2014-03-03 10:21 GMT-08:00 Vince Bridgers <vbridgers2013@xxxxxxxxx>: > Hello Florian, thank you for taking the time to comments. My responses inline. > > On Sun, Mar 2, 2014 at 6:59 PM, Florian Fainelli <f.fainelli@xxxxxxxxx> wrote: >> Hello Vince, >> >> It might help reviewing the patches by breaking the patches into: >> >> - the SGDMA bits >> - the MSGDMA bits >> - the Ethernet MAC driver per-se > > I'll break down the next submission. > >> >> BTW, it does look like the SGDMA code could/should be a dmaengine driver? > > I did consider this, but after studying the dmaengine api I found the > API definitions and semantics were not a match to the way the SGDMA > and MSGDMA behave collectively. Moreover, I could not find an example > of an Ethernet driver that made use of the dmaengine API - only the > Micrel driver seems to use it. When studying what components actually > used the dmaengine API I concluded the dmaengine API was defined for > use cases different than Ethernet. To tell you the truth, I have myself been toying with the idea of using a dmaengine driver for some Ethernet drivers out there (mainly bcm63xx_enet), but so far have not had any chance to take a stab at doing a real implementation. My concern was more about the fact that maybe the SGDMA/MSGDMA code could be reusable for other peripherals in your system, such as USB device, PCM etc... This is fine anyway. [snip] >> >> Is this the software number of descriptors or hardware number of >> descriptors? > > This number applies to the number of descriptors as limited by the > MSGDMA capabilities. The SGDMA has different limitations and issues, > but the maximum number of descriptors for either DMA engine that can > be used is represented as shown above. This is important since an > unusual hardware configuration could support both SGDMA and MSGDMA > simultaneously for more than one TSE instance. I used a design that > supported a single SGDMA with TSE and a single MSGDMA with TSE for > testing purposes (among other designs). So this a hardware defined > number of descriptors and is fixed. Ok, so this describes a hardware configuration, and as such should be part of some Device Tree properties, something that could easily be changed by someone wanting to slightly modify the RTL parameters. > >> >> [snip] >> >> >>> + >>> +static int altera_tse_mdio_create(struct net_device *dev, unsigned int >>> id) >>> +{ >>> + struct altera_tse_private *priv = netdev_priv(dev); >>> + int ret; >>> + int i; >>> + struct device_node *mdio_node; >>> + struct mii_bus *mdio; >>> + >>> + mdio_node = of_find_compatible_node(priv->device->of_node, NULL, >>> + "altr,tse-mdio"); >>> + >>> + if (mdio_node) { >>> + dev_warn(priv->device, "FOUND MDIO subnode\n"); >>> + } else { >>> + dev_warn(priv->device, "NO MDIO subnode\n"); >>> + return 0; >>> + } >>> + >>> + mdio = mdiobus_alloc(); >>> + if (mdio == NULL) { >>> + dev_err(priv->device, "Error allocating MDIO bus\n"); >>> + return -ENOMEM; >>> + } >>> + >>> + mdio->name = ALTERA_TSE_RESOURCE_NAME; >>> + mdio->read = &altera_tse_mdio_read; >>> + mdio->write = &altera_tse_mdio_write; >>> + snprintf(mdio->id, MII_BUS_ID_SIZE, "%s-%u", mdio->name, id); >> >> >> You could use something more user-friendly such as mdio_node->full_name. > > The full name will exceed the characters available in that particular > structure data member. MII_BUS_ID_SIZE is defined as (20-3) in > include/linux/phy.h. The full name would exceed the allocated space in > that structure. That's why this method was chosen. Ok, that works too. > >> >> >>> + >>> + mdio->irq = kcalloc(PHY_MAX_ADDR, sizeof(int), GFP_KERNEL); >>> + if (mdio->irq == NULL) { >>> + dev_err(priv->device, "%s: