| Message ID | 20210211161830.17366-3-TheSven73@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | lan743x speed boost | expand |
Hi Sven, see below. > + if (buffer_info->dma_ptr) { > + /* unmap from dma */ > + packet_length = RX_DESC_DATA0_FRAME_LENGTH_GET_ > + (le32_to_cpu(descriptor->data0)); > + if (packet_length == 0 || > + packet_length > buffer_info->buffer_length) > + /* buffer is part of multi-buffer packet: fully used */ > + packet_length = buffer_info->buffer_length; According to the document I have, FRAME_LENGTH is only valid when LS bit is set, and reserved otherwise. Therefore, I'm not sure you can rely on it being zero when LS is not set, even if your experiments say it is. Future chip revisions might use those bits differently. Can you change this so the LS bit is checked. If set you can use the smaller of FRAME_LENGTH or buffer length. If clear you can just use buffer length. > + /* sync used part of buffer only */ > + dma_sync_single_for_cpu(dev, buffer_info->dma_ptr, > + packet_length, > + DMA_FROM_DEVICE); > + dma_unmap_single_attrs(dev, buffer_info->dma_ptr, > + buffer_info->buffer_length, > + DMA_FROM_DEVICE, > + DMA_ATTR_SKIP_CPU_SYNC); > + }
Hi Bryan, On Fri, Feb 12, 2021 at 3:45 PM <Bryan.Whitehead@microchip.com> wrote: > > According to the document I have, FRAME_LENGTH is only valid when LS bit is set, and reserved otherwise. > Therefore, I'm not sure you can rely on it being zero when LS is not set, even if your experiments say it is. > Future chip revisions might use those bits differently. That's good to know. I didn't find any documentation related to multi-buffer frames, so I had to go with what I saw the chip do experimentally. It's great that you were able to double-check against the official docs. > > Can you change this so the LS bit is checked. > If set you can use the smaller of FRAME_LENGTH or buffer length. > If clear you can just use buffer length. Will do. Are you planning to hold off your tests until v3? It shouldn't take too long.
> Will do. Are you planning to hold off your tests until v3? It shouldn't take too > long. Sure, we will wait for v3
diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c index 0c48bb559719..36cc67c72851 100644 --- a/drivers/net/ethernet/microchip/lan743x_main.c +++ b/drivers/net/ethernet/microchip/lan743x_main.c @@ -1968,35 +1968,49 @@ static int lan743x_rx_init_ring_element(struct lan743x_rx *rx, int index) struct net_device *netdev = rx->adapter->netdev; struct device *dev = &rx->adapter->pdev->dev; struct lan743x_rx_buffer_info *buffer_info; + unsigned int buffer_length, packet_length; struct lan743x_rx_descriptor *descriptor; struct sk_buff *skb; dma_addr_t dma_ptr; - int length; - length = netdev->mtu + ETH_HLEN + 4 + RX_HEAD_PADDING; + buffer_length = netdev->mtu + ETH_HLEN + 4 + RX_HEAD_PADDING; descriptor = &rx->ring_cpu_ptr[index]; buffer_info = &rx->buffer_info[index]; - skb = __netdev_alloc_skb(netdev, length, GFP_ATOMIC | GFP_DMA); + skb = __netdev_alloc_skb(netdev, buffer_length, GFP_ATOMIC | GFP_DMA); if (!skb) return -ENOMEM; - dma_ptr = dma_map_single(dev, skb->data, length, DMA_FROM_DEVICE); + dma_ptr = dma_map_single(dev, skb->data, buffer_length, DMA_FROM_DEVICE); if (dma_mapping_error(dev, dma_ptr)) { dev_kfree_skb_any(skb); return -ENOMEM; } - if (buffer_info->dma_ptr) - dma_unmap_single(dev, buffer_info->dma_ptr, - buffer_info->buffer_length, DMA_FROM_DEVICE); + if (buffer_info->dma_ptr) { + /* unmap from dma */ + packet_length = RX_DESC_DATA0_FRAME_LENGTH_GET_ + (le32_to_cpu(descriptor->data0)); + if (packet_length == 0 || + packet_length > buffer_info->buffer_length) + /* buffer is part of multi-buffer packet: fully used */ + packet_length = buffer_info->buffer_length; + /* sync used part of buffer only */ + dma_sync_single_for_cpu(dev, buffer_info->dma_ptr, + packet_length, + DMA_FROM_DEVICE); + dma_unmap_single_attrs(dev, buffer_info->dma_ptr, + buffer_info->buffer_length, + DMA_FROM_DEVICE, + DMA_ATTR_SKIP_CPU_SYNC); + } buffer_info->skb = skb; buffer_info->dma_ptr = dma_ptr; - buffer_info->buffer_length = length; + buffer_info->buffer_length = buffer_length; descriptor->data1 = cpu_to_le32(DMA_ADDR_LOW32(buffer_info->dma_ptr)); descriptor->data2 = cpu_to_le32(DMA_ADDR_HIGH32(buffer_info->dma_ptr)); descriptor->data3 = 0; descriptor->data0 = cpu_to_le32((RX_DESC_DATA0_OWN_ | - (length & RX_DESC_DATA0_BUF_LENGTH_MASK_))); + (buffer_length & RX_DESC_DATA0_BUF_LENGTH_MASK_))); lan743x_rx_update_tail(rx, index); return 0;