Subject: Re: [PATCH net-next] net: bcmgenet: enable driver to work without a device tree

From: Florian Fainelli <[email-masked]>
Date: Mon, 01 Dec 2014 13:20:48 -0800

On 01/12/14 13:13, Petri Gynther wrote:
> Hi Florian,
> 
> Getting back to this (finally). I have made changes per your comments.
> Sending a new patch shortly.

Ok, I am still a little bit hesitant in accepting these changes
considering that Kevin spent some time making a BMIPS multiplatform
kernel to work on 7425, 7435 [1]. Let's see how your changes look like,
and we can decide by then.

https://lwn.net/Articles/622947/

> 
> -- Petri
> 
> On Fri, Oct 10, 2014 at 12:46 PM, Petri Gynther <[email-masked]> wrote:
>> Hi Florian,
>>
>> On Fri, Oct 10, 2014 at 11:59 AM, Florian Fainelli <[email-masked]> wrote:
>>> On 10/10/2014 11:35 AM, Petri Gynther wrote:
>>>> Broadcom 7xxx MIPS-based STB platforms do not use device trees.
>>>> Modify bcmgenet driver so that it can be used on those platforms.
>>>>
>>>> Signed-off-by: Petri Gynther <[email-masked]>
>>>> ---
>>>
>>> [snip]
>>>
>>>> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.h b/drivers/net/ethernet/broadcom/genet/bcmgenet.h
>>>> index dbf524e..5191e3f 100644
>>>> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.h
>>>> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.h
>>>> @@ -17,6 +17,17 @@
>>>>  #include <linux/if_vlan.h>
>>>>  #include <linux/phy.h>
>>>>
>>>> +struct bcmgenet_platform_data {
>>>> +     void __iomem    *base_reg;
>>>> +     int             irq0;
>>>> +     int             irq1;
>>>
>>> Why would these members here? The platform device should provide those
>>> as standard resources that the driver fetches using
>>> platform_get_resource() and platform_get_irq().
>>>
>>
>> I modeled this on struct bcmemac_platform_data that was used in the
>> legacy BRCMSTB code.
>> include/linux/brcmstb/brcmstb.h:
>>
>> struct bcmemac_platform_data {
>>         /* used by the BSP code only */
>>         uintptr_t               base_reg;
>>         int                     irq0;
>>         int                     irq1;
>>
>>         int                     phy_type;
>>         int                     phy_id;
>>         int                     phy_speed;
>>         u8                      macaddr[ETH_ALEN];
>> };
>>
>> The legacy BRCMSTB code stores all relevant GENET info in this struct
>> and then creates the resources from that info:
>>
>> static void __init brcm_register_genet(int id, struct bcmemac_platform_data *pd)
>> {
>>         struct resource res[3];
>>         struct platform_device *pdev;
>>
>>         memset(&res, 0, sizeof(res));
>>         res[0].start = BPHYSADDR(pd->base_reg);
>>         res[0].end = BPHYSADDR(pd->base_reg + 0x4fff);
>>         res[0].flags = IORESOURCE_MEM;
>>
>>         res[1].start = res[1].end = pd->irq0;
>>         res[1].flags = IORESOURCE_IRQ;
>>
>>         res[2].start = res[2].end = pd->irq1;
>>         res[2].flags = IORESOURCE_IRQ;
>>
>>         brcm_alloc_macaddr(pd->macaddr);
>>
>>         pdev = platform_device_alloc("bcmgenet", id);
>>         platform_device_add_resources(pdev, res, 3);
>>         platform_device_add_data(pdev, pd, sizeof(*pd));
>>         platform_device_add(pdev);
>> }
>>
>>>> +     int             phy_type;
>>>> +     int             phy_addr;
>>>> +     int             phy_speed;
>>>> +     u8              macaddr[ETH_ALEN];
>>>> +     int             genet_version;
>>>> +};
>>>
>>> I would rather we put this in include/linux/platform_data/bcmgenet.h
>>> where it belongs.
>>>
>>
