Re: [RFC PATCH 5/6] net: marvell: neta: add support for 2500base-X

[Kishon Vijay Abraham I <kishon@ti.com>]

Hi,

On 14/11/18 4:41 PM, Russell King - ARM Linux wrote:
> On Wed, Nov 14, 2018 at 02:18:14PM +0530, Kishon Vijay Abraham I wrote:
>> Hi,
>>
>> On 12/11/18 6:01 PM, Russell King wrote:
>>> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
>>> ---
>>>  drivers/net/ethernet/marvell/mvneta.c | 58 ++++++++++++++++++++++++++++++-----
>>>  1 file changed, 51 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
>>> index 5bfd349bf41a..7305d4cc0630 100644
>>> --- a/drivers/net/ethernet/marvell/mvneta.c
>>> +++ b/drivers/net/ethernet/marvell/mvneta.c
>>> @@ -27,6 +27,7 @@
>>>  #include <linux/of_irq.h>
>>>  #include <linux/of_mdio.h>
>>>  #include <linux/of_net.h>
>>> +#include <linux/phy/phy.h>
>>>  #include <linux/phy.h>
>>>  #include <linux/phylink.h>
>>>  #include <linux/platform_device.h>
>>> @@ -437,6 +438,7 @@ struct mvneta_port {
>>>  	struct device_node *dn;
>>>  	unsigned int tx_csum_limit;
>>>  	struct phylink *phylink;
>>> +	struct phy *comphy;
>>>  
>>>  	struct mvneta_bm *bm_priv;
>>>  	struct mvneta_bm_pool *pool_long;
>>> @@ -3150,6 +3152,8 @@ static void mvneta_start_dev(struct mvneta_port *pp)
>>>  {
>>>  	int cpu;
>>>  
>>> +	WARN_ON(phy_power_on(pp->comphy));
>>> +
>>>  	mvneta_max_rx_size_set(pp, pp->pkt_size);
>>>  	mvneta_txq_max_tx_size_set(pp, pp->pkt_size);
>>>  
>>> @@ -3212,6 +3216,8 @@ static void mvneta_stop_dev(struct mvneta_port *pp)
>>>  
>>>  	mvneta_tx_reset(pp);
>>>  	mvneta_rx_reset(pp);
>>> +
>>> +	WARN_ON(phy_power_off(pp->comphy));
>>>  }
>>>  
>>>  static void mvneta_percpu_enable(void *arg)
>>> @@ -3337,6 +3343,7 @@ static int mvneta_set_mac_addr(struct net_device *dev, void *addr)
>>>  static void mvneta_validate(struct net_device *ndev, unsigned long *supported,
>>>  			    struct phylink_link_state *state)
>>>  {
>>> +	struct mvneta_port *pp = netdev_priv(ndev);
>>>  	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };
>>>  
>>>  	/* We only support QSGMII, SGMII, 802.3z and RGMII modes */
>>> @@ -3357,14 +3364,14 @@ static void mvneta_validate(struct net_device *ndev, unsigned long *supported,
>>>  	/* Asymmetric pause is unsupported */
>>>  	phylink_set(mask, Pause);
>>>  
>>> -	/* We cannot use 1Gbps when using the 2.5G interface. */
>>> -	if (state->interface == PHY_INTERFACE_MODE_2500BASEX) {
>>> -		phylink_set(mask, 2500baseT_Full);
>>> -		phylink_set(mask, 2500baseX_Full);
>>> -	} else {
>>> +	/* Half-duplex at speeds higher than 100Mbit is unsupported */
>>> +	if (pp->comphy || state->interface != PHY_INTERFACE_MODE_2500BASEX) {
>>>  		phylink_set(mask, 1000baseT_Full);
>>>  		phylink_set(mask, 1000baseX_Full);
>>>  	}
>>> +	if (pp->comphy || state->interface == PHY_INTERFACE_MODE_2500BASEX) {
>>> +		phylink_set(mask, 2500baseX_Full);
>>> +	}
>>>  
>>>  	if (!phy_interface_mode_is_8023z(state->interface)) {
>>>  		/* 10M and 100M are only supported in non-802.3z mode */
>>> @@ -3378,6 +3385,11 @@ static void mvneta_validate(struct net_device *ndev, unsigned long *supported,
>>>  		   __ETHTOOL_LINK_MODE_MASK_NBITS);
>>>  	bitmap_and(state->advertising, state->advertising, mask,
>>>  		   __ETHTOOL_LINK_MODE_MASK_NBITS);
>>> +
>>> +	/* We can only operate at 2500BaseX or 1000BaseX.  If requested
>>> +	 * to advertise both, only report advertising at 2500BaseX.
>>> +	 */
>>> +	phylink_helper_basex_speed(state);
>>>  }
>>>  
>>>  static int mvneta_mac_link_state(struct net_device *ndev,
>>> @@ -3389,7 +3401,9 @@ static int mvneta_mac_link_state(struct net_device *ndev,
>>>  	gmac_stat = mvreg_read(pp, MVNETA_GMAC_STATUS);
>>>  
>>>  	if (gmac_stat & MVNETA_GMAC_SPEED_1000)
>>> -		state->speed = SPEED_1000;
>>> +		state->speed =
>>> +			state->interface == PHY_INTERFACE_MODE_2500BASEX ?
