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Message-ID: <20231004135317.2b460acf@kernel.org> Date: Wed, 4 Oct 2023 13:53:17 -0700 From: Jakub Kicinski <kuba@...nel.org> To: Radhey Shyam Pandey <radhey.shyam.pandey@....com> Cc: <davem@...emloft.net>, <edumazet@...gle.com>, <pabeni@...hat.com>, <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>, <michal.simek@....com>, <linux@...linux.org.uk>, <f.fainelli@...il.com>, <netdev@...r.kernel.org>, <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>, <git@....com> Subject: Re: [PATCH net-next v7 3/3] net: axienet: Introduce dmaengine support On Thu, 28 Sep 2023 01:02:31 +0530 Radhey Shyam Pandey wrote: > +static int axienet_rx_submit_desc(struct net_device *ndev); can the forward declaration be avoided? > +/** > + * axienet_dma_tx_cb - DMA engine callback for TX channel. > + * @data: Pointer to the axienet_local structure. > + * @result: error reporting through dmaengine_result. > + * This function is called by dmaengine driver for TX channel to notify > + * that the transmit is done. > + */ > +static void axienet_dma_tx_cb(void *data, const struct dmaengine_result *result) > +{ > + struct axienet_local *lp = data; > + struct skbuf_dma_descriptor *skbuf_dma; > + > + skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_tail++); > + u64_stats_update_begin(&lp->tx_stat_sync); > + u64_stats_add(&lp->tx_bytes, skbuf_dma->skb->len); > + u64_stats_add(&lp->tx_packets, 1); > + u64_stats_update_end(&lp->tx_stat_sync); > + dma_unmap_sg(lp->dev, skbuf_dma->sgl, skbuf_dma->sg_len, DMA_TO_DEVICE); > + dev_kfree_skb_any(skbuf_dma->skb); dev_consume_skb_any(), kfree is for drops > +/** > + * axienet_start_xmit_dmaengine - Starts the transmission. > + * @skb: sk_buff pointer that contains data to be Txed. > + * @ndev: Pointer to net_device structure. > + * > + * Return: NETDEV_TX_OK on success or any non space errors. > + * NETDEV_TX_BUSY when free element in TX skb ring buffer > + * is not available. > + * > + * This function is invoked from xmit to initiate transmission. The > + * function sets the skbs, register dma call back API and submit > + * the dma transaction. > + * Additionally if checksum offloading is supported, > + * it populates AXI Stream Control fields with appropriate values. > + */ > +static netdev_tx_t > +axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev) > +{ > + struct dma_async_tx_descriptor *dma_tx_desc = NULL; > + struct axienet_local *lp = netdev_priv(ndev); > + struct skbuf_dma_descriptor *skbuf_dma; > + u32 app_metadata[DMA_NUM_APP_WORDS] = {0}; > + u32 csum_start_off; > + u32 csum_index_off; > + int sg_len; > + int ret; > + > + sg_len = skb_shinfo(skb)->nr_frags + 1; > + if (!CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX)) { > + netif_stop_queue(ndev); > + if (net_ratelimit()) > + netdev_warn(ndev, "TX ring unexpectedly full\n"); I don't see you stopping the queue when the ring gets full, am I not looking into the right place? Otherwise this is sort of expected to occasionally hapen > + return NETDEV_TX_BUSY; > + } > + > + skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_head); > + if (!skbuf_dma) > + return NETDEV_TX_OK; Leaks the skb? > + lp->tx_ring_head++; > + sg_init_table(skbuf_dma->sgl, sg_len); > + ret = skb_to_sgvec(skb, skbuf_dma->sgl, 0, skb->len); > + if (ret < 0) > + return NETDEV_TX_OK; > + > + ret = dma_map_sg(lp->dev, skbuf_dma->sgl, sg_len, DMA_TO_DEVICE); > + if (!ret) > + return NETDEV_TX_OK; > + > + /* Fill up app fields for checksum */ > + if (skb->ip_summed == CHECKSUM_PARTIAL) { > + if (lp->features & XAE_FEATURE_FULL_TX_CSUM) { > + /* Tx Full Checksum Offload Enabled */ > + app_metadata[0] |= 2; > + } else if (lp->features & XAE_FEATURE_PARTIAL_TX_CSUM) { > + csum_start_off = skb_transport_offset(skb); > + csum_index_off = csum_start_off + skb->csum_offset; > + /* Tx Partial Checksum Offload Enabled */ > + app_metadata[0] |= 1; > + app_metadata[1] = (csum_start_off << 16) | csum_index_off; > + } > + } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) { > + app_metadata[0] |= 2; /* Tx Full Checksum Offload Enabled */ > + } > + > + dma_tx_desc = lp->tx_chan->device->device_prep_slave_sg(lp->tx_chan, skbuf_dma->sgl, Possibly store the device_prep_slave_sg pointer to a temporary variable to make this line less painfully long? > + skbuf_dma = axienet_get_rx_desc(lp, lp->rx_ring_head); > + if (!skbuf_dma) > + return -ENOMEM; > + lp->rx_ring_head++; > + skb = netdev_alloc_skb(ndev, lp->max_frm_size); > + if (!skb) > + return -ENOMEM; > + > + sg_init_table(skbuf_dma->sgl, 1); > + addr = dma_map_single(lp->dev, skb->data, lp->max_frm_size, DMA_FROM_DEVICE); > + if (unlikely(dma_mapping_error(lp->dev, addr))) { > + netdev_err(ndev, "DMA mapping error\n"); needs rate limiting > + ret = -ENOMEM; > + goto rx_submit_err_free_skb; is it legal to unmap dma error ? > + } > + sg_dma_address(skbuf_dma->sgl) = addr; > + sg_dma_len(skbuf_dma->sgl) = lp->max_frm_size; > + dma_rx_desc = dmaengine_prep_slave_sg(lp->rx_chan, skbuf_dma->sgl, > + 1, DMA_DEV_TO_MEM, > + DMA_PREP_INTERRUPT); > +/** > + * axienet_init_dmaengine - init the dmaengine code. > + * @ndev: Pointer to net_device structure > + * > + * Return: 0, on success. > + * non-zero error value on failure > + * > + * This is the dmaengine initialization code. > + */ > +static int axienet_init_dmaengine(struct net_device *ndev) > +{ > + struct axienet_local *lp = netdev_priv(ndev); > + struct skbuf_dma_descriptor *skbuf_dma; > + int i, ret; > + > + lp->tx_chan = dma_request_chan(lp->dev, "tx_chan0"); > + if (IS_ERR(lp->tx_chan)) { > + ret = PTR_ERR(lp->tx_chan); > + return dev_err_probe(lp->dev, ret, "No Ethernet DMA (TX) channel found\n"); Why use dev_err_probe()? This is not on the probe path. If ndo_open fails it fails, it won't get retried later by itself, right? > @@ -1238,7 +1540,24 @@ static int axienet_open(struct net_device *ndev) > > phylink_start(lp->phylink); > > - if (!lp->use_dmaengine) { > + if (lp->use_dmaengine) { > + /* Enable interrupts for Axi Ethernet core (if defined) */ > + if (lp->eth_irq > 0) { > + ret = request_irq(lp->eth_irq, axienet_eth_irq, IRQF_SHARED, > + ndev->name, ndev); > + if (ret) > + goto error_code; > + } > + > + ret = axienet_init_dmaengine(ndev); > + pointless new line > + if (ret < 0) { > + if (lp->eth_irq > 0) > + free_irq(lp->eth_irq, ndev); can't this be on the error path? > + goto error_code; > + } > + pointless new line > + } else { -- pw-bot: cr
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