>> I wasn't aware of the directory include/linux/platform_data/. Yes,
>> that's where this belongs.
>>
>>>> +
>>>>  /* total number of Buffer Descriptors, same for Rx/Tx */
>>>>  #define TOTAL_DESC                           256
>>>>
>>>> diff --git a/drivers/net/ethernet/broadcom/genet/bcmmii.c b/drivers/net/ethernet/broadcom/genet/bcmmii.c
>>>> index 9ff799a..e5ff913 100644
>>>> --- a/drivers/net/ethernet/broadcom/genet/bcmmii.c
>>>> +++ b/drivers/net/ethernet/broadcom/genet/bcmmii.c
>>>> @@ -157,6 +157,21 @@ static void bcmgenet_mii_setup(struct net_device *dev)
>>>>       phy_print_status(phydev);
>>>>  }
>>>>
>>>> +static int bcmgenet_moca_fphy_update(struct net_device *dev,
>>>> +                                  struct fixed_phy_status *status)
>>>> +{
>>>> +     struct bcmgenet_priv *priv = netdev_priv(dev);
>>>> +     struct phy_device *phydev = priv->phydev;
>>>> +
>>>> +     /*
>>>> +      * MoCA daemon updates phydev->autoneg to reflect the link status.
>>>> +      * Update MoCA fixed PHY status accordingly, so that the PHY state
>>>> +      * machine becomes aware of the real link status.
>>>> +      */
>>>> +     status->link = phydev->autoneg;
>>>> +     return 0;
>>>> +}
>>>
>>> I don't want to see that in the upstream driver, please enable the link
>>> interrupts like I suggested before and do not use the autoneg field at
>>> all, which should require no MoCA daemon modifications.
>>>
>>
>> I added debug printk's to bcmgenet_isr0 to check on UMAC_IRQ_LINK_UP
>> and UMAC_IRQ_LINK_DOWN.
>> I am not getting those interrupts on eth1 (MoCA) port when coax is
>> removed/inserted.
>> But, they do work on eth0.
>>
>> I'll modify init_umac() to enable those interrupts for MoCA port and retest.
>>
>>> [snip]
>>>
>>>>
>>>>       priv->phydev = phydev;
>>>> @@ -437,6 +464,104 @@ static int bcmgenet_mii_of_init(struct bcmgenet_priv *priv)
>>>>       return 0;
>>>>  }
>>>>
>>>> +static int bcmgenet_mii_pd_init(struct bcmgenet_priv *priv)
>>>> +{
>>>> +     struct device *kdev = &priv->pdev->dev;
>>>> +     struct bcmgenet_platform_data *pd = kdev->platform_data;
>>>> +     struct mii_bus *mdio = priv->mii_bus;
>>>> +     int phy_addr = pd->phy_addr;
>>>> +     struct phy_device *phydev;
>>>> +     int ret;
>>>> +     int i;
>>>> +
>>>> +     /* Disable automatic MDIO bus scan */
>>>> +     mdio->phy_mask = ~0;
>>>> +
>>>> +     /* Clear all the IRQ properties */
>>>> +     if (mdio->irq)
>>>> +             for (i = 0; i < PHY_MAX_ADDR; i++)
>>>> +                     mdio->irq[i] = PHY_POLL;
>>>> +
>>>> +     /* Register the MDIO bus */
>>>> +     ret = mdiobus_register(mdio);
>>>> +     if (ret) {
>>>> +             dev_err(kdev, "failed to register MDIO bus\n");
>>>> +             return ret;
>>>> +     }
>>>> +
>>>> +     /*
>>>> +      * bcmgenet_platform_data needs to pass a valid PHY address for
>>>> +      * internal/external PHY or -1 for MoCA PHY.
>>>> +      */
>>>> +     if (phy_addr >= 0 && phy_addr < PHY_MAX_ADDR) {
>>>
>>> We do too much low-level PHY device handling, and since you already have
>>> the phy_type provided via platform_data, we can use that hint to do the
>>> following:
>>>
>>> 1) an internal or external PHY with MDIO accesses should leave the bus
>>> auto-probing on with the specified PHY address in the mdio bus phy_mask
>>>
>>> 2) a MoCA PHY or an external PHY with MDIO accesses disabled should use
>>> the fixed-0 MII bus instead.
>>>
>>> This would look like this:
>>>
>>> if (pd->phy_type != PHY_INTERFACE_MODE_MOCA || pd->mdio_enabled)
