Commit ab365c33 authored by Andre Przywara's avatar Andre Przywara Committed by David S. Miller
Browse files

net: axienet: Factor out TX descriptor chain cleanup 



Factor out the code that cleans up a number of connected TX descriptors,
as we will need it to properly roll back a failed _xmit() call.
There are subtle differences between cleaning up a successfully sent
chain (unknown number of involved descriptors, total data size needed)
and a chain that was about to set up (number of descriptors known), so
cater for those variations with some extra parameters.

Signed-off-by: default avatarAndre Przywara <andre.przywara@arm.com>
Reviewed-by: default avatarRadhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e7fea0b9

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

+57 −22
Original line number Diff line number Diff line
@@ -545,32 +545,46 @@ static int axienet_device_reset(struct net_device *ndev) 
}



/**

 * axienet_start_xmit_done - Invoked once a transmit is completed by the

 * Axi DMA Tx channel.

 * axienet_free_tx_chain - Clean up a series of linked TX descriptors.

 * @ndev:	Pointer to the net_device structure

 * @first_bd:	Index of first descriptor to clean up

 * @nr_bds:	Number of descriptors to clean up, can be -1 if unknown.

 * @sizep:	Pointer to a u32 filled with the total sum of all bytes

 * 		in all cleaned-up descriptors. Ignored if NULL.

 *

 * This function is invoked from the Axi DMA Tx isr to notify the completion

 * of transmit operation. It clears fields in the corresponding Tx BDs and

 * unmaps the corresponding buffer so that CPU can regain ownership of the

 * buffer. It finally invokes "netif_wake_queue" to restart transmission if

 * required.

 * Would either be called after a successful transmit operation, or after

 * there was an error when setting up the chain.

 * Returns the number of descriptors handled.

 */

static void axienet_start_xmit_done(struct net_device *ndev)

static int axienet_free_tx_chain(struct net_device *ndev, u32 first_bd,

				 int nr_bds, u32 *sizep)

{

	u32 size = 0;

	u32 packets = 0;

	struct axienet_local *lp = netdev_priv(ndev);

	struct axidma_bd *cur_p;

	unsigned int status = 0;

	int max_bds = nr_bds;

	unsigned int status;

	int i;



	if (max_bds == -1)

		max_bds = lp->tx_bd_num;



	cur_p = &lp->tx_bd_v[lp->tx_bd_ci];

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

		cur_p = &lp->tx_bd_v[(first_bd + i) % lp->tx_bd_num];

		status = cur_p->status;

	while (status & XAXIDMA_BD_STS_COMPLETE_MASK) {



		/* If no number is given, clean up *all* descriptors that have

		 * been completed by the MAC.

		 */

		if (nr_bds == -1 && !(status & XAXIDMA_BD_STS_COMPLETE_MASK))

			break;



		dma_unmap_single(ndev->dev.parent, cur_p->phys,

				(cur_p->cntrl & XAXIDMA_BD_CTRL_LENGTH_MASK),

				DMA_TO_DEVICE);

		if (cur_p->skb)



		if (cur_p->skb && (status & XAXIDMA_BD_STS_COMPLETE_MASK))

			dev_consume_skb_irq(cur_p->skb);



		cur_p->cntrl = 0;

		cur_p->app0 = 0;

		cur_p->app1 = 0;
@@ -579,15 +593,36 @@ static void axienet_start_xmit_done(struct net_device *ndev) 
		cur_p->status = 0;

		cur_p->skb = NULL;



		size += status & XAXIDMA_BD_STS_ACTUAL_LEN_MASK;

		packets++;

		if (sizep)

			*sizep += status & XAXIDMA_BD_STS_ACTUAL_LEN_MASK;

	}



		if (++lp->tx_bd_ci >= lp->tx_bd_num)

			lp->tx_bd_ci = 0;

		cur_p = &lp->tx_bd_v[lp->tx_bd_ci];

		status = cur_p->status;

	return i;

}



/**

 * axienet_start_xmit_done - Invoked once a transmit is completed by the

 * Axi DMA Tx channel.

 * @ndev:	Pointer to the net_device structure

 *

 * This function is invoked from the Axi DMA Tx isr to notify the completion

 * of transmit operation. It clears fields in the corresponding Tx BDs and

 * unmaps the corresponding buffer so that CPU can regain ownership of the

 * buffer. It finally invokes "netif_wake_queue" to restart transmission if

 * required.

 */

static void axienet_start_xmit_done(struct net_device *ndev)

{

	struct axienet_local *lp = netdev_priv(ndev);

	u32 packets = 0;

	u32 size = 0;



	packets = axienet_free_tx_chain(ndev, lp->tx_bd_ci, -1, &size);



	lp->tx_bd_ci += packets;

	if (lp->tx_bd_ci >= lp->tx_bd_num)

		lp->tx_bd_ci -= lp->tx_bd_num;



	ndev->stats.tx_packets += packets;

	ndev->stats.tx_bytes += size;

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