless/mediatek/mt76/usb.c
index 2bfc8214c0d8..5081643ce701 100644
--- a/drivers/net/wireless/mediatek/mt76/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/usb.c
@@ -286,7 +286,7 @@ static int
 mt76u_fill_rx_sg(struct mt76_dev *dev, struct mt76_queue *q, struct urb *urb,
                 int nsgs, gfp_t gfp)
 {
-       int i;
+       int i, data_size = SKB_WITH_OVERHEAD(q->buf_size);
 
        for (i = 0; i < nsgs; i++) {
                struct page *page;
@@ -299,7 +299,7 @@ mt76u_fill_rx_sg(struct mt76_dev *dev, struct mt76_queue 
*q, struct urb *urb,
 
                page = virt_to_head_page(data);
                offset = data - page_address(page);
-               sg_set_page(&urb->sg[i], page, q->buf_size, offset);
+               sg_set_page(&urb->sg[i], page, data_size, offset);
        }
 
        if (i < nsgs) {
@@ -311,7 +311,7 @@ mt76u_fill_rx_sg(struct mt76_dev *dev, struct mt76_queue 
*q, struct urb *urb,
        }
 
        urb->num_sgs = max_t(int, i, urb->num_sgs);
-       urb->transfer_buffer_length = urb->num_sgs * q->buf_size,
+       urb->transfer_buffer_length = urb->num_sgs * data_size;
        sg_init_marker(urb->sg, urb->num_sgs);
 
        return i ? : -ENOMEM;
@@ -611,8 +611,12 @@ static int mt76u_alloc_rx(struct mt76_dev *dev)
        if (!q->entry)
                return -ENOMEM;
 
-       q->buf_size = dev->usb.sg_en ? MT_RX_BUF_SIZE : PAGE_SIZE;
+       if (dev->usb.sg_en)
+               q->buf_size = MT_BUF_WITH_OVERHEAD(MT_RX_BUF_SIZE);
+       else
+               q->buf_size = PAGE_SIZE;
        q->ndesc = MT_NUM_RX_ENTRIES;
+
        for (i = 0; i < q->ndesc; i++) {
                err = mt76u_rx_urb_alloc(dev, &q->entry[i]);
                if (err < 0)
-- 
2.21.0