From: Vasanth Sadhasivan <vasanth.sadhasivan@xxxxxxxxxxx>
DMA allocated buffers are a precious resource. If there is no need for DMA
allocations, then it might be worth to use non-dma allocated buffers.
After testing the gs_usb driver with and without DMA allocation, there
does not seem to be a significant change in latency or cpu utilization
either way. Therefore, DMA allocation is not necessary and removed.
Co-developed-by: Rhett Aultman <rhett.aultman@xxxxxxxxxxx>
Signed-off-by: Rhett Aultman <rhett.aultman@xxxxxxxxxxx>
Signed-off-by: Vasanth Sadhasivan <vasanth.sadhasivan@xxxxxxxxxxx>
---
drivers/net/can/usb/gs_usb.c | 38 ++++++++++--------------------------
1 file changed, 10 insertions(+), 28 deletions(-)
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index baf749c8cda3..1bfc775c62c5 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -269,7 +269,6 @@ struct gs_can {
struct usb_anchor tx_submitted;
atomic_t active_tx_urbs;
void *rxbuf[GS_MAX_RX_URBS];
- dma_addr_t rxbuf_dma[GS_MAX_RX_URBS];
};
/* usb interface struct */
@@ -587,9 +586,7 @@ static void gs_usb_xmit_callback(struct urb *urb)
if (urb->status)
netdev_info(netdev, "usb xmit fail %u\n", txc->echo_id);
-
- usb_free_coherent(urb->dev, urb->transfer_buffer_length,
- urb->transfer_buffer, urb->transfer_dma);
+ devm_kfree(&urb->dev->dev, urb->transfer_buffer);
}
static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
@@ -618,8 +615,7 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
if (!urb)
goto nomem_urb;
- hf = usb_alloc_coherent(dev->udev, dev->hf_size_tx, GFP_ATOMIC,
- &urb->transfer_dma);
+ hf = devm_kmalloc(&dev->udev->dev, dev->hf_size_tx, GFP_ATOMIC);
if (!hf) {
netdev_err(netdev, "No memory left for USB buffer\n");
goto nomem_hf;
@@ -663,7 +659,6 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
hf, dev->hf_size_tx,
gs_usb_xmit_callback, txc);
- urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
usb_anchor_urb(urb, &dev->tx_submitted);
can_put_echo_skb(skb, netdev, idx, 0);
@@ -678,8 +673,7 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
gs_free_tx_context(txc);
usb_unanchor_urb(urb);
- usb_free_coherent(dev->udev, urb->transfer_buffer_length,
- urb->transfer_buffer, urb->transfer_dma);
+ devm_kfree(&dev->udev->dev, hf);
if (rc == -ENODEV) {
netif_device_detach(netdev);
@@ -699,8 +693,7 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
return NETDEV_TX_OK;
badidx:
- usb_free_coherent(dev->udev, urb->transfer_buffer_length,
- urb->transfer_buffer, urb->transfer_dma);
+ devm_kfree(&dev->udev->dev, hf);
nomem_hf:
usb_free_urb(urb);
@@ -744,7 +737,6 @@ static int gs_can_open(struct net_device *netdev)
for (i = 0; i < GS_MAX_RX_URBS; i++) {
struct urb *urb;
u8 *buf;
- dma_addr_t buf_dma;
/* alloc rx urb */
urb = usb_alloc_urb(0, GFP_KERNEL);
@@ -752,10 +744,9 @@ static int gs_can_open(struct net_device *netdev)
return -ENOMEM;
/* alloc rx buffer */
- buf = usb_alloc_coherent(dev->udev,
- dev->parent->hf_size_rx,
- GFP_KERNEL,
- &buf_dma);
+ buf = devm_kmalloc(&dev->udev->dev,
+ dev->parent->hf_size_rx,
+ GFP_KERNEL);
if (!buf) {
netdev_err(netdev,
"No memory left for USB buffer\n");
@@ -763,8 +754,6 @@ static int gs_can_open(struct net_device *netdev)
return -ENOMEM;
}
- urb->transfer_dma = buf_dma;
-
/* fill, anchor, and submit rx urb */
usb_fill_bulk_urb(urb,
dev->udev,
@@ -773,7 +762,6 @@ static int gs_can_open(struct net_device *netdev)
buf,
dev->parent->hf_size_rx,
gs_usb_receive_bulk_callback, parent);
- urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
usb_anchor_urb(urb, &parent->rx_submitted);
@@ -786,16 +774,12 @@ static int gs_can_open(struct net_device *netdev)
"usb_submit failed (err=%d)\n", rc);
usb_unanchor_urb(urb);
- usb_free_coherent(dev->udev,
- sizeof(struct gs_host_frame),
- buf,
- buf_dma);
+ devm_kfree(&dev->udev->dev, buf);
usb_free_urb(urb);
break;
}
dev->rxbuf[i] = buf;
- dev->rxbuf_dma[i] = buf_dma;
/* Drop reference,
* USB core will take care of freeing it
@@ -863,10 +847,8 @@ static int gs_can_close(struct net_device *netdev)
if (!parent->active_channels) {
usb_kill_anchored_urbs(&parent->rx_submitted);
for (i = 0; i < GS_MAX_RX_URBS; i++)
- usb_free_coherent(dev->udev,
- sizeof(struct gs_host_frame),
- dev->rxbuf[i],
- dev->rxbuf_dma[i]);
+ devm_kfree(&dev->udev->dev,
+ dev->rxbuf[i]);
}
/* Stop sending URBs */
--
2.25.1