>>> +			SPEED_2500 : SPEED_1000;
>>>  	else if (gmac_stat & MVNETA_GMAC_SPEED_100)
>>>  		state->speed = SPEED_100;
>>>  	else
>>> @@ -3504,12 +3518,32 @@ static void mvneta_mac_config(struct net_device *ndev, unsigned int mode,
>>>  			    MVNETA_GMAC_FORCE_LINK_DOWN);
>>>  	}
>>>  
>>> +
>>>  	/* When at 2.5G, the link partner can send frames with shortened
>>>  	 * preambles.
>>>  	 */
>>>  	if (state->speed == SPEED_2500)
>>>  		new_ctrl4 |= MVNETA_GMAC4_SHORT_PREAMBLE_ENABLE;
>>>  
>>> +	if (pp->comphy) {
>>> +		enum phy_mode mode = PHY_MODE_INVALID;
>>> +
>>> +		switch (state->interface) {
>>> +		case PHY_INTERFACE_MODE_SGMII:
>>> +		case PHY_INTERFACE_MODE_1000BASEX:
>>> +			mode = PHY_MODE_SGMII;
>>> +			break;
>>> +		case PHY_INTERFACE_MODE_2500BASEX:
>>> +			mode = PHY_MODE_2500SGMII;
>>> +			break;
>>> +		default:
>>> +			break;
>>> +		}
>>> +
>>> +		if (mode != PHY_MODE_INVALID)
>>> +			WARN_ON(phy_set_mode(pp->comphy, mode));
>>> +	}
>>> +
>>>  	if (new_ctrl0 != gmac_ctrl0)
>>>  		mvreg_write(pp, MVNETA_GMAC_CTRL_0, new_ctrl0);
>>>  	if (new_ctrl2 != gmac_ctrl2)
>>> @@ -4411,7 +4445,7 @@ static int mvneta_port_power_up(struct mvneta_port *pp, int phy_mode)
>>>  	if (phy_mode == PHY_INTERFACE_MODE_QSGMII)
>>>  		mvreg_write(pp, MVNETA_SERDES_CFG, MVNETA_QSGMII_SERDES_PROTO);
>>>  	else if (phy_mode == PHY_INTERFACE_MODE_SGMII ||
>>> -		 phy_mode == PHY_INTERFACE_MODE_1000BASEX)
>>> +		 phy_interface_mode_is_8023z(phy_mode))
>>>  		mvreg_write(pp, MVNETA_SERDES_CFG, MVNETA_SGMII_SERDES_PROTO);
>>>  	else if (!phy_interface_mode_is_rgmii(phy_mode))
>>>  		return -EINVAL;
>>> @@ -4428,6 +4462,7 @@ static int mvneta_probe(struct platform_device *pdev)
>>>  	struct mvneta_port *pp;
>>>  	struct net_device *dev;
>>>  	struct phylink *phylink;
>>> +	struct phy *comphy;
>>>  	const char *dt_mac_addr;
>>>  	char hw_mac_addr[ETH_ALEN];
>>>  	const char *mac_from;
>>> @@ -4453,6 +4488,14 @@ static int mvneta_probe(struct platform_device *pdev)
>>>  		goto err_free_irq;
>>>  	}
>>>  
>>> +	comphy = devm_of_phy_get(&pdev->dev, dn, NULL);
>>> +	if (comphy == ERR_PTR(-EPROBE_DEFER)) {
>>> +		err = -EPROBE_DEFER;
>>> +		goto err_free_irq;
>>> +	} else if (IS_ERR(comphy)) {
>>> +		comphy = NULL;
>>> +	}
>>
>> devm_phy_optional_get can be used here instead.
> 
> I don't think that will work with a NULL string.

That's correct.
> 
> devm_phy_optional_get() ultimately ends up calling phy_get(), which
> in this case would receive a NULL string.  It will pass that NULL
> string to of_property_match_string().

There is a check for (string == NULL), even before of_property_match_string is
invoked in phy_get()
> 
> of_property_match_string() will try to find the "phy-names" property,
> which will not exist, and hence will return -EINVAL.
> 
> phy_get() doesn't check for error conditions, but passes this directly
> to _of_phy_get() as the index.  _of_phy_get() passes that on to
> of_parse_phandle_with_args(), which will fail to find an entry with
> cur_index == -EINVAL (since it counts up from zero.)  Hence,
> _of_phy_get() will return -ENODEV, thereby causing
> devm_phy_optional_get() to return NULL, even if there's a phys=
> property present.
> 
> of_phy_get() and phy_get() have different behaviours when a NULL string
> is passed in - the of_phy_get() family will get the first PHY specified
> in the DT phys= property, whereas the phy_get() family of functions
> will fail.

Agreed. I'll fix this so that we have similar behavior with of_phy_get() and
phy_get().
> 
> Since there is no devm_of_phy_optional_get(), that leads people down
> the path of coding that functionality at the callsites, such as in
> drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c.

Okay.

Thanks
Kishon


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