[PATCH 2/2] mvneta: use inband status only when link type is "auto"

The commit 898b2970e2c9 ("mvneta: implement SGMII-based in-band link state
signaling") implemented the link parameters auto-negotiation unconditionally.
Unfortunately it appears that some HW that implements SGMII protocol,
doesn't generate the inband status, so it is not possible to auto-negotiate
anything with such HW.

This patch enables the auto-negotiation only if the 'link' DT property
is set to "auto".
For old configurations where the 'link' property is not specified, the
default is to not use auto-negotiation.

This patch fixes the following regression:
https://lkml.org/lkml/2015/7/8/865
and is therefore CCed to stable.

Signed-off-by: Stas Sergeev <redacted>

CC: Thomas Petazzoni <redacted>
CC: netdev@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: stable@vger.kernel.org
---
 drivers/net/ethernet/marvell/mvneta.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 74176ec..b7f4d7f 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c

@@ -3009,7 +3009,7 @@ static int mvneta_probe(struct platform_device *pdev)
 	char hw_mac_addr[ETH_ALEN];
 	const char *mac_from;
 	int phy_mode;
-	int fixed_phy = 0;
+	int autoneg_link = 0;
 	int err;

 	/* Our multiqueue support is not complete, so for now, only

@@ -3043,7 +3043,7 @@ static int mvneta_probe(struct platform_device *pdev)
 			dev_err(&pdev->dev, "cannot register fixed PHY\n");
 			goto err_free_irq;
 		}
-		fixed_phy = 1;
+		autoneg_link = of_phy_is_autoneg_link(dn);

 		/* In the case of a fixed PHY, the DT node associated
 		 * to the PHY is the Ethernet MAC DT node.

@@ -3068,7 +3068,7 @@ static int mvneta_probe(struct platform_device *pdev)
 	pp->phy_node = phy_node;
 	pp->phy_interface = phy_mode;
 	pp->use_inband_status = (phy_mode == PHY_INTERFACE_MODE_SGMII) &&
-				fixed_phy;
+				autoneg_link;

 	pp->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(pp->clk)) {

-- 
1.9.1

On 09/07/15 10:41, Stas Sergeev wrote:

The commit 898b2970e2c9 ("mvneta: implement SGMII-based in-band link state
signaling") implemented the link parameters auto-negotiation unconditionally.
Unfortunately it appears that some HW that implements SGMII protocol,
doesn't generate the inband status, so it is not possible to auto-negotiate
anything with such HW.

What is the purpose of using the in-band status in the first place if
you end-up having to specify a 'fixed-link' property which contains most
of the link parameters: speed, duplex etc...?

-- 
Florian

09.07.2015 21:18, Florian Fainelli пишет:

On 09/07/15 10:41, Stas Sergeev wrote:

quoted

The commit 898b2970e2c9 ("mvneta: implement SGMII-based in-band link state
signaling") implemented the link parameters auto-negotiation unconditionally.
Unfortunately it appears that some HW that implements SGMII protocol,
doesn't generate the inband status, so it is not possible to auto-negotiate
anything with such HW.

What is the purpose of using the in-band status in the first place if
you end-up having to specify a 'fixed-link' property which contains most
of the link parameters: speed, duplex etc...?

You don't have to.
My config from today is as simple as:

fixed-link {
  link = "auto";
};

and that's all.
Without my today's patch, only 'speed' is a mandatory - not too much.

On 09/07/15 13:26, Stas Sergeev wrote:

09.07.2015 21:18, Florian Fainelli пишет:

quoted

On 09/07/15 10:41, Stas Sergeev wrote:

quoted

The commit 898b2970e2c9 ("mvneta: implement SGMII-based in-band link
state
signaling") implemented the link parameters auto-negotiation
unconditionally.
Unfortunately it appears that some HW that implements SGMII protocol,
doesn't generate the inband status, so it is not possible to
auto-negotiate
anything with such HW.

What is the purpose of using the in-band status in the first place if
you end-up having to specify a 'fixed-link' property which contains most
of the link parameters: speed, duplex etc...?

You don't have to.
My config from today is as simple as:

fixed-link {
  link = "auto";
};

and that's all.
Without my today's patch, only 'speed' is a mandatory - not too much.

That makes me think that 'fixed-link' is not exactly what you want then,
you would probably want something like "marvell,use-in-band-status" or
something like this. It could be a more generic property that is not
Marvell specific after all, that would be fine.
-- 
Florian

10.07.2015 00:14, Florian Fainelli пишет:

On 09/07/15 13:26, Stas Sergeev wrote:

quoted

09.07.2015 21:18, Florian Fainelli пишет:

quoted

On 09/07/15 10:41, Stas Sergeev wrote:

quoted

The commit 898b2970e2c9 ("mvneta: implement SGMII-based in-band link
state
signaling") implemented the link parameters auto-negotiation
unconditionally.
Unfortunately it appears that some HW that implements SGMII protocol,
doesn't generate the inband status, so it is not possible to
auto-negotiate
anything with such HW.

What is the purpose of using the in-band status in the first place if
you end-up having to specify a 'fixed-link' property which contains most
of the link parameters: speed, duplex etc...?

You don't have to.
My config from today is as simple as:

fixed-link {
   link = "auto";
};

and that's all.
Without my today's patch, only 'speed' is a mandatory - not too much.

That makes me think that 'fixed-link' is not exactly what you want then,
you would probably want something like "marvell,use-in-band-status" or
something like this. It could be a more generic property that is not
Marvell specific after all, that would be fine.

I think there is some confusion around fixed-link, because
of its name. This is what fixed-link is:
---
Some Ethernet MACs have a "fixed link", and are not connected to a
normal MDIO-managed PHY device.
---
A bit vague, but to me it means "non-MDIO", and that's all.
If we make it like "marvell,use-in-band-status", then it will
suddenly cancel everything in a fixed-link definition, which
is non obvious. Or, if we make it so that fixed-link def is
not needed in presence of "marvell,use-in-band-status", then
this "marvell,use-in-band-status" will have to silently enable
the fixed-phy driver the way fixed-link does.
If we just view fixed-link as non-MDIO link, then everything
fits, IMHO.