Cannot allocate memory\n", >>> __func__); >>> + ret = -ENOMEM; >>> + goto out_free_mdio; >>> + } >>> + for (i = 0; i < PHY_MAX_ADDR; i++) >>> + mdio->irq[i] = PHY_POLL; >>> + >>> + mdio->priv = (void *)priv->mac_dev; >> >> >> No need for the cast here, this is already a void *. > > Noted. > >> >> >>> + mdio->parent = priv->device; >> >> >> [snip] >> >> >>> + /* make cache consistent with receive packet buffer */ >>> + dma_sync_single_for_cpu(priv->device, >>> + priv->rx_ring[entry].dma_addr, >>> + priv->rx_ring[entry].len, >>> + DMA_FROM_DEVICE); >>> + >>> + dma_unmap_single(priv->device, >>> priv->rx_ring[entry].dma_addr, >>> + priv->rx_ring[entry].len, >>> DMA_FROM_DEVICE); >>> + >>> + /* make sure all pending memory updates are complete */ >>> + rmb(); >> >> >> Are you sure this does something in your case? I am fairly sure that the >> dma_unmap_single() call would have done that implicitely for you here. > > I wrote the code this way intentionally to be explicit. I'll check the > API for behavior as you describe for both ARM and NIOS and if not > handled this barrier should probably remain. > [snip] >> >> I am not sure this will even be triggered if you want do not advertise >> NETIF_F_SG, so you might want to drop that entirely. > > The intent was to add Scatter Gather capabilities at some point in the > future, so this was a form of documenting. I'll just drop the code and > add a comment instead if you agree. Since you are not advertising the NETIF_F_SG capability bit, you should probably just drop this code and add it back again under a different form when SG support is added. [snip] >> >> You might rather do this during your driver probe function rather than in >> the ndo_open() callback. > > This seems to be the normal place to probe and initialize the phy from > examination of existing code. Perhaps I missed something, could you > provide an example of where this is done differently? Most drivers I can think about: tg3, bcmgenet, bcm63xx_enet, r6040 do probe for the PHY in their driver's probe routine. > >> >> [snip] >> >> >>> + /* Stop and disconnect the PHY */ >>> + if (priv->phydev) { >>> + phy_stop(priv->phydev); >>> + phy_disconnect(priv->phydev); >>> + priv->phydev = NULL; >>> + } >>> + >>> + netif_stop_queue(dev); >>> + napi_disable(&priv->napi); >>> + >>> + /* Disable DMA interrupts */ >>> + spin_lock_irqsave(&priv->rxdma_irq_lock, flags); >>> + priv->disable_rxirq(priv); >>> + priv->disable_txirq(priv); >>> + spin_unlock_irqrestore(&priv->rxdma_irq_lock, flags); >>> + >>> + /* Free the IRQ lines */ >>> + free_irq(priv->rx_irq, dev); >>> + free_irq(priv->tx_irq, dev); >>> + >>> + /* disable and reset the MAC, empties fifo */ >>> + spin_lock(&priv->mac_cfg_lock); >>> + spin_lock(&priv->tx_lock); >>> + >>> + ret = reset_mac(priv); >>> + if (ret) >>> + netdev_err(dev, "Cannot reset MAC core (error: %d)\n", >>> ret); >>> + priv->reset_dma(priv); >>> + free_skbufs(dev); >>> + >>> + spin_unlock(&priv->tx_lock); >>> + spin_unlock(&priv->mac_cfg_lock); >>> + >>> + priv->uninit_dma(priv); >>> + >>> + netif_carrier_off(dev); >> >> >> phy_stop() does that already. > > If you mean phy_stop calls netif_carrier_off, I don't see it in that > function (phy/phy.c). Common usage in the intree drivers seems to be > calling netif_carrier_off in this context, but perhaps the drivers I > examined have not been updated. Is there some more specific feedback > or comments that you could provide here? Do you mean that > netif_carrier_off is unnecessary here? by calling phy_stop() the PHY state machine will move to the state PHY_HALTED, if the link state was valid at this point, it will call netif_carrier_off(). If the link was not