mt76: usb: do not use sg buffers for mcu messages

Do not use scatter-gather buffers for mcu commands.
Introduce mt76u_buf_alloc and mt76u_buf_alloc_sg routines.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt76.h

@@ -87,6 +87,7 @@ struct mt76u_buf {
 	struct mt76_dev *dev;
 	struct urb *urb;
 	size_t len;
+	void *buf;
 	bool done;
 };
 
@@ -748,7 +749,7 @@ void mt76u_single_wr(struct mt76_dev *dev, const u8 req,
 int mt76u_init(struct mt76_dev *dev, struct usb_interface *intf);
 void mt76u_deinit(struct mt76_dev *dev);
 int mt76u_buf_alloc(struct mt76_dev *dev, struct mt76u_buf *buf,
-		    int nsgs, int len, int sglen, gfp_t gfp);
+		    int len, int data_len, gfp_t gfp);
 void mt76u_buf_free(struct mt76u_buf *buf);
 int mt76u_submit_buf(struct mt76_dev *dev, int dir, int index,
 		     struct mt76u_buf *buf, gfp_t gfp,

drivers/net/wireless/mediatek/mt76/mt76x02_usb_mcu.c

@@ -63,9 +63,9 @@ static int mt76x02u_mcu_wait_resp(struct mt76_dev *dev, u8 seq)
 	struct mt76_usb *usb = &dev->usb;
 	struct mt76u_buf *buf = &usb->mcu.res;
 	struct urb *urb = buf->urb;
+	u8 *data = buf->buf;
 	int i, ret;
 	u32 rxfce;
-	u8 *data;
 
 	for (i = 0; i < 5; i++) {
 		if (!wait_for_completion_timeout(&usb->mcu.cmpl,
@@ -75,7 +75,6 @@ static int mt76x02u_mcu_wait_resp(struct mt76_dev *dev, u8 seq)
 		if (urb->status)
 			return -EIO;
 
-		data = sg_virt(&urb->sg[0]);
 		if (usb->mcu.rp)
 			mt76x02u_multiple_mcu_reads(dev, data + 4,
 						    urb->actual_length - 8);

drivers/net/wireless/mediatek/mt76/usb.c

@@ -319,8 +319,9 @@ mt76u_fill_rx_sg(struct mt76_dev *dev, struct mt76u_buf *buf,
 	return i ? : -ENOMEM;
 }
 
-int mt76u_buf_alloc(struct mt76_dev *dev, struct mt76u_buf *buf,
-		    int nsgs, int len, int sglen, gfp_t gfp)
+static int
+mt76u_buf_alloc_sg(struct mt76_dev *dev, struct mt76u_buf *buf,
+		   int nsgs, int len, int sglen, gfp_t gfp)
 {
 	buf->urb = usb_alloc_urb(0, gfp);
 	if (!buf->urb)
@@ -337,6 +338,25 @@ int mt76u_buf_alloc(struct mt76_dev *dev, struct mt76u_buf *buf,
 	return mt76u_fill_rx_sg(dev, buf, nsgs, len, sglen);
 }
 
+int mt76u_buf_alloc(struct mt76_dev *dev, struct mt76u_buf *buf,
+		    int len, int data_len, gfp_t gfp)
+{
+	struct mt76_queue *q = &dev->q_rx[MT_RXQ_MAIN];
+
+	buf->urb = usb_alloc_urb(0, gfp);
+	if (!buf->urb)
+		return -ENOMEM;
+
+	buf->buf = page_frag_alloc(&q->rx_page, len, gfp);
+	if (!buf->buf)
+		return -ENOMEM;
+
+	buf->len = data_len;
+	buf->dev = dev;
+
+	return 0;
+}
+
 void mt76u_buf_free(struct mt76u_buf *buf)
 {
 	struct urb *urb = buf->urb;
@@ -350,6 +370,9 @@ void mt76u_buf_free(struct mt76u_buf *buf)
 
 		skb_free_frag(sg_virt(sg));
 	}
+	if (buf->buf)
+		skb_free_frag(buf->buf);
+
 	usb_free_urb(buf->urb);
 }
 EXPORT_SYMBOL_GPL(mt76u_buf_free);
@@ -360,6 +383,7 @@ int mt76u_submit_buf(struct mt76_dev *dev, int dir, int index,
 {
 	struct usb_interface *intf = to_usb_interface(dev->dev);
 	struct usb_device *udev = interface_to_usbdev(intf);
+	u8 *data = buf->urb->num_sgs ? NULL : buf->buf;
 	unsigned int pipe;
 
 	if (dir == USB_DIR_IN)
@@ -367,7 +391,7 @@ int mt76u_submit_buf(struct mt76_dev *dev, int dir, int index,
 	else
 		pipe = usb_sndbulkpipe(udev, dev->usb.out_ep[index]);
 
-	usb_fill_bulk_urb(buf->urb, udev, pipe, NULL, buf->len,
+	usb_fill_bulk_urb(buf->urb, udev, pipe, data, buf->len,
 			  complete_fn, context);
 	trace_submit_urb(dev, buf->urb);
 
@@ -555,10 +579,10 @@ static int mt76u_alloc_rx(struct mt76_dev *dev)
 
 	q->ndesc = MT_NUM_RX_ENTRIES;
 	for (i = 0; i < q->ndesc; i++) {
-		err = mt76u_buf_alloc(dev, &q->entry[i].ubuf,
-				      nsgs, q->buf_size,
-				      SKB_WITH_OVERHEAD(q->buf_size),
-				      GFP_KERNEL);
+		err = mt76u_buf_alloc_sg(dev, &q->entry[i].ubuf,
+					 nsgs, q->buf_size,
+					 SKB_WITH_OVERHEAD(q->buf_size),
+					 GFP_KERNEL);
 		if (err < 0)
 			return err;
 	}

drivers/net/wireless/mediatek/mt76/usb_mcu.c

@@ -29,9 +29,8 @@ int mt76u_mcu_init_rx(struct mt76_dev *dev)
 	struct mt76_usb *usb = &dev->usb;
 	int err;
 
-	err = mt76u_buf_alloc(dev, &usb->mcu.res, 1,
-			      MCU_RESP_URB_SIZE, MCU_RESP_URB_SIZE,
-			      GFP_KERNEL);
+	err = mt76u_buf_alloc(dev, &usb->mcu.res, MCU_RESP_URB_SIZE,
+			      MCU_RESP_URB_SIZE, GFP_KERNEL);
 	if (err < 0)
 		return err;