>>>         mdio->phy_mask = ~(1 << pd->phy_addr);
>>>
>>>         ...
>>>         mdiobus_register()
>>>
>>>         priv->phydev = mdio->bus->phy_map[pd->phy_addr];
>>>
>>>         phydev->phy_flags |= mask;
>>>
>>> if (pd->phy_type == PHY_INTERFACE_MODE_MOCA || !pd->mdio_enabled)
>>>         priv->phydev = fixed_phy_register(...);
>>>
>>> and in both cases, later on you do connect to the PHY device
>>>
>>> I can cook a patch to illustrate what I think this could look like since
>>> I realize using pseudo-code to explain might not be the best thing.
>>>
>>
>> I think I understand what you mean. I'll make a change.
>>
>>>> +             /*
>>>> +              * 10/100/1000 Ethernet port with external or internal PHY.
>>>> +              */
>>>> +             phydev = get_phy_device(mdio, phy_addr, false);
>>>> +             if (!phydev || IS_ERR(phydev)) {
>>>> +                     dev_err(kdev, "failed to create PHY device\n");
>>>> +                     mdiobus_unregister(mdio);
>>>> +                     return 1;
>>>> +             }
>>>> +
>>>> +             phydev->irq = PHY_POLL;
>>>> +
>>>> +             ret = phy_device_register(phydev);
>>>> +             if (ret) {
>>>> +                     dev_err(kdev, "failed to register PHY device\n");
>>>> +                     phy_device_free(phydev);
>>>> +                     mdiobus_unregister(mdio);
>>>> +                     return 1;
>>>> +             }
>>>> +
>>>> +             priv->phydev = phydev;
>>>> +             priv->phy_interface = pd->phy_type;
>>>> +     } else {
>>>> +             /*
>>>> +              * MoCA port with no MDIO-accessible PHY.
>>>> +              * We need to use 1000/HD fixed PHY to represent the link layer.
>>>> +              * MoCA daemon interacts with this PHY via ethtool.
>>>> +              */
>>>> +             struct fixed_phy_status moca_fphy_status = {
>>>> +                     .link = 0,
>>>> +                     .duplex = 0,
>>>
>>> This should be DUPLEX_FULL here, the link between GENET and the MoCA
>>> Ethernet convergence layer is full-duplex by nature (despite we report
>>> the PHY being half-duplex, which is a mistake in the downstream driver),
>>> the MoCA medium on the coaxial cable is half-duplex though, but that is
>>> handled by the MoCA HW.
>>>
>>> NB: I had issues in the past using a half-duplex link with the MoCA
>>> ethernet convergence layer, causing various types of packet loss because
>>> we use a simplified signaling internally in the hardware.
>>>
>>
>> I picked this setting from 3.3 GENET driver. I'll test 1000/FULL on my
>> platform to see if it works.
>>
>>>> +                     .speed = 1000,
>>>> +                     .pause = 0,
>>>> +                     .asym_pause = 0,
>>>> +             };
>>>> +
>>>> +             phydev = fixed_phy_register(PHY_POLL, &moca_fphy_status, NULL);
>>>> +             if (!phydev || IS_ERR(phydev)) {
>>>> +                     dev_err(kdev, "failed to register fixed PHY device\n");
>>>> +                     mdiobus_unregister(mdio);
>>>> +                     return 1;
>>>> +             }
>>>> +
>>>> +             phydev->autoneg = AUTONEG_DISABLE;
>>>> +
>>>> +             ret = fixed_phy_set_link_update(phydev,
>>>> +                                             bcmgenet_moca_fphy_update);
>>>> +             if (ret) {
>>>> +                     dev_err(kdev, "failed to set fixed PHY link update\n");
>>>> +             }
>>>
>>> Should not we propagate this error to the caller?
>>
>> Good catch. Yes.
>>
>>> --
>>> Florian