valid before, the PHY state machine would have already called netif_carrier_off(). > >> >> >>> + >>> + return 0; >>> +} >>> + >>> +static struct net_device_ops altera_tse_netdev_ops = { >>> + .ndo_open = tse_open, >>> + .ndo_stop = tse_shutdown, >>> + .ndo_start_xmit = tse_start_xmit, >>> + .ndo_set_mac_address = eth_mac_addr, >>> + .ndo_set_rx_mode = tse_set_rx_mode, >>> + .ndo_change_mtu = tse_change_mtu, >>> + .ndo_validate_addr = eth_validate_addr, >>> +}; >>> + >>> +static int altera_tse_get_of_prop(struct platform_device *pdev, >>> + const char *name, unsigned int *val) >>> +{ >>> + const __be32 *tmp; >>> + int len; >>> + char buf[strlen(name)+1]; >>> + >>> + tmp = of_get_property(pdev->dev.of_node, name, &len); >>> + if (!tmp && !strncmp(name, "altr,", 5)) { >>> + strcpy(buf, name); >>> + strncpy(buf, "ALTR,", 5); >>> + tmp = of_get_property(pdev->dev.of_node, buf, &len); >>> + } >>> + if (!tmp || (len < sizeof(__be32))) >>> + return -ENODEV; >>> + >>> + *val = be32_to_cpup(tmp); >>> + return 0; >>> +} >> >> >> Do we really need that abstration? > > The intent here is to support legacy device trees that were created > with upper case "ALTR". Oh Device Tree fun, welcome to the club. > >> >> >>> + >>> +static int altera_tse_get_phy_iface_prop(struct platform_device *pdev, >>> + phy_interface_t *iface) >>> +{ >>> + const void *prop; >>> + int len; >>> + >>> + prop = of_get_property(pdev->dev.of_node, "phy-mode", &len); >>> + if (!prop) >>> + return -ENOENT; >>> + if (len < 4) >>> + return -EINVAL; >>> + >>> + if (!strncmp((char *)prop, "mii", 3)) { >>> + *iface = PHY_INTERFACE_MODE_MII; >>> + return 0; >>> + } else if (!strncmp((char *)prop, "gmii", 4)) { >>> + *iface = PHY_INTERFACE_MODE_GMII; >>> + return 0; >>> + } else if (!strncmp((char *)prop, "rgmii-id", 8)) { >>> + *iface = PHY_INTERFACE_MODE_RGMII_ID; >>> + return 0; >>> + } else if (!strncmp((char *)prop, "rgmii", 5)) { >>> + *iface = PHY_INTERFACE_MODE_RGMII; >>> + return 0; >>> + } else if (!strncmp((char *)prop, "sgmii", 5)) { >>> + *iface = PHY_INTERFACE_MODE_SGMII; >>> + return 0; >>> + } >> >> >> of_get_phy_mode() does that for you. > > Will address this. Thank you. > >> >> >>> + >>> + return -EINVAL; >>> +} >>> + >>> +static int request_and_map(struct platform_device *pdev, const char >>> *name, >>> + struct resource **res, void __iomem **ptr) >>> +{ >>> + struct resource *region; >>> + struct device *device = &pdev->dev; >>> + >>> + *res = platform_get_resource_byname(pdev, IORESOURCE_MEM, name); >>> + if (*res == NULL) { >>> + dev_err(device, "resource %s not defined\n", name); >>> + return -ENODEV; >>> + } >>> + >>> + region = devm_request_mem_region(device, (*res)->start, >>> + resource_size(*res), >>> dev_name(device)); >>> + if (region == NULL) { >>> + dev_err(device, "unable to request %s\n", name); >>> + return -EBUSY; >>> + } >>> + >>> + *ptr = devm_ioremap_nocache(device, region->start, >>> + resource_size(region)); >>> + if (*ptr == NULL) { >>> + dev_err(device, "ioremap_nocache of %s failed!", name); >>> + return -ENOMEM; >>> + } >>> + >>> + return 0; >>> +} >>> + >>> +/* Probe Altera TSE MAC device >>> + */ >>> +static int altera_tse_probe(struct platform_device *pdev) >>> +{ >>> + struct net_device *ndev; >>> + int ret = -ENODEV; >>> + struct resource *control_port; >>> + struct resource *dma_res; >>> + struct altera_tse_private *priv; >>> + int len; >>> + const unsigned char *macaddr; >>> + struct device_node *np = pdev->dev.of_node; >>> + unsigned int descmap; >>> + >>> + ndev = alloc_etherdev(sizeof(struct altera_tse_private)); >>> + if (!ndev) { >>> + dev_err(&pdev->dev, "Could not allocate network >>> device\n"); >>> + return -ENODEV; >>> + } >>> + >>> + SET_NETDEV_DEV(ndev, &pdev->dev); >>> + >>> + priv = netdev_priv(ndev); >>> + priv->device = &pdev->dev; >>> + priv->dev = ndev; >>> + priv->msg_enable = netif_msg_init(debug, default_msg_level); >>> + >>> + if (of_device_is_compatible(np, "altr,tse-1.0") || >>> + of_device_is_compatible(np, "ALTR,tse-1.0")) { >> >> >> Use the .data pointer associated with the compatible string to help you do >> that, see below. > > Noted. If we can agree that use of the dmaengine api is inappropriate > in this case, I'll update the code to use a .data pointer as > suggested. Thank you for the comment. I think not using the dmaengine API is fine. > >> >> [snip] >> >> >>> + /* get supplemental address settings for this instance */ >>> + ret = altera_tse_get_of_prop(pdev, "altr,enable-sup-addr", >>> + &priv->added_unicast); >>> + if (ret) >>> + priv->added_unicast = 0; >>> + >>> + /* Max MTU is 1500, ETH_DATA_LEN */ >>> + priv->max_mtu = ETH_DATA_LEN; >> >> >> How about VLANs? If this is always 1500, just let the core ethernet >> functions configure the MTU for your interface. > > The TSE core handles frame size expansion for VLAN tagged frames, so > it's ok (tested). At some point, frame sizes > 1518 may be supported > (the core supports Jumbo frames, the driver is intentionally simple > for initial submission). Your comment is noted, I accept the > suggestion. In case this needs to be matched against a newer version of the RTL, or whatever HW configuration some RTL user is allowed to make, you could probaly use the 'max-frame-size' ePAPR-defined property for this? > >> >> >>> + >>> + /* The DMA buffer size already accounts for an alignment bias >>> + * to avoid unaligned access exceptions for the NIOS processor, >>> + */ >>> + priv->rx_dma_buf_sz = ALTERA_RXDMABUFFER_SIZE; >>> + >>> + /* get default MAC address from device tree */ >>> + macaddr = of_get_property(pdev->dev.of_node, "local-mac-address", >>> &len); >>> + if (macaddr && len == ETH_ALEN) >>> + memcpy(ndev->dev_addr, macaddr, ETH_ALEN); >>> + >>> + /* If we didn't get a valid address, generate a random one */ >>> + if (!is_valid_ether_addr(ndev->dev_addr)) >>> + eth_hw_addr_random(ndev); >>> + >>> + ret = altera_tse_get_phy_iface_prop(pdev, &priv->phy_iface); >>> + if (ret == -ENOENT) { >>> + /* backward compatability, assume RGMII */ >>> + dev_warn(&pdev->dev, >>> + "cannot obtain PHY interface mode, assuming >>> RGMII\n"); >>> + priv->phy_iface = PHY_INTERFACE_MODE_RGMII; >>> + } else if (ret) { >>> + dev_err(&pdev->dev, "unknown PHY interface mode\n"); >>> + goto out_free; >>> + } >>> + >>> + /* try to get PHY address from device tree, use PHY autodetection >>> if >>> + * no valid address is given >>> + */ >>> + ret = altera_tse_get_of_prop(pdev, "altr,phy-addr", >>> &priv->phy_addr); >>> + if (ret) >>> + priv->phy_addr = POLL_PHY; >> >> >> Please do not use such as custom property, either you use an Ethernet PHY >> device tree node as described in ePAPR; or you do not and use a fixed-link >> property instead. > > Agreed, the code tries phy handles as described in the ePAPR v1.1 > specification, then falls back to the method in question. The intent > is to support legacy device trees as well. Is there a preferred way to > handle legacy configurations that we may encounter in the wild? Well, ideally a new driver should have no legacy at all, but I understand that situation might not be the case, I believe it should be duly noted in the Device Tree binding documentation (have not reviewed that patch yet). Issuing a warning might be beneficial as well to spot "old" DT bindings and help troubleshooting setups? -- Florian -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html