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

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

[Stas Sergeev]

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 <stsp@users.sourceforge.net>

CC: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
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

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

[Florian Fainelli]

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...?

> 
> 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 <stsp@users.sourceforge.net>
> 
> CC: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> 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)) {
> 


-- 
Florian

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

[Stas Sergeev]

09.07.2015 21:18, Florian Fainelli пишет:
> 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...?
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.

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

[Florian Fainelli]

On 09/07/15 13:26, Stas Sergeev wrote:
> 09.07.2015 21:18, Florian Fainelli пишет:
>> 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...?
> 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

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

[Stas Sergeev]

10.07.2015 00:14, Florian Fainelli пишет:
> On 09/07/15 13:26, Stas Sergeev wrote:
>> 09.07.2015 21:18, Florian Fainelli пишет:
>>> 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...?
>> 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.